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Breast and Ovarian Cancer
  What Is Ovarian Cancer?
what is ovarian cancer

By Kathleen Fergus, MS, CGC and Jill Simonsen

Reviewed by Beth Crawford, MS, CGC
Last updated September 5, 2011





Ovarian cancer affects far fewer women than many other cancers, however, the difficulty in detecting the cancer in its early stages makes it particularly troublesome. For this reason it is especially important for women to know if they are at high risk so they can go through more rigorous screening than is available to the general public.

 
 
 

Who Gets Ovarian Cancer?

what is ovarian cancer
Half of all ovarian cancers are found in women over the age of 65.
what is ovarian cancer
The American Cancer Society estimates that in the US approximately 1.4 percent (or 1 in 70) women will develop ovarian cancer over the course of their lives. This translates to approximately 25,000 women developing ovarian cancer and 14,000 women dying as a result of their disease in the year 2000, making it the fifth most common type of cancer as well as the fifth most common reason for cancer fatality for woman in the United States.

As is the case with most cancers, the risk of developing ovarian cancer increases with age, with the highest rates occurring among women who are more than 60 years old. The second most important risk factor is being of European or North American descent.

It's important to keep in mind that these statistics apply to the general population. There are a number of factors — both environmental and genetic — that increase or decrease a woman's risk for ovarian cancer.

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Where Does Ovarian Cancer Begin?

The ovaries are a pair of almond-sized organs that are located on either side of a woman's uterus. They produce eggs as well as the female hormones estrogen and progesterone, which regulate the menstrual cycle and pregnancy. The ovaries themselves are composed of layers of cells: the inner, or germ, layer (which produces eggs) and the outer covering, which is referred to as the epithelial layer.

In all cancers, cells in the human body change and experience out-of-control growth. In the case of ovarian cancer, this can occur in the epithelial layer, the germ layer, or the supportive tissues that surround the ovaries. By far the most common type of ovarian tumors are those that begin in the epithelial layer. Accounting for approximately 90 percent of all ovarian cancers, this type of malignancy is called ovarian epithelial cancer.

Ovarian cancers spread to other organs in a couple of ways. Ovarian cancer cells can break away from the ovary and spread to other tissues and organs in a process called shedding. In this situation, new tumors tend to form on the the large membrane that lines the abdomen (peritoneum) and on the the thin muscle that separates the chest from the abdomen (diaphragm).

Ovarian cancer cells can also enter the bloodstream or lymphatic system (the tissues and organs that produce and store cells that fight infection and disease), where they can travel to other parts of the body and form new tumors.

what is ovarian cancertop

 

Signs and Symptoms

Ovarian cancer often does not produce any symptoms until after the cancer has spread to other organs. For example, as the malignant cells spread, fluid builds up in the peritoneum, and this is what causes the abdominal swelling and bloating that can be one sign of ovarian cancer. When ovarian cancer does produce symptoms, they are often nonspecific and could be caused by more common and less dangerous disorders. Because early-stage ovarian cancer rarely produces symptoms, 75 percent of ovarian cancers are not diagnosed until after the cancer has spread to other organs. (For news about detecting symptoms of ovarian cancer, see related news below. )

Ovarian Cancer Symptoms

  • Abdominal swelling and pain
  • Bloating
  • Indigestion, gas, or nausea
  • A feeling of fullness in the pelvis
  • Unexplained weight loss or gain
  • Abnormal vaginal bleeding (rare)
  • Back pain
  • Fatigue
  • Constipation or diarrhea

what is ovarian cancertop

 

Factors That Increase Risk

Ovarian cancer is believed to be caused by a combination of genetic and environmental factors. Keep in mind, however, that you may have risk factors and never develop ovarian cancer, while other people who get the disease do not have any of the following risk factors.

Genetic factors. Scientists believe that approximately ten percent of ovarian epithelial cancer can be attributed to an inherited susceptibility caused by mutations in two genes called BRCA1 and BRCA2. These two genes also confer an increased risk of other cancers (the primary example being breast cancer) if mutated. The genetic cancer syndrome hereditary nonpolyposis colorectal cancer, or HNPCC, also increase a woman's risk of developing ovarian cancer. However, less than two percent of ovarian cancers are thought to be attributed to HNPCC, which is also characterized by an increased risk for colon, endometrial, and stomach cancer.

Nongenetic factors. Other factors that may increase your risk for ovarian cancer include a high-fat diet, never having given birth to a child, and never having breast-fed a child.

Screening

what is ovarian cancer
There is no single, effective screening test for ovarian cancer.
what is ovarian cancer
Most cancers are highly treatable if they are identified before they metastasize. However, only about 25 percent of ovarian cancers are detected this early. One reason is that the ovaries are relatively inaccessible and so are harder to screen than are the breasts. In addition, there is no single, effective screening test. Even when tests are combined to improve their performance they still yield a high number of false positive and false negative results. This means that they may suggest a cancer when none exists, or they may miss a cancer that is present. The bottom line is that there is no recommended screening test for women who do not appear to be at increased risk for the disease.

For women who are at high risk for ovarian cancer, such as women with a strong family history of the disease, some combination of techniques — including blood tests, physical examination of the ovaries, and ultrasound scans — may be recommended. However, there's still much disagreement regarding the usefulness of these methods even for high-risk women.

Prevention

For women who are not at high risk of developing ovarian cancer, the best step they can take to prevent the disease is to reduce the environmental risk factors that are under their control — for example, by taking oral contraceptives or following a low-fat diet.

Women whose personal medical history or family medical history puts them at increased risk for ovarian cancer may want to consider removal of the ovaries (prophylactic oophorectomy). Although there are data showing that this procedure is effective in reducing the risk of ovarian cancer, there are reports of women who have developed cancer of the peritoneum after a prophylactic oophorectomy — theoretically from ovarian cells that remained after surgery. With this type of surgery, there are obviously many issues to be weighed such as the resulting infertility. Any woman considering this option should discuss the benefits, risks, and limitations with her physician before making a decision.

 

what is ovarian cancertop
More on Chemoprevention for Ovarian Cancer (Coming Soon)

 

Treatment

Ovarian cancer treatment depends on the type of tumor as well as how far the cancer has spread at diagnosis. In addition, an individual's age, menopausal status, and overall health all play a role in determining the best treatment option.

In most cases surgical treatment — usually the removal of one or both ovaries, the uterus, and the fallopian tubes — is the first step. Then, depending on how far the cancer has spread, chemotherapy and/or radiation may be prescribed.

what is ovarian cancertop

Related News
In order to view these articles you will need to have a MyGeneticHealth account. If you are not already a member, selecting the article will automatically take you to a page where you can sign up.
Estrogen therapy linked to ovarian cancer risk
Aspirin use may be associated with reduced risk of ovarian cancer
what is ovarian cancerWomen, doctors miss signs of ovarian cancer

Resources

To learn more about treatment options for ovarian [or breast] cancer, we recommend the National Institutes of Health Cancer Web site or the National Cancer Institute of Canada.

 

References


Baker, T. R. and M. S. Piver (1994). Etiology, biology, and epidemiology of ovarian cancer. Semin Surg Oncol 10(4): 242-8.

Daly, M. and G. I. Obrams (1998). Epidemiology and risk assessment for ovarian cancer. Semin Oncol 25(3): 255-64.

Data, A. C. S. (2000). Data from the American Cancer Society website.

Eisen, A. et al. (2000). Prophylactic surgery in women with a hereditary predisposition to breast and ovarian cancer. J Clin Oncol 18(9): 1980-95.

Finazzo, M. S. et al. (1988). Previous pelvic surgery in patients with ovarian cancer. South Med J 81(12): 1518-20.

Fitch, M. I. et al. (1999). Gynecologists' perspectives regarding ovarian cancer. Cancer Prev Control 3(1): 68-76.

Gayther, S. A., et al. (1997). Variation of risks of breast and ovarian cancer associated with different germline mutations of the BRCA2 gene. Nat Genet 15(1): 103-5.

Karlan, B. Y. and L. D. Platt (1995). Ovarian cancer screening. The role of ultrasound in early detection. Cancer 76(10 Suppl): 2011-5.

Ozools R.F. et al (1997). Epithelial Ovarian Cancer. Philadelphia, Lippincott-Raven.

Rosenthal, A. N. and I. J. Jacobs (1998). The role of CA 125 in screening for ovarian cancer. Int J Biol Markers 13(4): 216-20.

Rozario, D. et al. (1997). Is incidental prophylactic oophorectomy an acceptable means to reduce the incidence of ovarian cancer? Am J Surg 173(6): 495-8.

Stratton, J. F. et al. (1997). Contribution of BRCA1 mutations to ovarian cancer. N Engl J Med 336(16): 1125-30.

Struewing, J. P. et al. (1995). Prophylactic oophorectomy in inherited breast/ovarian cancer families. J Natl Cancer Inst Monogr 17: 33-5.

Zurawski, V. R. et al. (1988). Elevated serum CA 125 levels prior to diagnosis of ovarian neoplasia: relevance for early detection of ovarian cancer. Int J Cancer 42(5): 677-80.

 

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