by Jason Wasserman MD PhD FRCPC
March 18, 2022
Squamous cell carcinoma is a type of cervical cancer. The tumour starts from specialized squamous cells normally found on the surface of the cervix. Most tumours start from a pre-cancerous disease called high grade squamous intraepithelial lesion (HSIL).
The most common cause of squamous cell carcinoma in the cervix is infection with a sexually transmitted virus called human papillomavirus (HPV).
The diagnosis of squamous cell carcinoma is usually made after cells are removed from the cervix during a procedure called a Pap test. The diagnosis can also be made after a larger sample of tissue is removed in a biopsy or resection.
After the entire tumour has been removed, your pathologist will make careful measurements to determine the tumour size. The tumour size is important because it is used to determine the pathologic tumour stage (see Pathologic stage below). Larger tumours are more likely to spread to nearby organs and to other parts of the body such as lymph nodes.
Most reports describe the tumour in three dimensions:
Tumour extension describes the distance the cancer cells have travelled from where the tumour started 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.
Your pathologist can only determine the tumour extension after the entire tumour has been removed. It will not be described in your report after a pap smear or a biopsy. Tumour extension into the parametrium or other organs around the cervix is associated with a 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 the stroma. Pathologists describe the movement of cancer cells from the epithelium into the stroma as 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 the stromal invasion.
The amount of stromal invasion is important because it is used to determine the tumour stage (see Pathologic stage below). In general, less stromal invasion is associated with a better prognosis while more invasion is associated with a 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 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. 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.
A margin is called negative if there are no cancer cells at the cut edge of the tissue. In contrast, 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 number and type of margins described in your report will depend on the type of procedure performed to remove the tumour from your body. Pap smears do not have margins.
Common margins include:
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 a worse prognosis.
Squamous cell carcinoma is given a 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.