Grading and staging of uterine cancer are done to show the aggressiveness of the cancer, its extent and spread, and are important gradients for prognosis (outlook) and survival rate, as well as for deciding on the best treatment plan.
Grading of Uterine Cancer
Grading helps to determine how much the tumor tissue differs from normal uterine tissue. It can help to indicate which tumors are more likely to grow rapidly. Grade indicates aggressiveness of the cancer. Tumors with higher grades usually grow more rapidly, are more likely to metastasize and recur after treatment.
Grading of a tumor is useful in deciding the type of treatment that will be most suitable for that particular patient. It is done by examining the tissue samples from the uterus under a microscope.
- Grade 1 (low grade) – the cells are quite similar to normal endometrial cells and are said to be “well-differentiated”. They are usually slow-growing and are least aggressive.
- Grade 2 (middle grade) – this is the intermediate grade.
- Grade 3 (high grade) – the cells look abnormal and are said to be “poorly-differentiated”. These cells grow rapidly and are most aggressive.
Staging of Uterine Cancer
Staging of a cancer is important in deciding on the best treatment options. It also indicates the outcome of the disease. Staging is a system that helps to determine how far the cancer has spread, whether it is limited to the nearby tissues or has spread to distant tissues and organs. The cancer may spread :
- Locally to other parts of the uterus.
- Regionally to nearby lymph nodes in the pelvis and the lymph nodes along the aorta.
- Metastasize to distant lymph nodes or organs such as lungs, liver and brain.
For staging of uterine cancer certain tests may be helpful, such as :
- Pap test to see if cancer has spread to the cervix.
- Chest x-ray to see if the lungs are involved.
- CT scan or MRI can diagnose spread of cancer to different organs.
Another method of staging of uterine cancer is known as surgical staging. It is a post-operative procedure where the staging is done based on examination of tissue removed during operation. This includes tissue samples taken from the pelvis and abdomen, and the uterus (which may be cut open to see the extent of growth).
Either way, staging is done on the basis of these 3 factors :
- The extent of tumor (T).
- Whether the cancer has spread to lymph nodes (N).
- Whether the cancer has spread to distant sites (M).
Tumor Extent (T)
- T0 – there is no sign of cancerous growth in the uterus.
- Tis – cancer-in-situ or pre-invasive cancer – only the surface layer of the endometrium shows cancerous cells, with no involvement of the deeper layers.
- T1 – the cancer is restricted to the body of the uterus.
- T2 – the cancer has spread from the body of the uterus to the supporting connective tissue of the cervix, but has not spread outside the uterus.
- T3 – the cancer has spread outside the uterus but has not reached the inner lining of the bladder or rectum.
- T3a – the cancer has reached the outer layer of the uterus and/or the fallopian tubes and ovaries.
- T3b – the cancer has spread to the vagina or the tissues around the uterus.
- T4 – the cancer has spread to the inner lining of the bladder or rectum.
Lymph Node Spread (N)
- NX – spread of cancer to nearby lymph nodes cannot be assessed.
- N0 – there is no spread of cancer to nearby lymph nodes.
- N1 – the cancer has spread to the pelvic lymph nodes.
- N2 – the cancer has spread to lymph nodes along the aorta.
Distant Spread or Metastasis (M)
- M0 – the cancer has not spread to distant lymph nodes, tissues or organs.
- M1 – the cancer has spread to distant organs such as the lungs, liver or brain.
Staging is done by compiling all the information together about tumor extent, spread to lymph nodes, and distant spread of cancer. Thus, endometrial cancer can be classified into the following stages :
- Stage 0 – carcinoma in situ where cancer cells are found only on the surface layer of the endometrium.
- Stage 1 – the tumor has grown through the endometrium and may have invaded the muscle layer of the uterus.
- Stage 2 – the tumor has invaded the cervix.
- Stage 3 – the tumor has grown through the uterus to invade nearby tissues such as the vagina or the pelvic lymph nodes.
- Stage 4 – the tumor has invaded the bladder or bowel, or has reached distant sites such as the lungs, liver, brain or bones.
Survival Rate and Prognosis in Uterine Cancer
The prognosis or outlook for patients with uterine cancer is referred to as their survival rate. It is generally discussed as the 5-year survival rate, which is the percentage of women who live at least 5 years after the cancer is diagnosed. This includes patients who live much longer than 5 years.
The 5-year survival rates are determined by follow-up of a large number of patients for more than 5 years. This gives only an approximate estimate since newer treatments for cancer can improve the rate. Individual factors also need to be considered and one woman’s response to treatment can vary greatly from another woman’s. Many other factors are also involved, such as the health of a person at the time of diagnosis and the type of cancer.
The 5-year survival rate for endometrial cancer which has not spread can be as high as 95%. Spread to distant organs results in a sharp fall in 5-year survival rate, which can be as low as 23% or even less. Due to increasing patient awareness about the early signs and symptoms of endometrial cancer, and as a result of early cancer detection in most cases, the outcome is usually good.
- The prognosis of patients with Type 1 endometrial cancer – a slow-growing cancer, said to be dependent on estrogen – is very good as it is usually detected early.
- Type 2 endometrial cancer, which is fast-growing and more aggressive than the Type 1 variety, is more often detected at an advanced stage hence the outlook is more grim in these cases.
Read more on types of uterine cancer.
Recurrence of uterine cancer even after successful treatment is a possibility and most recurrences occur within 2 years. Usually, low grade tumors are less likely to metastasize or recur after treatment. Recurrence in early-stage disease is most often seen at the vaginal cuff and pelvis. Surgical excision, radiation therapy, or a combination of both may be done in these cases.
Endometrial cancer treated with surgery alone tends to show recurrences confined to the pelvis, whereas treatment done with surgery and radiotherapy are more likely to show less localized recurrences with more involvement of the lungs, liver, bones, brain, abdomen, and lymph nodes. Surgical excision and radiation therapy are less effective in these cases, and hormone therapy or chemotherapy may give better results.