This article will help you read and understand your pathology report for squamous cell carcinoma of the cervix.
by Jason Wasserman, MD PhD FRCPC, updated December 28, 2020
The cervix is part of the female genital tract. It is found at the bottom of the uterus where it forms an opening into the endometrial cavity. The cervix is lined by specialized cells called squamous cells that form a barrier on the surface of the cervix called an epithelium. The tissue below the epithelium is called the stroma.
Squamous cell carcinoma is a type of cancer that develops in the cervix from the squamous cells in the epithelium. Most of the time squamous cell carcinoma develops from a pre-cancerous disease called high grade squamous intraepithelial lesion (HSIL).
In HSIL the abnormal cells are seen only in the epithelium of the cervix. Squamous cell carcinoma develops when the abnormal cells spread from the epithelium into the stroma below. The spread of cancer cells into the stroma is called invasion.
Once cancer cells enter the stroma they are able to spread to other parts of the body such as lymph nodes. The movement of cancer cells from the tumour to a different part of the body is called metastasis.
Almost all cases of squamous cell carcinoma and HSIL in the cervix are a result of the normal squamous cells in the cervix becoming infected with a high risk type of virus called human papillomavirus (HPV). Pathologists often indirectly look for HPV by performing a test called immunohistochemistry for a protein called p16. Cells infected with HPV will be positive for p16.
The diagnosis of squamous cell carcinoma is usually made after a small sample of tissue is removed from the cervix during a Pap test. The diagnosis can also be made after a larger sample of tissue is removed in a biopsy or resection.
After the initial diagnosis, most patients will be offered surgery to remove the entire tumour. The tumour will then be sent to a pathologist for examination under the microscope.
This is the size of the tumour, measured in three dimensions. The size of the tumour cannot be measured on tissue from a pap smear.
The size of the tumour is used to determine the tumour stage (see Pathologic stage below).
Larger samples of tissue are usually sent for pathological examination as a single piece of tissue and the tissue is then divided into multiple sections before being examined under the microscope. Your pathologist will describe the number of pieces (or ‘blocks’ as they are often called) that show squamous cell carcinoma or HSIL in your report.
For example, your report may say “3 out of 14 blocks are positive for squamous cell carcinoma” which means that 3 out of the 14 pieces of tissue examined contain cancer.
Tumour extension describes the distance the cancer cells have traveled from their starting point in the cervix. All tumours start in the cervix however larger tumours can grow to involve the endometrium, vagina, bladder, or rectum.
The soft tissue that surrounds and support the cervix is called the parametrium. This tissue will be carefully examined for cancer cells.
Tumour extension into the parametrium or other organs around the cervix is associated with worse prognosis and is used to determine the tumour stage (see Pathologic stage below).
The squamous cells at the surface of the cervix form a barrier called the epithelium. The tissue below the epithelium is called stroma. When cancer cells enter the stroma it is called stromal invasion.
After examining your tissue sample, your pathologist will measure the amount of stromal invasion in two directions:
The size of stromal invasion is not the same as the tumour size because the tumour size also includes any HSIL that may be above the area of invasion. For that reason the size of the tumour may be larger than the size of stromal invasion.
The amount of stromal invasion is used to determine the tumour stage (see Pathologic stage below). In general, less stromal invasion is associated with better prognosis while more invasion is associated with worse prognosis.
Blood moves around the body through long thin tubes called blood vessels. Another type of fluid called lymph which contains waste and immune cells moves around the body through lymphatic channels.
Cancer cells can use blood vessels and lymphatics to travel away from the tumour to other parts of the body. The movement of cancer cells from the tumour to another part of the body is called metastasis.
Before cancer cells can metastasize, they need to enter a blood vessel or lymphatic. This is called lymphovascular invasion. Lymphovascular invasion increases the risk that cancer cells will be found in a lymph node or a distant part of the body such as the lungs.
Lymph nodes are small immune organs located throughout the body. Cancer cells can travel from the tumour to a lymph node through lymphatic channels located in and around the tumour (see Lymphovascular invasion above). The movement of cancer cells from the tumour to a lymph node is called a metastasis.
Your pathologist will carefully examine all lymph nodes for cancer cells. Lymph nodes that contain cancer cells are often called positive while those that do not contain any cancer cells are called negative. Most reports include the total number of lymph nodes examined and the number, if any, that contain cancer cells.
Lymph nodes on the same side as the tumour are called ipsilateral while those on the opposite side of the tumour are called contralateral.
Lymph nodes examined are usually divided into those found in the pelvis and those found around a large blood vessel in the abdomen called the aorta. The lymph nodes found around the aorta are called para-aortic.
If cancer cells are found in a lymph node, the size of the area involved by cancer will be measured and described in your report.
Cancer cells found in a lymph node is associated with a higher risk that the cancer cells will be found in other lymph nodes or in a distant organ such as the lungs. The number of lymph nodes with cancer cells is also used to determine the nodal stage (see Pathologic stage below).
A margin is any tissue that has to be cut by the surgeon in order to remove the tumour from your body. Pap smears do not have margins.
If you underwent a surgical procedure to remove the entire tumour from your body, your pathologist will examine the margin closely to make sure there are no cancer cells at the cut edge of the tissue.
The number and type of margins will depend on the type of procedure performed to remove the tumour from your body.
A margin is considered positive when the cancer cells are seen at the edge of the cut tissue. If HSIL is seen at the margin that will also be described in your report.
Finding cancer cells at the margin increases the risk that the tumour will grow back in that location.
The pathologic stage for squamous cell carcinoma of the cervix is based on the TNM staging system, an internationally recognized system originally created by the American Joint Committee on Cancer.
This system uses information about the primary tumour (T), lymph nodes (N), and distant metastatic disease (M) to determine the complete pathologic stage (pTNM). Your pathologist will examine the tissue submitted and give each part a number. In general, a higher number means more advanced disease and worse prognosis.
Squamous cell carcinoma is given an metastatic stage of 0 or 1 based on the presence of cancer cells at a distant site in the body (for example the lungs). The metastatic stage can only be determined if tissue from a distant site is submitted for pathological examination. Because this tissue is rarely present, the metastatic stage cannot be determined and is listed as pMX.