Rocky Mountain Cancer Centers

Tumors there are named for the kinds of cells the tumor started from and whether the tumor is benign or cancerous.

• Most ovarian tumors are epithelial cell tumors.
• Ovarian cancer is the ninth most common cancer among women (not counting skin cancer). In 2011, the American Cancer Society estimates that 21,900 women in the U.S. will be diagnosed with ovarian cancer.
• A woman’s risk of getting invasive ovarian cancer in her lifetime is about 1 in 71.

Abnormal growths can develop in the ovaries. If the growths, or tumors, are benign (noncancerous), they will not spread beyond the ovary and usually do not present a serious problem. If the tumors are malignant (cancerous), they can spread to other parts of the body (metastasize) and can become life threatening.

Ovarian cancers can grow from any of the cells that make up the ovary. There are three main forms of ovarian cancer: epithelial (cells that line the ovary’s surfaces), stromal (connective tissue) and germ cell (cells that produce eggs). A sub-type of epithelial cancers, called “borderline” ovarian tumors also occurs, but is uncommon. If the tumors are malignant (cancerous), they can metastasize and become life threatening.

Epithelial ovarian carcinomas (EOC) begin on the surface of the ovary. EOC is the most common type of ovarian cancer, and accounts for 90 percent of all ovarian cancers. Epithelial tumors most often occur in women around the age of 60, but they can develop anytime between the ages of 20 and 90 years. Based upon how they look under the microscope, there are five forms of EOCs. These forms are called serous, mucinous, endometrioid, clear cell, and undifferentiated. Serous is the most common type. Mucinous is a less favorable type, and clear cell is the most serious, as this cell type seems to be especially aggressive.

Borderline ovarian tumors (Low Malignant Potential) are on the surface of the ovary. When examined closely by a pathologist they are not clearly cancerous. These “carcinomas of low malignant potential” (LMP) account for approximately 15 percent of all epithelial ovarian carcinomas. Tumors of low malignant potential usually occur in women less than 40 years and have a favorable prognosis regardless of stage. These tumors are not very aggressive, are usually discovered early, and seldom spread to other parts of the body. (They are not invasive.) Even if the tumor is advanced and has metastasized, 80 to 90 percent of the patients will survive.

Stromal tumors begin either in the connective tissue that holds the ovary together or in the cells that make estrogen and progesterone. Most occur in women over the age of 50, although they can also appear in younger women. Stromal tumors usually do not spread to other parts of the body, and thus patients usually have a good prognosis. However, if they do spread, they can be very difficult to treat. Stromal tumors are relatively uncommon and account for 6 to 10 percent of all ovarian cancers. The three types of stromal tumors are granulosa cell tumors, granulosa-theca tumors, and Sertoli-Leydig cell tumors.

Germ cell tumors develop in the cells that produce eggs. They most often occur in teenagers and young women. They tend to be very sensitive to chemotherapy, and about 90 percent of patients with germ cell tumors are cured. Germ cell tumors account for 3 percent of all ovarian cancers. The four types of germ cell tumors are dysgerminomas, endodermal sinus tumors, choriocarcinomas and immature teratomas.