Learning you have ovarian cancer can feel overwhelming and raise many questions about what comes next. Understanding how doctors evaluate your cancer can help you feel more informed and in control of your care.

Once ovarian cancer is diagnosed, it’s graded and staged. The grade describes how the cancer cells look under a microscope compared to healthy cells. The stage describes how large the tumor is and how far the cancer has spread in your body. Both grading and staging can help an oncologist (cancer specialist) predict your likely outcome and choose the treatment options that may work best for you.

Ovarian Cancer Grades

A tumor’s grade describes how much its cells look like healthy, mature cells or how abnormal they appear. Healthy cells that are fully mature and have a specific role in the body are called “differentiated.” Cancer cells that are more immature and look less like normal cells are called “undifferentiated.”

To find out the tumor’s grade, a healthcare provider — usually a gynecologist or oncology surgeon — will take a biopsy (a small tissue sample) of the tumor. A pathologist (a doctor who studies cells and tissues) will look at the sample under a microscope to see how differentiated the cells are and assign a grade:

• Grade 1 — The cells are well differentiated and mostly look like normal ovarian cells.
• Grade 2 — The cells are moderately differentiated, showing a mix of normal and abnormal features.
• Grade 3 — The cells are poorly differentiated or undifferentiated, and they look mostly abnormal.

Some types of ovarian cancer may not receive a numbered grade. For example, with serous carcinoma of the ovary (a common type of epithelial ovarian cancer), tumors are classified as either “high-grade” or “low-grade” instead of numbered. Some ovarian tumors are described as “borderline,” which means they are not clearly cancer but have the potential to become cancer. Borderline tumors usually do not spread and are less likely to be harmful.

Stages of Ovarian Cancer

A cancer’s stage describes how much the cancer has spread and where it is located in the body. To determine the stage of ovarian cancer, a healthcare provider usually uses a process called surgical staging or pathological staging. In this process, an oncology surgeon or gynecologic oncologist removes the tumor, and a pathologist analyzes the tissue to assign a stage.

For people who are not able to have surgery, doctors may assign a stage based on a physical exam and imaging tests, such as a CT scan. This is called clinical staging.

There are different systems for describing a tumor’s stage. The FIGO staging system was developed by the International Federation of Gynecology and Obstetrics. It uses numbers and sometimes letters, ranging from stage 1 (the earliest stage) to stage 4 (the most advanced stage). Stages are sometimes written with Roman numerals — for example, stage III means stage 3.

Another system is the TNM staging system, created by the American Joint Committee on Cancer. It uses the letters T, N, and M to describe different characteristics of the cancer.

• T, which stands for “tumor,” describes the size of the main tumor — for example, T1, T2, T3, or T4, with higher numbers indicating a larger or more extensive tumor. Sometimes, additional letters (like T1A or T1B) give more detail.
• N stands for “node” and shows whether the cancer has spread to nearby lymph nodes (small glands that help filter out harmful substances). If no cancer is found in the lymph nodes, it’s called N0, whereas if cancer is present, it’s called N1.
• M stands for “metastasis,” which refers to whether the cancer has spread to other parts of the body. M0 means the cancer has not spread, while M1 means it has spread (metastasized).

Doctors may describe ovarian cancer using either or both of these systems, and both are designed to communicate how far the cancer has progressed. Cancers of the peritoneum (the tissue lining the abdominal wall and covering most pelvic organs) and fallopian tubes are also staged using these systems, since they behave similarly to ovarian cancer.

1. Stage 1 Ovarian Cancer

In stage 1 ovarian cancer, there is a tumor in one or both ovaries or fallopian tubes. This stage of cancer can also be described as T1-N0-M0, meaning the cancer is limited to the ovaries and/or fallopian tubes, with no cancer cells in lymph nodes and no metastasis to distant sites.

Stage 1 ovarian cancer can be further divided into substages to provide more detail:

• Stage 1A (T1A-N0-M0) — Cancer is only in one ovary or one fallopian tube. The cancer is only on the inside, not on the outside surface.
• Stage 1B (T1B-N0-M0) — Cancer is in both ovaries or both fallopian tubes. Again, the cancer is only on the inside, not on the outside of these organs. No cancer cells are found in other places in the body.
• Stage 1C (T1C-N0-M0) — Cancer is in one or both ovaries or fallopian tubes, and no cancer is found elsewhere in the body.

Stage 1C can be further divided based on specific features:

• Stage 1C1 — The tissue around the tumor (the capsule) broke open during surgery, which might let cancer cells escape into the body.
• Stage 1C2 — The capsule broke open before surgery, or there is cancer on the outside surface of the ovary or fallopian tube.
• Stage 1C3 — Cancer cells are found in fluid taken from inside the abdomen.

2. Stage 2 Ovarian Cancer

In stage 2 ovarian cancer, there is a tumor in one or both ovaries or fallopian tubes, and cancer has spread to other organs within the pelvis. There is no spread of cancer cells to lymph nodes or to distant parts of the body. This stage may also be written as T2-N0-M0.

Stage 2 disease can be further divided as:

• Stage 2A (T2A-N0-M0) — Cancer has spread from the ovary to the fallopian tube, or vice versa, or has spread to the uterus. There is no cancer in lymph nodes or other parts of the body.
• Stage 2B (T2B-N0-M0) — Cancer has spread to other nearby pelvic organs, such as the bladder or rectum. There is still no cancer in lymph nodes or distant locations.

3. Stage 3 Ovarian Cancer

In stage 3 ovarian cancer, cancer has spread outside the pelvic area. A person may also be diagnosed with stage 3 if cancer cells have spread to nearby lymph nodes in the abdomen, or if there is a tumor that started in the peritoneum.

Stage 3 ovarian cancer may be subdivided as:

• Stage 3A1 (T1-N1-M0 or T2-N1-M0) — One or both ovaries or fallopian tubes has cancer. Cancer is found in nearby lymph nodes. This stage is also further broken down into 3A1(i), which means that the metastasis in the lymph node is up to 10 millimeters in greatest dimension, and 3A1(ii), where the metastasis is more than 10 millimeters in greatest dimension.
• Stage 3A2 (T3A-N0-M0 or T3A-N1-M0) — One or both ovaries or fallopian tubes has cancer, and it has spread outside of the pelvic area. There may or may not be cancer in the nearby lymph nodes, but the pathologist confirmed the presence of cancer cells in peritoneum tissue after the surgery.
• Stage 3B (T3B-N0-M0 or T3B-N1-M0) — Cancer has spread from the ovaries or fallopian tubes to other places inside the abdomen, but the new tumors are under 2 centimeters. People with or without cancer cells in the lymph nodes are included in this category. There is no spread of cancer to more distant organs.
• Stage 3C (T3C-N0-M0 or T3C-N1-M0) — Cancer has spread from the ovaries or fallopian tubes to other places in the abdomen, such as the outside of the liver or spleen, and the tumors are larger than 2 centimeters. There may be cancer cells in nearby lymph nodes.

4. Stage 4 Ovarian Cancer

Stage 4 ovarian cancer is also called advanced-stage or late-stage ovarian cancer. At this stage, cancer has spread far beyond the ovaries or fallopian tubes to other parts of the body. Cancer may be found in organs or locations that are far away from the ovaries.

There are two subcategories of stage 4 ovarian cancer:

• Stage 4A (any T, any N, M1A) — Cancer cells are found in the fluid that surrounds the lungs.
• Stage 4B (any T, any N, M1B) — Cancer is found inside the spleen or liver (not just on the surface), in distant organs such as the lungs or bones, or in lymph nodes outside the abdomen.

How Are Grades and Stages Used?

Oncologists use grading and staging information in several ways. This information helps your doctor estimate your prognosis (outlook), understand how the cancer might progress, and choose the most effective ovarian cancer treatment plan for you.

Lower-grade and earlier-stage tumors are generally less aggressive, may have a better outlook, and are often easier to treat.

Higher-grade or later-stage tumors may be more likely to spread and need a more aggressive treatment plan. They generally have lower survival rates.

However, some ovarian tumors may be treated differently even when they are at the same stage. An oncologist will also take other factors into consideration, such as the ovarian cancer type or certain characteristics of the person who has cancer.

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