Ovarian cancer describes cancer in women that begins in the different cells of the ovaries (they produce eggs), fallopian tubes or peritoneum, which determines the type of ovarian cancer.
Ovarian cancer: learn more
Women have two ovaries, which are reproductive glands that produce eggs for reproduction. The eggs travel from the ovaries through the fallopian tubes into the uterus, where a fertilized egg develops into a fetus.
Recent research in women with ovarian cancer shows that cancer actually starts in the fallopian tubes and spreads to the surface of the ovaries and beyond. In comparison, the ovarian cancer lifetime risk for the women in the general population is less than 2%.
Types of ovarian cancer
Epithelial carcinoma. Makes up 85% to 90% of ovarian/fallopian tube cancers. The main types of epithelial tumors include serous, endometrioid, clear cell, mucinous, mixed tumors and several rare malignancies, including Brenner tumors.
Germ cell malignancies. Develops in the egg-producing cells of the ovaries, typically occurring in women 10 years to 29 years old. Types of germ cell tumors include dysgerminomas, immature teratoma, endodermal sinus tumors (called EST and yolk sac tumors) and embryonal carcinomas.
Sex cord stromal tumors. A rare form of ovarian tumor that develops in the connective tissue cells, called granulosa and theca cells, that hold the ovaries together. Over 90% of these stromal tumors are called granulosa cell tumors; the other types are Sertoli-Leydig cell tumors and steroid cell tumors.
Fallopian tube cancer. We now know that most cancers previously considered ovarian cancer actually began in a fallopian tube.
Causes of ovarian cancer
Research is ongoing, but we still don’t fully understand the exact cause of most ovarian cancers. The recent discovery that ovarian cancer typically starts in cells at the tail ends of the fallopian tubes—not the ovaries—has led to more research into prevention and screening. We have made significant progress in understanding how certain gene mutations can cause normal cells to become cancerous.
Inherited genetic mutations. We know that a small portion of ovarian cancers occur in women with inherited mutations linked to an increased risk of ovarian cancer, including mutations in the BRCA1 and BRCA2 genes.
Acquired genetic changes. Most mutations related to ovarian cancer are not inherited, but occur during a woman’s life. Studies have not linked any single chemical in the environment or in our diets to mutations that cause ovarian cancer—the cause of most acquired mutations remains unknown.
Risk factors in developing ovarian cancer
Even though we don’t know the exact cause of ovarian cancer, we do know that there are several risk factors:
- Aging. Ovarian cancer is rare in women younger than 40. Most ovarian cancers develop after menopause. Half of all ovarian cancers are found in women 63 years of age or older.
- Being overweight or obese. Obesity has been linked to a higher risk of developing many cancers.
- Fertility treatment. In vitro fertilization (IVF) seems to increase the risk. If you are taking fertility drugs, you should discuss the potential risks with your doctor.
- Having a family cancer syndrome. About 5 to 10% of ovarian cancers are a part of family cancer syndromes resulting from inherited changes in certain genes.
- Having a family history of ovarian cancer, breast cancer, or colorectal cancer. A family history of some other types of cancer such as colorectal and breast cancer is linked to an increased risk of ovarian cancer.
- Having had breast cancer. The risk of ovarian cancer after breast cancer is highest in those women with a family history of breast cancer.
- Having your first child after age 35 or never having a full-term pregnancy.
- Hereditary breast and ovarian cancer syndrome. Caused by inherited mutations in the genes BRCA1 and BRCA2, as well as possibly some other genes that have not yet been found.
- Hereditary nonpolyposis colon cancer (HNPCC). Also known as Lynch syndrome.
- Hormone therapy after menopause. Women using estrogens after menopause have an increased risk. The risk seems to be higher in women taking estrogen alone (without progesterone) for many years.
- MUTYH-associated polyposis. This syndrome is caused by mutations in the gene MUTYH.
- Peutz-Jeghers syndrome.
- PTEN tumor hamartoma syndrome. Also known as Cowden disease.