Basic Information
Among women in the United States, ovarian cancer is the eighth most common cancer and the fifth leading cause of cancer death, after lung and bronchus, breast, colorectal, and pancreatic cancers.* Ovarian cancer causes more deaths than any other cancer of the female reproductive system. Mortality and incidence rates are higher for white women than for any other racial or ethnic group. In the United States, approximately $2.2 billion (in 2004 dollars) is spent each year on the treatment of ovarian cancer.
*Incidence counts cover approximately 98% of the U.S. population. Death counts cover 100% of the U.S. population. Use caution in comparing incidence and death counts.
Risk Factors
Although most cases of ovarian cancer occur in women aged 50 years or older, the disease can occur in younger women. The most common form of ovarian cancer-epithelial-usually is diagnosed in women aged 40 years or older. Risk for all forms of the disease begins to increase as a woman gets older.
A woman's chance of having ovarian cancer increases if one or more of her close relatives (i.e., mother, daughter, or sister) has had the disease. In some cases, women may inherit genes that substantially increase the risk of developing ovarian cancer. Women with a history of breast, endometrial, or colon cancer also have a greater chance of developing ovarian cancer than do women who have not had these cancers.
Reducing Risk
Researchers have identified several factors that may decrease a woman's risk of developing ovarian cancer, including childbearing and the use of oral contraceptives. Although reproductive, demographic, and lifestyle factors affect risk of developing ovarian cancer, the single greatest risk factor for ovarian cancer is having a family history of the disease.
Screening
CDC and other federal agencies follow the ovarian cancer screening recommendations set forth by the U.S. Preventive Services Task Force (USPSTF), which is supported by the Agency for Healthcare Research and Quality (AHRQ). USPSTF recommends against routine screening for ovarian cancer. There is no evidence that any screening test-CA-125, ultrasound, or pelvic examination-reduces deaths from ovarian cancer.
The USPSTF, first convened by the U.S. Public Health Service in 1984, and since 1998 sponsored by the AHRQ, is the leading independent panel of private-sector experts in prevention and primary care. The USPSTF conducts rigorous, impartial assessments of the scientific evidence for the effectiveness of a broad range of clinical preventive services, including screening, counseling, and preventive medications. Its recommendations are considered the "gold standard" for clinical preventive services.
The mission of the USPSTF is to evaluate the benefits of individual services based on age, gender, and risk factors for disease; make recommendations about which preventive services should be incorporated routinely into primary medical care and for which populations; and identify a research agenda for clinical preventive care.
The Ovaries
The ovaries are part of a woman's reproductive system. They are in the pelvis. Each ovary is about the size of an almond.
The ovaries make the female hormones - estrogen and progesterone. They also release eggs. An egg travels from an ovary through a fallopian tube to the womb (uterus).
When a woman goes through her "change of life" (menopause), her ovaries stop releasing eggs and make far lower levels of hormones.
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| This picture is of the ovaries and nearby organs. |
Understanding Cancer
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.
Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.
Tumors can be benign or malignant:
Benign and Malignant Cysts
An ovarian cyst may be found on the surface of an ovary or inside it. A cyst contains fluid. Sometimes it contains solid tissue too. Most ovarian cysts are benign (not cancer).
Most ovarian cysts go away with time. Sometimes, a doctor will find a cyst that does not go away or that gets larger. The doctor may order tests to make sure that the cyst is not cancer.
Ovarian Cancer
Ovarian cancer can invade, shed, or spread to other organs:
Invade: A malignant ovarian tumor can grow and invade organs next to the ovaries, such as the fallopian tubes and uterus.
Shed: Cancer cells can shed (break off) from the main ovarian tumor. Shedding into the abdomen may lead to new tumors forming on the surface of nearby organs and tissues. The doctor may call these seeds or implants.
Spread: Cancer cells can spread through the lymphatic system to lymph nodes in the pelvis, abdomen, and chest. Cancer cells may also spread through the bloodstream to organs such as the liver and lungs.
When cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the original tumor. For example, if ovarian cancer spreads to the liver, the cancer cells in the liver are actually ovarian cancer cells. The disease is metastatic ovarian cancer, not liver cancer. For that reason, it is treated as ovarian cancer, not liver cancer. Doctors call the new tumor "distant" or metastatic disease.
Risk Factors
Doctors cannot always explain why one woman develops ovarian cancer and another does not. However, we do know that women with certain risk factors may be more likely than others to develop ovarian cancer. A risk factor is something that may increase the chance of developing a disease.
Studies have found the following risk factors for ovarian cancer:
Family history of cancer: Women who have a mother, daughter, or sister with ovarian cancer have an increased risk of the disease. Also, women with a family history of cancer of the breast, uterus, colon, or rectum may also have an increased risk of ovarian cancer.
If several women in a family have ovarian or breast cancer, especially at a young age, this is considered a strong family history. If you have a strong family history of ovarian or breast cancer, you may wish to talk to a genetic counselor. The counselor may suggest genetic testing for you and the women in your family. Genetic tests can sometimes show the presence of specific gene changes that increase the risk of ovarian cancer.
Personal history of cancer: Women who have had cancer of the breast, uterus, colon, or rectum have a higher risk of ovarian cancer.
Age over 55: Most women are over age 55 when diagnosed with ovarian cancer.
Never pregnant: Older women who have never been pregnant have an increased risk of ovarian cancer.
Menopausal hormone therapy: Some studies have suggested that women who take estrogen by itself (estrogen without progesterone) for 10 or more years may have an increased risk of ovarian cancer.
Scientists have also studied whether taking certain fertility drugs, using talcum powder, or being obese are risk factors. It is not clear whether these are risk factors, but if they are, they are not strong risk factors.
Having a risk factor does not mean that a woman will get ovarian cancer. Most women who have risk factors do not get ovarian cancer. On the other hand, women who do get the disease often have no known risk factors, except for growing older. Women who think they may be at risk of ovarian cancer should talk with their doctor.
 Epithelial ovarian cancer is the leading cause of death from gynecologic cancer in the U.S. In 2004, 25,580 new cases were diagnosed and 16,090 women died from this disease. The incidence of this cancer increases with each decade and peaks for women in their eighties. Each pregnancy reduces the ovarian cancer risk by about 10% and breast feeding and tubal ligation also appear to reduce the risk.
Most patients with ovarian cancer are first diagnosed when the disease has already spread beyond the true pelvis. The occurrence of abdominal pain, bloating, and urinary symptoms usually indicates advanced disease. Localized ovarian cancer is generally asyptomatic (has no symptoms). Patients with early ovarian cancers (stages I and II) are commonly curable with conventional therapy. Laparotomy is often the primary procedure used to establish the diagnosis. (A laparotomy is a surgical incision into the abdominal cavity.)
Staging and Prognosis
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| Stage | Description | Frequency | 5-year Survival | | I | Cancer confined to the ovary or ovaries | 23% | 90% | | II | Cancer confined to the true pelvis | 13% | 70% | | III | Cancer spread into but confined to the abdomen | 47% | 15-20% | | IV | Cancer spread outside the pelvis and abdomen | 16% | 1-5% |
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