Ovarian cancer is the fifth most common cancer in women but accounts for the most deaths of all female reproductive cancers, according to the National Institutes of Health. This cancer arises in either of the two ovaries, which are the female reproductive organs that produce eggs.
Risk factors are possible causative agents implicated in the development of ovarian cancer.
Age
Ovarian cancer affects all ages of women, but according to the American Society of Clinical Oncology, almost 70 percent of women with this cancer are over 55 years of age. The American Cancer Society adds that ovarian cancers are rare in women under 40 years of age.
Reproductive History
According to the ACS, women who have given birth appear to have lower risks than who have not borne children, and the risk is lower with each subsequent pregnancy. The use of oral contraceptive pills appears to reduce the risks of ovarian cancer.
The ASCO adds that early start of menstruation, before 12 years of age, and/or late menopause, after 50 years of age, appear to confer higher risks.
Obesity
MayoClinic.com reports that obesity, a body mass index of at least 30, increases the risk of developing ovarian cancer. Though the ACS does not fully support this view, the ACS reports that there is a higher death rate from ovarian cancer among the obese, which increases with the degree of obesity.
Infertility
The risks of developing ovarian cancer appear to be higher in women who have trouble with conception. According to the ACS, this could be linked to the fact that they have not had children, used fertility drugs like Clomid for over a year without success, or have not used oral contraceptive pills--which appear to offer some protection.
Hormone Replacement Therapy
Women who use estrogen-only hormone replacement therapy after menopause are at higher risk for ovarian cancer, particularly if they take these pills for more than five years, according to MayoClinic.com.
Family History
According to the ACS, having a first-degree relative--mother, daughter or sister--with ovarian cancer increases the risk in other family members.
Gene mutations, which also run in families, increase the risks for ovarian cancer. One such series of mutations seen in people with breast cancer and colorectal cancer is BRCA1 and BRCA2. The presence of these genes, according to MayoClinic.com, is the strongest risk factor for the development of ovarian cancer. Thus, a family history of breast cancer and colorectal cancer also increases the risk for ovarian cancer.
Other Risk Factors
Male hormones, androgens, used to treat some gynecological conditions such as endometriosis, have been found to increase the risks for ovarian cancer, according to the ACS
The ACS adds that bilateral tubal ligation appears to reduce the risks of ovarian cancer by two thirds while a hysterectomy apparently reduces the risks by one third.
According to the ASCO, homosexual and bisexual women have a higher risk than heterosexuals. This may be linked to the fact that lesbians are less likely to have children or use oral contraceptive pills, both of which appear protective.
