Ovarian Cancer, malignancy in one or both ovaries, the two almond-sized glands on either side of a female’s uterus. Ovaries produce eggs and release hormones that help regulate menstruation and pregnancy. The American Cancer Society estimates that 23,100 new cases of ovarian cancer are diagnosed annually in the United States. Each year an estimated 14,000 women die from the disease. In Canada, about 2,500 cases of ovarian cancer are diagnosed and more than 1,500 women die from the disease each year. Ovarian cancer is the deadliest cancer of the female reproductive system.
Symptoms Ovarian Cancer
There is no effective way to detect ovarian cancer in its early stages. The disease seldom produces symptoms until it begins to spread. At that point, a woman may experience any of a variety of symptoms that may also be attributed to other causes. Such symptoms include an enlarged abdomen, persistent abdominal discomfort, indigestion, nausea or vomiting, weight loss, diarrhea or constipation, and bleeding that is not part of a normal menstrual period.
If a physician suspects an ovarian tumor, ultrasound may be used to create a picture of the organ from a pattern of sound wave echoes—tumors and healthy tissues produce different echoes. In addition, a blood sample may be tested for the presence of CA-125, a tumor marker (biochemical substance or genetic change identified in a lab) that is sometimes produced by ovarian cancer cells. Because CA-125 may also be present in women who have benign ovarian conditions, this test does not provide a definitive diagnosis. Final diagnosis of ovarian cancer depends on a biopsy, in which a sample of tumor tissue is removed during a surgical operation and then examined under a microscope.
CYSTS AND TUMORS
The excessive growth of cells creates a mass of tissue called a tumor. About 80 percent of ovarian tumors are benign, or noncancerous, and the cells do not spread to nearby tissues or to other parts of the body. Many women, even in their 20s, develop benign fluid-filled sacs called ovarian cysts. Cysts sometimes disappear without treatment; in other cases, they must be removed surgically.
Malignant tumors are cancerous and can spread to other tissues through the circulatory system in a process called metastasis. Although ovarian cancer may metastasize anywhere in the body, it commonly spreads to nearby organs like the stomach and intestines.
RISK FACTORS FOR OVARIAN CANCER
On average, a woman has a 1.4 percent chance of being diagnosed with ovarian cancer in her lifetime. Women with a close female relative (a mother, sister, or daughter) who has ovarian cancer have a 7 percent chance of developing the disease. Having two close relatives with the disease increases the risk to 50 percent. A woman who has a mutated version of a gene called BRCA1 or a gene called BRCA2 has a significantly increased risk for developing both ovarian and breast cancer.
Women who have given birth are less likely to develop ovarian cancer than women who have not, and women who have had several pregnancies have a lower risk than women who have had only one child. Other factors that appear to reduce ovarian cancer risk include the use of birth control pills, breast-feeding, undergoing a hysterectomy (even if the ovaries are not removed), and tubal sterilization, or female sterilization.
Studies of Japanese women who were exposed to atomic bomb radiation during World War II (1939-1945) revealed almost twice the expected number of ovarian cancer cases. Other research has linked ovarian cancer to dietary fat intake. One study found that for every 10 g (about 0.35 oz) of saturated fat a woman consumes in an average day, her risk of developing ovarian cancer increases by 20 percent, while every 10 g of vegetable fiber consumed per day lowers her risk by 37 percent. Risk of ovarian cancer also increases with age—incidence is highest among women 60 years old and older.
Ovarian cancer treatment depends on the stage of the disease, the woman’s age, and her general health. The primary treatment for early stage ovarian cancer is surgery to remove one or both ovaries, and often the uterus and fallopian tubes as well. In advanced stages, a combination of surgery and chemotherapy using anticancer drugs such as taxol and topotecan is common. The drugs are usually injected or taken orally.
A potentially powerful treatment for the future is the use of bone marrow transplants. Several institutions are testing a chemotherapy for patients with newly diagnosed ovarian cancer that uses high doses of taxol and another anticancer agent, carboplatin, administered at two-week intervals along with stem cells from the patient. Stem cells are primitive cells in the bone marrow that multiply and develop into different types of blood cells. This experimental treatment carries a good deal of risk, however, because stem cells are withdrawn from the patient’s own marrow prior to chemotherapy, leaving her without her normal supply of blood cells and vulnerable to infection.
According to the American Cancer Society, 78 percent of women diagnosed with ovarian cancer survive for at least one year after diagnosis. The five-year relative survival rate falls to 50 percent. The outlook is much more promising if the cancer is diagnosed and treated while still localized. In these cases, the five-year relative survival rate is 95 percent. Only about 25 percent of all cases are detected at this stage, however.