Ovarian Cancer Stages

Ovarian cancer stages are based on how far the cancer cells have spread, which is determined during surgery. Here’s what you should know.

A diagnosis of ovarian cancer is always scary, but it’s important to know that even women diagnosed with an advanced case may not die from it. Unfortunately, about 75 percent of cases are discovered at stage 3 or 4, when the cancer has spread beyond the pelvis. At stage 4, the most advanced, the five-year relative survival rate is low but not zero, as you’ll see in the chart below.

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To judge ovarian cancer stages, your doctors need to see within your body during surgery to know exactly where the cancer cells have spread.

At ovarian cancer stage 1, the cancer remains mainly within the ovaries. In 1a, the cancer is in one ovary only; in 1b, it is in two ovaries; and in 1c, cancer cells spill out of one or both ovaries, sometimes in the fluid of the pelvis or abdomen.

At stage 2, the cancer spreads from the ovaries within the pelvis. In 2a, it has spread to the fallopian tubes or uterus. In 2b, the cancer has gone further but still remains within the pelvis.

At stage 3, the cancer has spread beyond the pelvis up to the abdomen. In 3a, microscopic cancer cells show up in the lining of the upper abdomen or the lymph nodes in the back of the abdomen. In 3b, a tumor is visible in either area but is less than 2 centimeters. In 3c, the tumor is larger, and cancer cells may be on the surface of the liver or spleen.

At stage 4, it has spread even further. In 4a, cancer cells appear in the fluid around the lungs. In 4b, cancer has metastasized to the lungs, liver, or spleen.

Your treatment plan will depend not only on the stage but also the grade of the cancerous tissue after it is removed and examined under a microscope. Normal tissue is made up of a variety of kinds of cells. If the cancerous tissue also contains cells called differentiated tissue, the grade is lower and the cancer less dangerous.

Ovarian cancer grades run from GX — when it can’t be evaluated — to GB (borderline cancerous), G1 (well-differentiated), G2 (moderately differentiated, with more abnormal than normal cells), G3, and G4 (still more abnormal cells).

Survival rates are calculated based on statistics in the SEER database, maintained by the National Cancer Institute (NCI). This system recognizes three categories rather than four stages. It also matters what kind of ovarian cancer you have.

For example, people with epithelial ovarian cancer diagnosed at stage 1 are 92 percent as likely as people without that cancer to live for at least 5 years after diagnosis. This is a 5-year relative survival rate of 92 percent.

The rates below apply to invasive, epithelial ovarian cancer, the most dangerous kind; other types of cancer have higher survival rates.

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