Types of Ovarian Cancer

The majority of ovarian cancers, approximately 85 percent to 90 percent, are epithelial ovarian cancer and are believed to originate from a type of tissue called the epithelium, which covers the ovary surface. Current research in patients with BRCA mutations suggests, however, that ovarian cancer may originate from the cells lining the fallopian tube. This website addresses epithelial ovarian cancers, except when indicated. The serous type of epithelial ovarian cancer is the most common; mucinous, endometroid and clear cell are three other types, and describe different appearance of the malignant tissue under the microscope as well as different behavior of the cancer.

Malignancies of germ cells, which form the eggs every month, are examples of non-epithelial ovarian cancer. They comprise 5 percent to 10 percent of ovarian cancer cases and are usually seen in women less than 25 years old. Most germ cell cancers have a 90 percent survival rate 5 years after diagnosis.

Sex cord and stromal cancers are another non-epithelial ovarian cancer seen in 5 percent to 8 percent of women. These also have approximately a 90 percent survival rate 5 years after diagnosis.