Certain factors may increase your risk of ovarian cancer. Having one or more of these risk factors doesn't mean that you're sure to develop ovarian cancer, but your risk may be higher than that of the average woman. These risk factors include:
Inherited gene mutations. While the vast majority of women who develop ovarian cancer don't have an inherited gene mutation, the most significant risk factor for ovarian cancer is having an inherited mutation in one of two genes called breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2). These genes were originally identified in families with multiple cases of breast cancer, which is how they got their names, but people with these mutations also have a significantly increased risk of ovarian cancer.
Women with the BRCA1 mutation have a 35 to 70 percent higher risk of ovarian cancer than do women without this mutation, and for women with a BRCA2 mutation, the risk is between 10 and 30 percent higher. For most women, the overall lifetime risk is about 1.5 percent, according to the ACS. You're at particularly high risk of carrying these types of mutations if you're of Ashkenazi Jewish descent.
Another known genetic link involves an inherited syndrome called hereditary nonpolyposis colorectal cancer (HNPCC). Women in HNPCC families are at increased risk of cancers of the uterine lining (endometrium), colon, ovary and stomach. Risk of ovarian cancer associated with HNPCC is lower than is that of ovarian cancer associated with BRCA mutations.
- Family history. Sometimes, ovarian cancer occurs in more than one family member but isn't the result of any known inherited gene alteration. Having a family history of ovarian cancer increases your risk of the disease by 10 to 15 percent, according to the ACS.
- A history of breast cancer. If you've been diagnosed with breast cancer, your risk of ovarian cancer also is elevated.
- Age. Ovarian cancer most often develops after menopause. Your risk of ovarian cancer increases with age through your late 70s. Although most cases of ovarian cancer are diagnosed in postmenopausal women, the disease also occurs in premenopausal women.
- Childbearing status. Women who have had at least one pregnancy appear to have a lower risk of developing ovarian cancer. Similarly, the use of oral contraceptives appears to offer some protection against ovarian cancer.
- Infertility. If you've had trouble conceiving, you may be at increased risk. Although the link is poorly understood, studies indicate that infertility increases the risk of ovarian cancer, even without use of fertility drugs. Some research has also suggested that taking fertility drugs, such as clomiphene (Clomid), for more than one year may increase your risk of ovarian cancer, but it's not clear whether the increased risk actually comes from the drug or from the infertility.
- Hormone replacement therapy (HRT). Findings about the possible link between postmenopausal use of the hormones estrogen and progestin and risk of ovarian cancer have been inconsistent. However, a recent analysis of numerous studies, published in the journal Gynecologic Oncology, confirmed an association between HRT and ovarian cancer, particularly for those who took estrogen only. The risk appears to be highest among women who took HRT for more than five years.
- Obesity. Women who are obese have a greater risk of ovarian cancer. Obesity may also be linked to more-aggressive ovarian cancers, which can result in a shorter time to disease relapse and a decrease in the overall survival rate.
- Male hormones. The medication danazol, a male hormone (androgen), is used to treat endometriosis and has been linked to an increased risk of ovarian cancer. More study is needed to further define this association.
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Source: Mayo Clinic Online (http://www.mayoclinic.com/health/ovarian-cancer/DS00293)