Invasive ductal carcinoma with apocrine features is a rare type of breast cancer, making up about 1% of all breast cancers. It consists of large, pink cells that closely resemble those of apocrine sweat glands in the skin. This same cancer is also called invasive apocrine carcinoma, and the name that appears on your report may depend on the pathologist and the region. Both names describe the same diagnosis.
What sets this cancer apart from most other breast cancers is its biomarker profile: it is usually negative for the estrogen and progesterone receptors and positive for the androgen receptor (AR). This means it is generally not treated with the standard hormone-blocking therapies used for most breast cancers, and other treatment approaches are considered instead. This article will help you understand the findings in your pathology report, what each term means, and why it matters for your care.
The exact cause is not fully understood. Like other breast cancers, invasive ductal carcinoma with apocrine features develops after genetic changes occur in breast cells. Unlike most breast cancers, this tumor is driven by androgen receptor signaling rather than estrogen signaling, suggesting that androgens (male hormones such as testosterone, present in both men and women) play a role in its growth. General breast cancer risk factors such as increasing age, obesity, alcohol use, and inherited gene changes (including BRCA1 and BRCA2) may contribute, but many cases arise without a clear cause.
Like other types of invasive breast cancer, invasive ductal carcinoma with apocrine features may appear as a lump in the breast, a change in breast shape or texture, skin dimpling, or nipple discharge. It is sometimes found on a screening mammogram before symptoms develop. These symptoms are not specific to this tumor and can occur with any type of breast cancer.
The diagnosis is usually made after a small sample of the tumor is removed by biopsy, or after the tumor is removed by surgery and examined under the microscope by a pathologist. Under the microscope, the tumor consists of large cells with abundant pink cytoplasm (the cell body). The cytoplasm appears pink because it takes up eosin, one of the two dyes in the standard hematoxylin and eosin (H&E) stain. The cell nucleus is typically large and round, with prominent nucleoli (the dark spots inside the nucleus).
To confirm the diagnosis and to separate this tumor from other breast cancers and from benign apocrine changes in the breast, the pathologist performs immunohistochemistry (IHC). The characteristic pattern is strong positivity for the androgen receptor (AR), combined with absence of the estrogen and progesterone receptors. Because AR and HER2 results also guide treatment, they are described in more detail in the biomarker section below. After the diagnosis is made, imaging of the breast is used to measure the size and extent of the tumor and to plan treatment.
The Nottingham histologic grade describes how the tumor is likely to behave, based on how closely the cancer cells resemble normal breast tissue and how quickly they are growing. The pathologist scores three features, each from 1 to 3:
The three scores are added together (total 3 to 9) to give grade 1 (score 3 to 5, low grade), grade 2 (score 6 or 7, intermediate grade), or grade 3 (score 8 or 9, high grade). Because apocrine cells naturally have large nuclei with prominent nucleoli, these tumors are most often grade 2 or 3. A higher grade is associated with a higher risk of spread and recurrence.
The size of the tumor is used to determine the pathologic tumor stage (pT) and is an important predictor of outcome; larger tumors are more likely to metastasize (spread) to lymph nodes and other parts of the body. The final size can only be measured after the entire tumor has been removed at surgery, so it does not appear in a biopsy report.
Invasive ductal carcinoma with apocrine features begins inside the breast, but the tumor can grow into the overlying skin or the muscles of the chest wall. This is called tumor extension. Its presence is associated with a higher risk of local recurrence and of spread to distant sites, and it raises the pathologic tumor stage to pT4.
Lymphovascular invasion (LVI) means cancer cells have entered small blood vessels or lymphatic channels near the tumor. Once inside these channels, the cells can travel to lymph nodes or reach distant organs through the bloodstream. The pathologist reports lymphovascular invasion as “present” or “absent.” When present, it is associated with a higher risk of recurrence and metastasis, and it may influence decisions about additional treatment such as chemotherapy or radiation therapy.
A margin is the edge of the tissue removed during surgery. The pathologist examines the margins to determine whether the entire tumor was removed. Margins are assessed only after surgery that removes the whole tumor, not after a biopsy.
Lymph nodes are small immune organs that filter fluid and can trap cancer cells. When breast cancer spreads, it usually travels first to the axillary lymph nodes (under the arm). During surgery, a sentinel lymph node biopsy or a more complete removal of axillary nodes may be performed to check for spread. The report includes the number of nodes examined, the number that contain cancer, and the size of the largest deposit. It may also mention extranodal extension, meaning cancer has broken through the outer capsule of a node into the surrounding tissue.
Biomarker testing is central to the care of invasive ductal carcinoma with apocrine features, and its biomarker profile is what sets this tumor apart from most other breast cancers.
The androgen receptor (AR) is a protein in cells that enables them to respond to androgens, male hormones such as testosterone, which are present in both men and women. Normal apocrine cells make AR, and most of these tumors keep strong, widespread AR expression, so AR positivity is one of the features that confirm the apocrine nature of the cancer. AR is assessed by immunohistochemistry, and the report states the percentage of cells staining and the staining intensity. AR positivity is also of interest in treatment: drugs that block androgen signaling, such as bicalutamide and enzalutamide, are being studied in clinical trials for AR-positive, estrogen receptor-negative breast cancers. These are not yet a standard treatment for breast cancer, but your oncologist may discuss whether a clinical trial is an option.
The estrogen receptor (ER) and progesterone receptor (PR) are proteins that allow some breast cancer cells to grow in response to the hormones estrogen and progesterone. Invasive ductal carcinoma with apocrine features is characteristically negative for both. This is one of its defining features and means the tumor does not respond to standard hormone-blocking therapies such as tamoxifen or aromatase inhibitors. ER and PR are assessed by immunohistochemistry and reported as the percentage of positive cells and their staining intensity; a result is considered positive when at least 1% of cells stain. If your report shows some ER or PR positivity, it may indicate a mixed tumor that also contains non-apocrine areas.
HER2 is a protein that helps control cell growth. In some breast cancers, the HER2 gene is amplified and the cells make too much HER2 protein. HER2 is amplified more often in apocrine-type tumors than in most other breast cancers, so testing is especially important here. HER2 is tested first by immunohistochemistry (reported as 0, 1+, 2+, or 3+), with fluorescence in situ hybridization (FISH) used to settle a borderline 2+ result. A result of 3+ or FISH-amplified is HER2-positive and can be treated with HER2-targeted drugs such as trastuzumab, pertuzumab, and trastuzumab-deruxtecan. A result of 1+ or 2+/FISH-negative is HER2-low, which may respond to trastuzumab-deruxtecan in the metastatic setting. A result of 0 is HER2-negative.
When the tumor is triple-negative (ER-negative, PR-negative, and HER2-negative), PD-L1 testing by immunohistochemistry (reported as a Combined Positive Score, generally 10 or higher) helps determine eligibility for the immunotherapy drug pembrolizumab. You can read more in our overview of PD-L1 testing in cancer.
Genomic tests such as the 21-gene recurrence score (Oncotype DX) are validated mainly for hormone receptor-positive, HER2-negative breast cancer, so they are usually not applicable to this ER/PR-negative tumor. For more information, visit our Biomarkers and Genetic Testing section.
If you received chemotherapy or targeted therapy before surgery (called neoadjuvant therapy), the pathologist examines the removed tissue and lymph nodes to see how much tumor is still alive (viable). A larger treatment effect, meaning little or no viable tumor remains, is associated with better outcomes. Many centers summarize this as a residual cancer burden (RCB) index, which combines tumor bed size, remaining cancer volume, and lymph node involvement into a single score ranging from RCB-0 (no residual invasive cancer, the most favorable result) to RCB-III (extensive residual cancer).
Invasive ductal carcinoma with apocrine features is staged using the TNM system of the American Joint Committee on Cancer (AJCC), 8th edition, based on the tumor (T), lymph nodes (N), and distant metastasis (M). The pathologist determines the pT and pN stages from the removed tissue; the M stage is determined by imaging.
Stage for stage, the prognosis for invasive ductal carcinoma with apocrine features is generally similar to that of other invasive breast cancers of the same size and grade. Outcome is determined by the same major factors: tumor size, lymph node involvement, margin status, grade, and whether the cancer has spread to distant organs. Several features specific to this tumor are worth keeping in mind:
After this diagnosis, care is usually coordinated by a team that may include a breast surgeon, a medical oncologist, a radiation oncologist, and a pathologist. The pathology findings guide which options the team considers, rather than dictating a single path. Surgery removes the tumor, either by breast-conserving surgery (lumpectomy) or removal of the whole breast (mastectomy), and lymph nodes are usually sampled at the same time. Radiation therapy is often considered after breast-conserving surgery and sometimes after mastectomy.
Systemic treatment is guided by the biomarker results. Because the tumor is ER/PR-negative, hormone-blocking therapy is generally not used. HER2-targeted therapy is considered when the cancer is HER2-positive, typically in combination with chemotherapy. Chemotherapy is considered based on stage, grade, and node status. For AR-positive tumors, androgen-blocking therapy may be available through a clinical trial, and for triple-negative tumors, immunotherapy may be considered when PD-L1 is positive. After treatment, follow-up includes regular examinations and imaging to watch for recurrence.