Stages of Endometrial Cancer

If malignant cells are found in the lining of the uterus (the endometrium), your doctor will diagnose endometrial cancer. One of the first things your specialist will want to do is stage your cancer so that he/she knows how extensive your tumour is and whether or not your cancer has spread beyond the endometrium. Determining the stage of cancer will enable your doctor to plan the optimal treatment approach.

How is endometrial cancer staged?

There are a number of tools available to enable a doctor to assess what stage a cancer is at. They will probably start by performing a pelvic exam and a Pap smear. This will determine whether the cancer has spread within the pelvis and to the cervix. Your doctor will also use various imaging tests, including x-rays, CT scans, MRIs and PET scans, to determine whether there are cancer cells elsewhere in the body. If the primary cancer has spread beyond the endometrium, it is known as metastatic disease.

In the process of staging your cancer, the doctor will also perform a lymph node dissection, taking nodes from the pelvic region. The lymph system is one way in which cancer spreads to other regions in the body. Cancer can also spread through the circulation and across adjacent tissues. This is why endometrial cancer will often spread to other organs within the pelvic region before it spreads elsewhere.

What are the stages of endometrial cancer?

Endometrial cancer is staged from I-IV. It is also classified based on tumour size (T), spread to nearby lymph nodes (N) and metastatic spread (M).

Stage I (T1, N0, M0): The cancer remains within the uterus
Stage IA – Cancer detected in the endometrium and less than halfway through the myometrium (the muscular layer of the uterus).
Stage IB – Cancer detected halfway or more through the myometrium, but not beyond the uterus.

Stage II (T2, N0, M0): Cancer detected in the connective tissue of the cervix (the cervical stroma), but not beyond the uterus.

Stage III (T3, N0, M0): Cancer has spread beyond the uterus and cervix, but not outside of the pelvis. No cancer detected in the inner lining of the rectum or the bladder.
Stage IIIA – Cancer detected in the outer layer of the uterus and/or the fallopian tubes, the ovaries and the ligaments of the uterus.
Stage IIIB – Cancer has spread to the vagina and/or the parametrium (connective tissue and fat surrounding the uterus).
Stage IIIC (T1-3, N1 or N2, M0) – Cancer detected in the lymph nodes in the pelvis (N1) and/or those that surround the aorta (N2). No cancer detected in distant lymph nodes.

Stage IV: Cancer has spread beyond the pelvis.
Stage IVA (T4, any N, M0) – Cancer detected in the bladder and/or rectum lining (bowel).
Stage IVB (Any T, any N, M1) – Cancer has spread to other parts of the body, including the abdomen and/or the lymph nodes in the groin (inguinal nodes). Frequent metastatic sites are the lungs, liver and bones.

What distinguishes low risk endometrial cancer from high risk endometrial cancer?

Accurate staging also enables your doctor to determine whether your endometrial cancer is considered to be high risk or low risk.

Tumours that are graded T1 or T2 are usually considered low risk. They rarely spread to other regions. Tumours that are graded T3 or above are considered high risk. Examples of high risk endometrial cancers include uterine papillary serous, clear cell carcinoma and carcinosarcoma. These types of cancer have a higher risk of spreading to other regions.

High risk cancer is more challenging to treat and is associated with a worse prognosis. Recurrent cancer can also prove more difficult to manage. This is when cancer returns after initial treatment.

What next?

Your doctor will use the results of your staging assessment to determine which treatment approaches to take. The most common options include:

• Surgery. Most often a total or radical hysterectomy and oophorectomy. A total hysterectomy removes the uterus and cervix; a radical hysterectomy (used for high risk cancers, at stage III and IV) also removes the vagina. An oophorectomy removes the ovaries and fallopian tubes. Lymph nodes from within the pelvis may also be taken.
• Radiotherapy. This can be given internally, whereby a radioactive substance is delivered to the tumour site via needles, catheters or wires; or externally, with radiation being directed at the tumour from outside the body.
• Chemotherapy. The specific drugs used will depend on the stage of the cancer.

For endometrial cancer that is classified as stage III or stage IV, there is also the option for hormone or targeted therapy. When a cancer is designated as hormonally-responsive, hormone therapy can be used to inhibit the hormonal activity and thereby prevent the growth of cancer cells. Targeted therapy acts specifically on cancer cells, stopping their growth and replication, whilst sparing the adjacent healthy cells. The two main types are mTOR inhibitors and monoclonal antibodies.

Following a diagnosis of endometrial cancer, your doctor will discuss all of these options with you.

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Sources:

• “Endometrial Cancer Stages.” American Cancer Society, https://www.cancer.org/cancer/endometrial-cancer/detection-diagnosis-staging/staging.html.
• “Endometrial Cancer Treatment (PDQ®)–Patient Version.” National Cancer Institute, https://www.cancer.gov/types/uterine/patient/endometrial-treatment-pdq.
• Freeman, Susan J., et al. “The Revised FIGO Staging System for Uterine Malignancies: Implications for MR Imaging.” RadioGraphics, vol. 32, no. 6, Oct. 2012, pp. 1805–1827., doi:10.1148/rg.326125519.