Invasive Breast Cancer: Understanding Your Pathology Report After Surgery

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Invasive breast cancer starts in the breast. The breast is made of small glands that produce milk and ducts that carry it to the nipple. Almost all breast cancers begin in the cells lining those glands and ducts.

Invasive means the cancer cells have broken out of the gland or duct where they started. They have grown into the supporting tissue around it, which is called the stroma. Once a cancer has done that, it can reach lymph nodes under the arm. Less often, it travels to other parts of the body. That is called metastasis.

This article explains the pathology report created after surgery to remove an invasive breast cancer. The operation may be called a lumpectomy, a partial mastectomy, or a total mastectomy. Surgeons often remove lymph nodes from under the arm at the same time.

Why your pathology report looks like a checklist

Most breast cancer pathology reports include a section that looks like a list of headings, each followed by a short answer. This is called a synoptic report. It follows a standard checklist published by the College of American Pathologists (CAP). Laboratories across North America, Europe, and much of the world use the same one. The checklist makes sure that every feature known to affect treatment is reported for every patient, in the same words, no matter which laboratory examined the tissue.

One checklist covers every type of invasive breast carcinoma. The most common by far is invasive carcinoma of no special type, which most reports still call ductal carcinoma. The second is invasive lobular carcinoma. The rest are the special types, such as mucinous carcinoma and metaplastic carcinoma, and each is uncommon on its own.

The same checklist is used whether or not ductal carcinoma in situ, usually shortened to DCIS, is present alongside the invasive cancer. DCIS on its own is a different situation. It is reported on a separate checklist, because there is no invasive cancer to describe.

Because one checklist covers all of these tumors, your report may list items that do not apply to your situation. An item asking about the nipple will not apply if the operation removed only part of the breast. An item asking about treatment given before surgery applies only to patients who had it.

When an item does not apply, the report will say something like “not identified,” “not applicable,” or “cannot be determined.” Seeing those phrases does not mean something was missed. It usually means the feature was looked for and was not there, or that the tissue removed did not include the structure being asked about.

This checklist is used for cancer removed by an operation. A core needle biopsy or a skin biopsy is reported differently, and our guide to your breast biopsy pathology report covers that document. Re-excision of a margin after the main operation is also reported differently. Paget disease without an invasive cancer, phyllodes tumors, lymphoma, and sarcoma each have their own checklist. Biomarker results are reported on their own separate checklist, described near the end of this article.

This article covers every item on the checklist, in the order you will find them on your report. Reading it will help you understand what each term means and why it matters for your care.

How is the diagnosis made?

A pathologist diagnoses invasive breast cancer by examining a tissue sample under a microscope. In most cases a mammogram, an ultrasound, or an MRI first shows an abnormal area. A radiologist then samples it with a core needle biopsy, using imaging to guide the needle. A small metal clip is usually left behind to mark the spot. The report described in this article comes from the tissue removed later at surgery.

Under the microscope, the pathologist looks for cancer cells that have grown outside the normal glands and ducts. Normal glands and ducts are wrapped in a layer of myoepithelial cells. When that layer is gone and tumor cells sit directly in the surrounding tissue, the cancer has invaded. The pathologist then decides which type of breast cancer it is, based on how the cells are arranged and how they look.

When the appearance alone is not enough, the pathologist performs immunohistochemistry, a test that uses colored stains to show specific proteins in tissue. Stains for p63, calponin, and smooth muscle myosin show the myoepithelial layer, which helps confirm that invasion is present. A stain for E-cadherin helps separate lobular carcinoma from carcinoma of no special type, because lobular carcinoma cells usually lose that protein. If the pathologist suspects that the cancer in the breast may have started somewhere else, a broader panel of stains is used to find its origin.

After the diagnosis is confirmed, imaging assesses how far the disease has spread. The pathology report describes what was found in the removed tissue; imaging describes the rest of the body.

The operation and which breast the tissue came from

The first items on a breast cancer pathology report describe the specimen, meaning the tissue sent to the laboratory. They also state which breast it came from. Surgeons remove as little breast tissue as the cancer allows while still clearing it completely.

Excision — Removal of the cancer with a rim of surrounding breast tissue, leaving the rest of the breast in place. Your report or your surgeon may call this a lumpectomy, a partial mastectomy, a segmental resection, or a quadrantectomy. The nipple is usually not included.
Total mastectomy — Removal of all the breast tissue on that side. A skin-sparing mastectomy takes the nipple and only a narrow rim of skin. A nipple-sparing mastectomy leaves both the skin and the nipple in place.
Other — An operation that does not match those categories. The report names what was removed. A radical mastectomy, which takes the chest muscles as well, is recorded here.
Not specified — The request form did not state which operation was performed.
Specimen laterality — Whether the tissue came from the right breast or the left. Reports may say “not specified” when the request form did not state it.

Two other names appear in operating notes. A simple mastectomy is a total mastectomy with no lymph nodes removed. A modified radical mastectomy is a total mastectomy together with removal of the lymph nodes under the arm. In that operation the breast and the lymph nodes are usually described in separate parts of the report.

Tumor focality: one tumor or more than one

Focality describes how many separate areas of invasive breast cancer were found in the specimen. Two areas of invasion count as separate when they sit at least 5 millimeters apart. This item became a required part of the checklist in the current version, so it appears on every report.

Unifocal — One area of invasive cancer. This is the most common answer.
Multifocal, with similar features — More than one area, all of the same type and grade. These are usually satellites of one cancer, or the scattered remains of a cancer that responded to treatment.
Multifocal, with different features — More than one area, differing in type, grade, or biomarker results. These are treated as separate cancers that arose independently.
No residual invasive carcinoma — No invasive cancer was left in the specimen. This is seen after successful treatment given before surgery.
Cannot be determined — The number of separate areas could not be established, and the report explains why.
Number of foci — An optional count of how many areas were found, given as an exact number or as “at least” a number.

When the areas differ from one another, the pathologist may describe each one separately. Each gets a label such as “Lesion 1,” and its own site, type, grade, and size. That is why one report can contain several tumor descriptions.

Multiple areas do not add together. The tumor stage is based on the largest one alone. The letter “m” in brackets is added to show that more than one was present. Cancers in both breasts are always reported as two separate cases, never as one.

Tumor site: where in the breast the cancer was found

Tumor site records the location of the invasive cancer within the breast. It is an optional item, so some reports state it and others say “not specified.” The site is usually given as a clock position and a distance from the nipple, such as “3 o’clock, 2 cm from nipple.” It may instead name a quadrant of the breast, such as the upper outer quadrant.

This item exists so the cancer described here can be matched to the abnormality seen on imaging and to the earlier needle biopsy. Where treatment before surgery has removed the cancer entirely, the site refers to where it used to be.

Types of invasive breast cancer (histologic type)

Histologic type describes what the invasive breast cancer looks like under the microscope and how its cells are arranged. Pathologists assign the type using the World Health Organization (WHO) classification of breast tumors. Type matters because it affects how the cancer tends to behave, how it shows up on imaging, and how completely it can be removed.

Invasive carcinoma of no special type (ductal)

Invasive carcinoma of no special type is by far the most common form, accounting for roughly 70 to 80 out of every 100 invasive breast cancers. Older reports call it invasive ductal carcinoma, and many still do. The name is a description of what it is not. The tumor cells do not form the distinctive patterns that define the special types below, so the diagnosis is made once those have been excluded.

Under the microscope, the cells form sheets, nests, and irregular glands set in dense scar-like tissue. That firmness is why many of these cancers can be felt as a lump and are clearly visible on a mammogram. Behavior varies widely within this group, which is why the grade and the biomarker results matter so much here.

Some of these cancers have a distinctive appearance that is treated as a pattern rather than a separate type. Your report may name one of them. The patterns include neuroendocrine differentiation, a medullary pattern, and rarer ones such as osteoclast-like stromal giant cell rich. These are recorded alongside the diagnosis of no special type, not instead of it.

Invasive lobular carcinoma

Invasive lobular carcinoma is the second most common form, accounting for roughly 10 to 15 out of every 100 invasive breast cancers. Its cells are small and uniform, and they spread through the breast in single files rather than forming a solid lump. They have usually lost a protein called E-cadherin, which normally holds neighboring cells together.

That growth pattern has practical consequences the report may reflect. These cancers often cannot be felt and are harder to see on a mammogram, so the true size is frequently larger than imaging suggested. They are more often multifocal, and more often present in both breasts. Margins are more often positive at the first operation for the same reason.

The checklist separates two forms. Classic invasive lobular carcinoma has the small uniform cells described above. A variant pattern means the cells depart from that appearance, and the report names which variant, most often pleomorphic or histiocytoid. The pleomorphic variant tends to be higher grade.

Special types and other less common types

Each of the remaining types accounts for a small share of invasive breast cancers. Every one is named on the checklist so that a patient with an uncommon diagnosis can find it. For the favorable special types, the checklist requires that at least 90 percent of the tumor show that pattern before the name is used.

Tubular carcinoma — The tumor forms small, open, well-formed tubes. It is nearly always low grade and hormone receptor positive, and outcomes are excellent.
Invasive cribriform carcinoma — The tumor forms sieve-like sheets punched through with round spaces. It behaves much like tubular carcinoma.
Mucinous carcinoma — Small clusters of tumor cells float in large pools of mucin, a thick gel-like substance. It occurs more often in older patients and carries a favorable outlook.
Invasive micropapillary carcinoma — Small tufts of tumor cells sit in clear spaces with no supporting core. This form reaches lymph nodes more often than its size would suggest.
Invasive apocrine carcinoma — The cells are large, with abundant pink cytoplasm and prominent nucleoli. Most are hormone receptor negative but carry receptors for androgen instead.
Metaplastic carcinoma — The tumor cells have changed into another kind of tissue. The checklist names several forms, described in the paragraph below this list.
Invasive solid papillary carcinoma — Rounded nodules of tumor cells with delicate blood vessels running through them. It usually occurs in older patients and grows slowly.
Adenoid cystic carcinoma, classic — The same tumor that occurs in the salivary glands. In the breast it is usually triple negative yet still carries a favorable outlook.
Secretory carcinoma — A rare, slow-growing cancer defined by a gene fusion involving NTRK3. It occurs in both children and adults.
Mixed histologic types — Two or more types are present in meaningful amounts. The report names each type and gives the percentage of the tumor it makes up.
Other histologic type not listed — A rare type outside the list above, which the report names. Examples include tall cell carcinoma with reversed polarity and mucoepidermoid carcinoma.

Metaplastic carcinoma is reported by its specific form, because the forms behave very differently. The checklist names spindle cell, squamous cell, and one with heterologous differentiation, meaning the tumor has produced cartilage or bone. It also names two favorable forms, low-grade adenosquamous carcinoma and the fibromatosis-like form. A mixed metaplastic carcinoma contains more than one of these, and the report gives the percentage of each.

Two answers on this item are not tumor types. “No residual invasive carcinoma” means treatment before surgery cleared the invasive cancer. Microinvasion, meaning invasion measuring 1 millimeter or less, is recorded under tumor size rather than here. Some reports add a histologic type comment, which is free text the pathologist uses to explain an unusual feature.

Histologic grade (the Nottingham score)

Histologic grade describes how closely invasive breast cancer cells and the structures they form resemble normal breast tissue. Every invasive breast cancer is graded, using a system called the Nottingham histologic score. Your report may also call it the Elston-Ellis or the modified Scarff-Bloom-Richardson system.

The pathologist scores three separate features, each from 1 to 3. The three scores are added together to give a total between 3 and 9, and that total determines the grade.

Tubule formation — How much of the tumor forms gland-like tubes. Score 1 is more than 75 percent, score 2 is 10 to 75 percent, and score 3 is less than 10 percent.
Nuclear pleomorphism — How much the tumor nuclei vary in size and shape compared with normal breast cells. Score 1 is minimal variation, score 2 is mild to moderate, and score 3 is marked.
Mitotic rate — How many cells are dividing in a measured area of the busiest part of the tumor. The counts that separate score 1, 2, and 3 depend on the size of the microscope field.

The three scores are then combined into an overall grade.

Grade 1, well differentiated — A total score of 3, 4, or 5. The tumor closely resembles normal breast tissue and tends to grow slowly.
Grade 2, moderately differentiated — A total score of 6 or 7. The tumor falls between the other two.
Grade 3, poorly differentiated — A total score of 8 or 9. The tumor bears little resemblance to normal breast tissue and tends to grow faster.
Only microinvasion present — The invasive area was 1 millimeter or less, which is too small to grade reliably.
Score cannot be determined — Grading was not possible, and the report explains why. This happens most often after treatment given before surgery.

Grade is one of the strongest predictors of how a breast cancer will behave, and it holds true at every tumor size and node status. It also feeds directly into the prognostic stage group your oncologist will discuss with you. Some reports add a histologic grade comment explaining an unusual scoring decision.

Tumor size

Tumor size on a breast cancer report is the largest measurement of the invasive cancer, given in millimeters. Only the invasive part is measured. Any surrounding DCIS is excluded, and separate areas of invasion are not added together. Size is one of the two main factors determining the tumor stage, along with what the cancer has grown into.

Largest contiguous focus of invasive carcinoma — The exact measurement of the largest area of invasion, in millimeters. This is the number used for staging.
Microinvasion only — The invasion measures 1 millimeter or less. Anything larger than 1 millimeter is rounded up to 2 millimeters and is not called microinvasion.
No residual invasive carcinoma — No invasive cancer remained in the specimen, which is seen after successful treatment before surgery.
Size cannot be determined — The measurement could not be established, and the report explains why.
Sizes and locations of additional foci — An optional list of the other areas of invasion, when several with similar features were found.

One rule surprises patients whose cancer was largely removed by the needle biopsy. Where the earlier biopsy showed a larger area of invasion than the surgery did, the larger of the two is used for staging. The two are never added together, because that would overstate the true size.

Judging size is harder in the breast than it sounds. Invasive lobular carcinoma, treated cancers, and cancers next to a healing biopsy site are all difficult to measure precisely. In these cases the pathologist weighs the imaging findings, the appearance of the cut specimen, and the microscope slides together before settling on a number.

Ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ, or DCIS, is a cancer that is still confined inside the ducts. It has not broken through into the surrounding tissue, so it cannot spread. Most invasive breast cancers have some DCIS alongside them, and the checklist records it because it affects how much tissue has to be removed. The report states not identified, present, or cannot be excluded.

Where DCIS is present, the report describes how it sits in relation to the invasive cancer. It may be admixed with the invasive carcinoma, extend beyond it, or lie separate from it, and more than one of these can be true. When DCIS is admixed, the report may give it as a percentage of the whole tumor. When it extends beyond, the report may give its own size in millimeters, which helps explain a mammogram finding larger than the invasive cancer.

Three further details about the DCIS may be reported. Each is optional, so your report may include all of them or none.

Architectural pattern — How the cells are arranged inside the duct. The options are comedo, cribriform, micropapillary, papillary, and solid. Solid papillary carcinoma in situ, encapsulated papillary carcinoma, and Paget disease of the nipple are also listed here.
Nuclear grade — How abnormal the nuclei look, reported as grade I (low), grade II (intermediate), or grade III (high).
Necrosis — Areas of dead tumor cells inside the duct, reported as not identified, focal, or central. Central necrosis is also called comedo necrosis.

Nuclear grade and necrosis predict behavior better than the architectural pattern does. Neither changes the stage. When an invasive cancer is present, the DCIS does not add to the tumor size and does not raise the tumor stage. It matters instead for the margins, and for the risk that cancer comes back in the same breast.

Other lesions in the surrounding breast tissue

When breast tissue is removed for cancer, the pathologist examines the surrounding tissue as well. The checklist has an optional item for a group of findings that are not invasive cancer but are not entirely normal either. None of them changes the stage.

Lobular carcinoma in situ, classic — Abnormal cells filling the small glands without invading. It is understood as a marker of increased risk in both breasts rather than as a cancer that will spread.
Lobular carcinoma in situ, pleomorphic — A form with larger, more abnormal nuclei. It is treated more like DCIS than like the classic form, and margins are often reported for it.
Atypical lobular hyperplasia — The same abnormal cells as classic lobular carcinoma in situ, but filling less of the gland. It carries a smaller increase in risk.
Atypical ductal hyperplasia — An abnormal growth inside a duct that falls short of DCIS in either extent or appearance.
Flat epithelial atypia — A single layer of mildly abnormal cells lining a duct. It carries only a small increase in risk.
Not identified — None of these findings was present in the tissue examined.
Other — Any additional lesion, which the report names.

Where lobular carcinoma in situ is present, the report may add its extent. That detail matters most for the pleomorphic and florid forms, which some surgical teams treat differently from the classic form.

Tumor extent: the nipple, the skin, and the muscle

This item records whether the invasive breast cancer has reached the nipple, the skin, or the muscle beneath the breast. It is completed only when one of those structures was removed with the specimen. Reports mark it “not applicable” when none was included, which is common after a lumpectomy.

Nipple status — Reported as not present in the specimen, present and not involved, involved by invasive carcinoma, DCIS present in the large milk ducts, or Paget disease present. Nipple involvement does not change the tumor stage.
Skin status — Reported as not present, present and not involved, invasion into the skin without ulceration, or invasion with visible ulceration. Invasion of the skin alone does not change the stage. Visible ulceration makes the tumor stage pT4b.
Macroscopic skin satellite foci — Separate nodules of cancer in the skin, visible to the naked eye. These also make the tumor stage pT4b. Nodules found only under the microscope do not.
Skeletal muscle — Reported as not present, present and not involved, invaded by carcinoma, or invaded through to the chest wall. Only invasion deeper than the pectoralis muscle makes the tumor stage pT4a.

The distinction between what is visible to the eye and what is visible only under the microscope runs through this whole item. A change in stage requires the finding to have been seen during the operation or in the specimen before it was cut, with the microscope used to confirm it.

Lymphatic and vascular invasion

This item records whether invasive breast cancer cells were seen inside vessels in the tissue around the tumor. Vessels are one route by which cancer reaches lymph nodes and other organs, so finding cells inside one indicates they have gained access to that route. It does not mean the cancer has spread. Pathologists do not separate lymphatic channels from blood vessels here, because the distinction does not change anything.

Not identified — No tumor cells were seen inside any vessel. This is the most common answer.
Present, focal — Tumor cells were found in one or two vessels within a single block of tissue.
Present, extensive — Tumor cells were found in more than two vessels, or in vessels in two or more blocks of tissue.
Cannot be determined — The finding could not be assessed, and the report explains why.

Lymphovascular invasion does not change the tumor stage, the nodal stage, or the overall stage group in breast cancer. It is associated with a higher chance that the cancer comes back, and it is one of the findings the team weighs when discussing radiation and chemotherapy.

Where skin was included in the specimen, the report answers a second, separate question about vessels in the skin itself. Dermal lymphatic and vascular invasion is reported as not applicable, not identified, or present. This finding is recorded on its own because of what it can mean. Combined with redness and swelling across a third or more of the breast, it defines inflammatory carcinoma, which is staged pT4d. Without those clinical signs it does not change the stage.

Microcalcifications

Microcalcifications are tiny deposits of calcium in breast tissue. They are far too small to feel, but they show up clearly on a mammogram, and they are one of the main reasons a breast biopsy is recommended. This optional item records where they were found in the tissue removed.

Not identified — No calcifications were seen in the sections examined.
Present in DCIS — The calcifications lie inside ducts containing DCIS. This is the most common answer when calcifications led to the biopsy.
Present in invasive carcinoma — The calcifications lie within the invasive cancer itself.
Present in non-neoplastic tissue — The calcifications lie in normal or benign breast tissue rather than in cancer.

This item exists to confirm that the right area was removed and examined. When a surgeon operates on calcifications seen on a mammogram, an X-ray of the specimen is taken in the operating room or the laboratory. The pathologist then makes sure the calcifications on that X-ray are accounted for under the microscope.

Treatment effect after therapy given before surgery

Some patients with invasive breast cancer receive chemotherapy, HER2-targeted therapy, immunotherapy, or hormone-blocking therapy before surgery. This is called neoadjuvant or presurgical therapy, and it is now common in larger cancers and in node-positive disease. When it has been given, the pathologist describes how much living cancer is left.

No known presurgical therapy — No treatment was given beforehand. This is what most reports say.
No definite response — Treatment was given, but the tissue shows no sign of having responded.
Evidence of response — A response is visible, and the report may describe how much of the cancer is left.
No residual invasive carcinoma in the breast — Treatment cleared the invasive cancer from the breast entirely.
Cannot be determined — The response could not be assessed, and the report explains why.

Where lymph nodes were removed, a matching item describes the response in them. It states whether metastatic cancer is still present, whether it shows a response, or whether the nodes are clear. A separate answer covers nodes that are clear but contain scarring or clusters of immune cells, which may mark where a deposit responded completely.

Reports on patients treated before surgery use the letter “y” before the stage, written as ypT and ypN. It shows that the stage describes the cancer after treatment rather than before it. When no living invasive cancer remains in either the breast or the nodes, this is a complete pathologic response, recorded as ypT0 or ypTis with ypN0. A complete response is associated with substantially better long-term outcomes.

Your report may also carry a residual cancer burden score, usually shortened to RCB. It combines the area of the tumor bed, the proportion of it that is still living cancer, and the number and size of the involved nodes into one number. That number is reported as a class from RCB-0 to RCB-III. RCB-0 means no cancer remained, and RCB-III means a large amount remained. The score was designed for chemotherapy and is not used after hormone-blocking treatment alone.

Surgical margins

A margin is a surface that the surgeon cut in order to remove the breast specimen. The pathologist inks these surfaces, examines them under the microscope, and reports whether cancer reaches any of them and how close it comes. In a breast specimen the margins are usually named by direction: superior, inferior, medial, lateral, anterior, and deep.

Margins are reported twice, once for invasive carcinoma and once for DCIS, because the two are managed differently. For the invasive cancer, the report gives one of the following.

All final margins greater than 2 mm — The cancer is well clear of every cut edge. Many reports use this single line rather than listing each margin.
Invasive carcinoma within 0 to 2 mm of the final margins — The cancer comes close to at least one edge. The report then specifies the margins involved at ink, those less than 1 mm away, and those 1 to 2 mm away.
Margins involved by invasive carcinoma — Cancer cells reach the inked cut edge itself. The report names each margin involved.
Not applicable — No invasive cancer remained in the specimen to measure from.
Cannot be determined — Margin status could not be established, and the report explains why.

The same set of answers is given again for DCIS, using the same distances. The word “final” matters in both. Where the surgeon removed extra tissue at an edge during the same operation, the final margin is the outer surface of that extra tissue, not the first one.

The distances are reported in these bands because treatment teams use them. For invasive cancer treated with lumpectomy and radiation, no tumor cells at the ink is generally accepted as a clear margin. For DCIS, a distance of 2 millimeters is generally used instead. A positive or close margin informs the discussion about removing more tissue or adjusting radiation.

Cancer cells inside a vessel at the margin are not counted as an involved margin. The deep margin also needs reading with care. It sometimes lies directly on the covering of the muscle, where there is almost no breast tissue beyond it. A close deep margin in that position means less than a close margin elsewhere. Some reports add a margin comment explaining a finding of this kind.

Lymph nodes

Lymph nodes are small immune organs found throughout the body. Breast cancer reaches them in a fairly predictable order, arriving first at the nodes under the arm on the same side. Whether cancer is found in those nodes is the strongest single factor in staging breast cancer.

Most patients have a sentinel lymph node biopsy, in which the surgeon uses a dye or a tracer to find the first few nodes the breast drains into. Fewer than six nodes are removed. An axillary dissection removes a larger block of tissue, and the nodes in it are grouped by level, counted outward from the chest. Nodes found within the breast tissue itself are called intramammary nodes and are counted with the axillary ones.

Your report gives the following.

Total number of lymph nodes examined — Every node found, sentinel and non-sentinel together, given as an exact number.
Number with macrometastases — Nodes containing a deposit larger than 2 millimeters. These are the deposits that count most in staging.
Number with micrometastases — Nodes containing a deposit larger than 0.2 millimeters but no larger than 2 millimeters, or more than 200 cells.
Number with isolated tumor cells — Nodes containing single cells or clusters no larger than 0.2 millimeters, or fewer than 200 cells.
Size of the largest deposit — Measured in millimeters, across the largest group of tumor cells touching one another.
Extranodal extension — Cancer cells have broken through the outer capsule of a lymph node into the surrounding tissue. The report states not identified or present.

The three sizes of deposit are not just descriptive. Nodes containing only isolated tumor cells are counted in the total number examined but are not counted as positive nodes for staging. Nodes with micrometastases give a nodal stage of pN1mi when they are the only finding. Once a deposit larger than 2 millimeters is present anywhere, the micrometastatic nodes are counted along with it.

Extranodal extension is reported for breast cancer and may be associated with a higher risk of recurrence. It does not change the nodal stage or the overall stage group. Where it is present, the report may add its measurement and the number of nodes involved.

Distant metastasis

This item records whether invasive breast cancer was confirmed under the microscope at a site outside the breast and its nearby lymph nodes. It is completed only when tissue from that site was actually examined. Most reports mark it “not applicable,” because distant spread is usually assessed by imaging rather than by biopsy. The sites listed on the checklist are non-regional lymph nodes, the lung, the liver, bone, the brain, and other sites the report names.

Pathologic stage (pTNM)

Pathologic stage summarizes how far the invasive breast cancer had spread at the time of surgery. It is described using the TNM system from the American Joint Committee on Cancer (AJCC). Breast cancer currently uses the 8th edition. T describes the size and extent of the tumor, N describes the lymph nodes, and M describes spread to distant organs. The letter “p” in front means the category was determined by examining tissue under the microscope.

Two prefixes may appear. A “y” means the stage was assigned after treatment given before surgery. An “r” means the tumor is a recurrence, staged after a period during which no disease was detectable.

The pathologic stage on your report is not the same thing as the overall stage group, written as stage I through IV, that your oncologist will discuss with you. In breast cancer the difference is larger than in most other cancers. The stage group folds in the histologic grade and the estrogen receptor, progesterone receptor, and HER2 results as well as the T, N, and M categories.

Those biomarker results arrive on a separate report, so the stage group often cannot be assigned until after this one is issued. The treating physician assigns it, not the pathologist. A report that reads pT2 does not mean stage II.

Tumor stage (pT)

The tumor stage for breast cancer is based on the size of the invasive cancer and on what it has grown into. When both apply, the higher category is used.

pT0 — No invasive cancer remains in the specimen, seen after successful treatment before surgery.
pTis (DCIS) — Ductal carcinoma in situ with no invasive cancer.
pTis (Paget) — Paget disease of the nipple with no invasive cancer and no DCIS in the breast tissue beneath.
pT1mi — Microinvasion, meaning invasive cancer measuring 1 millimeter or less.
pT1a — Larger than 1 millimeter but not larger than 5 millimeters.
pT1b — Larger than 5 millimeters but not larger than 10 millimeters.
pT1c — Larger than 10 millimeters but not larger than 20 millimeters.
pT2 — Larger than 20 millimeters but not larger than 50 millimeters.
pT3 — Larger than 50 millimeters.
pT4a — Extension into the chest wall. Invasion of the pectoralis muscle alone does not count.
pT4b — Ulceration of the skin, satellite nodules in the skin on the same side, or swelling of the skin.
pT4c — Both pT4a and pT4b are present.
pT4d — Inflammatory carcinoma, defined by redness and swelling across a third or more of the breast skin.
Subcategory cannot be determined — The tumor is pT1 or pT4, but the material did not allow the letter to be assigned.
pT not assigned — The category could not be determined from the material available.

The letter “m” in brackets is added when more than one separate invasive cancer was present in the same breast.

Nodal stage (pN)

The nodal stage is based on how many lymph nodes contain cancer, how large the deposits are, and where the nodes sit.

pN0 — No cancer in the lymph nodes examined, or isolated tumor cells only.
pN0 (i+) — Isolated tumor cells only, meaning clusters no larger than 0.2 millimeters.
pN0 (mol+) — A molecular test detected tumor material, but no tumor cells were seen under the microscope.
pN1mi — Micrometastases only, each larger than 0.2 millimeters but none larger than 2 millimeters.
pN1a — Cancer in 1 to 3 nodes under the arm, with at least one deposit larger than 2 millimeters.
pN1b — Cancer in sentinel nodes behind the breastbone on the same side, isolated tumor cells excluded.
pN1c — pN1a and pN1b together.
pN2a — Cancer in 4 to 9 nodes under the arm, with at least one deposit larger than 2 millimeters.
pN2b — Cancer in nodes behind the breastbone seen on imaging, with the nodes under the arm clear.
pN3a — Cancer in 10 or more nodes under the arm, or in nodes beneath the collarbone.
pN3b — Cancer in nodes under the arm together with involved nodes behind the breastbone.
pN3c — Cancer in nodes above the collarbone on the same side.
pN not assigned — No nodes were submitted or found, or the category could not be determined.

Two labels may follow the nodal stage. The label “(sn)” means a sentinel node procedure was performed and fewer than six nodes were removed. The label “(f)” means the deposit was confirmed by a needle sample rather than by removing the node.

Metastasis stage (pM)

The metastasis category is completed only when spread to a distant site was confirmed by examining tissue. Otherwise the report marks it as not applicable. There is only one positive answer, pM1, meaning a deposit larger than 0.2 millimeters was confirmed under the microscope at a distant site.

Other findings in the breast

When breast tissue is removed for cancer, the pathologist examines everything else in the specimen too. The checklist has a free-text item for findings the standard items do not capture. None of these findings is cancer, and none changes the stage. Common entries include fibrocystic change, fibroadenoma, sclerosing adenosis, columnar cell change, usual ductal hyperplasia, intraductal papilloma, and radial scar.

Two entries relate to earlier procedures. Biopsy site changes are the scarring and inflammation left where the needle biopsy was taken, sometimes with fat necrosis around them. Their presence confirms that the right area was removed. The report also notes when an invasive cancer was an unexpected finding in tissue taken for something benign.

Biomarker and molecular testing

Biomarker testing looks for specific proteins and genes in an invasive breast cancer that determine which drugs are likely to work. These results are not part of the checklist described in this article. They are reported on a separate CAP template, usually issued on its own and sometimes days or weeks later. Your report may say that testing is pending, most often in the comments section at the end.

For invasive breast cancer, the tests are the estrogen receptor (ER), the progesterone receptor (PR), HER2, and Ki-67. The resection checklist carries a section headed “special studies,” where the laboratory may repeat the results already obtained from your needle biopsy. Where that happens, the report states which earlier case the results came from.

Two other kinds of testing are also reported elsewhere. Genomic assays such as Oncotype DX, MammaPrint, and Prosigna are ordered separately and are covered in our article on genomic testing in breast cancer. Inherited gene testing for BRCA1 and BRCA2 is done on a blood or saliva sample and describes you rather than the tumor.

Our guide to invasive breast cancer biomarker test results explains each of these tests, every result you might see, and what it means for treatment. You can also read about the individual tests in the Biomarkers and Genetic Testing section of this website.

What is the prognosis?

Prognosis is the expected course of a disease. The outlook for invasive breast cancer is more favorable than for most other cancers, and it has improved steadily for decades. Across all stages combined, roughly 91 out of every 100 people diagnosed with breast cancer are alive five years later.

That figure varies a great deal by how far the cancer had spread when it was found. When it is still confined to the breast, close to 99 out of 100 people are alive at five years. When it has reached nearby lymph nodes, the figure is roughly 87 out of 100. When it has spread to distant organs, it is roughly 32 out of 100.

These figures describe large groups of people diagnosed years ago and cannot predict what will happen to any one person. They also predate several treatments now in routine use. Your own outlook depends on the combination of findings in your report, above all the following.

Lymph node status — The strongest single factor. Outcomes are best when no cancer is found in the nodes, and the risk rises with the number of involved nodes.
Tumor size — A smaller invasive cancer carries a lower risk of recurrence, at every node status.
Histologic grade — Grade 1 cancers recur least often and grade 3 cancers most often. Grade holds its predictive value independently of size and node status.
Histologic type — Tubular, cribriform, mucinous, and classic lobular carcinomas carry a more favorable outlook. Metaplastic and micropapillary carcinomas carry a less favorable one.
Biomarker results — Hormone receptor and HER2 status shape both the outlook and the treatment options, which is why they are folded into the stage group.
Lymphovascular invasion — Associated with a higher risk of recurrence, though it does not change the stage.
Margin status — Cancer at a cut edge raises the risk that disease remains in the breast.
Response to treatment given before surgery — Where presurgical treatment was given, a complete response is associated with substantially better long-term outcomes.

What happens after this diagnosis?

The pathology report from your breast operation is the document your treatment team uses to plan what comes next. Care is coordinated by a group that typically includes a breast surgeon, a medical oncologist, a radiation oncologist, a pathologist, and a radiologist. They often review reports together at a tumor board meeting.

The findings on your report shape several decisions.

Radiation — Considered after almost every lumpectomy. After a mastectomy it is considered when nodes contain cancer, when the tumor was large, or when a margin was involved.
Further surgery — An involved or close margin may lead to a discussion about removing more tissue. A positive sentinel node may lead to a discussion about the remaining nodes.
Hormone-blocking therapy — Considered when the estrogen or progesterone receptor result is positive. It is taken as a tablet or injection for a period of years.
HER2-targeted therapy — Considered when the HER2 result is positive, and given with chemotherapy.
Chemotherapy — Considered based on stage, grade, and the biomarker results together. In hormone receptor positive, HER2 negative cancers, a genomic assay is often used to inform the decision.
Genetic counseling — Considered based on your age, your family history, and the type of cancer. A referral does not depend on anything in this report alone.
Follow-up — Regular examination and imaging of the remaining breast tissue for several years, along with attention to the side effects of any ongoing treatment.

If any part of your report is unclear, your treating physician can request the full report from the laboratory and go through it with you. A second opinion on the pathology can also be arranged if you would like one.

Questions to ask your doctor

What type of invasive breast cancer do I have, and what does that type mean for my treatment?
What was the size of the invasive cancer on my report, and what tumor stage did it give?
What was my Nottingham histologic grade, and what does that grade mean for me?
Was ductal carcinoma in situ present, and did it change how much tissue had to be removed?
Was my tumor unifocal or multifocal, and did that affect the operation I had?
Were all my margins clear, and how close did the cancer come to the closest one?
How many lymph nodes were examined, and how many contained cancer?
Were the deposits in my nodes macrometastases, micrometastases, or isolated tumor cells?
Does my report say that lymphatic or vascular invasion was present?
Have my estrogen receptor, progesterone receptor, and HER2 results come back yet?
What is my overall stage group, and how does it relate to the pT and pN on my report?
If I had treatment before surgery, how much living cancer was left in the breast and the nodes?
Does anything on my report make radiation, chemotherapy, or hormone-blocking therapy an option for me?
Should I be referred for genetic counseling, and what would that involve?