Ovarian and Uterine Clinical Resource Area - Disease Overview

Ovarian Cancer

Normal Anatomy and Physiology
The internal genitalia of the female reproductive system includes the uterus, two ovaries, two fallopian tubes, the urethra, the pubic bone, and the rectum. The uterus (womb) contains an inner lining called the endometrium (which builds ups and sheds monthly in response to hormonal stimulation). The lower portion of the uterus is called the cervix, which contains a small opening called the os. Menstrual blood flows through the os into the vagina during menstruation. Semen travels through the os into the uterus and the fallopian tubes following ejaculation during sexual intercourse. The cervical os dilates (opens) during childbirth.

The ovaries complete two functions: the production of mature ova (eggs), and the production of the female sex hormones estrogen and progesterone. At birth, the woman's ovaries contain all of the eggs that she will ever have. There are nearly 400,000 ova. Because women have on average about 500 periods, there are far more eggs available than actually needed. The mature egg journeys from the ovary to the fallopian tubes, then to the uterus.  Eggs that are not fertilized leave the body during menstruation.  

Epidemiology
Ovarian cancer is the eighth most common cancer among women, excluding non-melanoma skin cancers. The American Cancer Society estimates that about 22,430 new cases of ovarian cancer will be diagnosed in the United States during 2007. Ovarian cancer accounts for about 3% of all cancers in women.

A woman's risk of getting ovarian cancer during her lifetime is 1.5% or about 1 in 67. Her lifetime chance of dying from ovarian cancer is 1.05% or 1 in 95. The risk of developing and dying from ovarian cancer is higher for white women than black women.

This is a cancer that mainly develops in older women. Around two-thirds of women are 55 or older. It is slightly more common in white women that African-American women.

The ovarian cancer incidence rate has decreased by about 0.7% per year since 1985. Ovarian cancer ranks fifth in cancer deaths among women, accounting for more deaths than any other cancer of the female reproductive system. It is estimated that there will be about 15,280 deaths from ovarian cancer in the United States during 2007.

Risk Factors
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.

There is a much higher incidence of ovarian cancer in industrialized countries. Some researchers have implicated talcum powder, which until recently contained asbestos, as a possible cause. Ovarian cancer can occur in any age group, but is most common in postmenopausal women. Not ovulating-by having children, breastfeeding, using birth control pills or having a condition that interferes with ovulation such as polycystic ovaries-has been shown to offer protection against developing cancer. There may also be a genetic predisposition to this cancer. There are rare families in which several members of the same or different generation develop ovarian cancer. This is known as hereditary ovarian cancer syndrome. Women with hereditary ovarian cancer syndrome are also at significant risk for the development of breast cancer, uterine cancer, and colon cancer. These individuals are often positive for the BRCA-1 or BRCA-2 gene, which can be tested for. It generally affects women in their mid-forties. There may be up to a 50 percent risk of developing ovarian cancer in their lifetime. It can also be inherited through the male side of the family. This syndrome occurs in less than 3 percent of all women who have a positive family history of ovarian cancer. Approximately 7 percent of all women with ovarian cancer do not seem to have a genetic disposition but have a positive family history. Ninety percent of these women have only one other family member with ovarian cancer.

Suggested management in women with a family history for ovarian cancer is as follows: Removal of both ovaries and sometimes the uterus after childbearing or very close follow-up with serum CA-125 and pelvic ultrasound for those women who have hereditary ovarian cancer syndrome. If there is a family history of only one relative with ovarian cancer, prophylactic removal of the ovaries is not recommended. In women who are BRCA-1 or BRCA-2 negative and who have 2-3 close relatives with ovarian cancer, prophylactic removal of the ovaries is generally recommended by most gyn oncologists and geneticists

Deterrence/Prevention:

• Pregnancy and the use of oral contraceptives significantly decrease the risk of ovarian cancer.
• Prophylactic bilateral salpingo-oophorectomy is indicated in high-risk women, particularly women with a genetic predisposition for ovarian cancer (ie, BRCA carriers). Surgical prophylaxis decreases the risk by at least 90%. Not all cases of ovarian cancer are prevented as women are still at risk for developing primary peritoneal carcinomas.
• No approved screening method is available for ovarian cancer. However, the use of transvaginal ultrasonography and CA-125 tumor marker is recommended in high-risk women.