Researchers have identified several factors, including breastfeeding and oral contraceptives, that may decrease the risk of BRCA-associated ovarian cancer.
Researchers have identified several factors that may decrease the risk for ovarian cancer among women with BRCA1 and BRCA2 mutations, results of a study published in the International Journal of Cancer indicate. Among the factors identified were prolonged use of oral contraceptives and breastfeeding for 12 months or more.
Joanne Kotsopoulos, PhD, of Women’s College Research Institute, Toronto, Canada, and colleagues conducted a study to evaluate the lifetime number of ovulatory cycles, and other contributing components, in the context of BRCA-associated ovarian cancer.
The study included 1,329 BRCA mutation carriers diagnosed with invasive epithelial ovarian cancer and 5,267 matched control patients who never had ovarian cancer. The women completed baseline questionnaires about their personal and family histories of cancer and reproductive details during clinic appointments or at their homes at a later date.
The researchers found no significant relationship between parity and risk for ovarian cancer among women with a BRCA1 mutation; however, an inverse association was found with increasing number of live births (odds ratio [OR] per birth = 0.87; 95% CI, 0.79-0.96). In addition, among those women who had given birth, age at last birth was inversely associated with risk (OR = 0.92; 95% CI, 0.84-1.00).
Data indicated breastfeeding for 12 months of longer conferred a 38% reduced risk for ovarian cancer among women with BRCA1 mutations (OR = 0.62; 95% CI, 0.48-0.79) and a 50% reduced risk among women with BRCA2 mutations (95% CI, 0.29-0.84).
Among women with BRCA1 mutations, oral contraceptive use was linked with a 40% reduction in risk for ovarian cancer (OR = 0.60; 95% CI, 0.50-0.71). Women who had used oral contraceptives for 5 years or longer had a 50% decreased risk. Oral contraceptive use was also found to reduce risk among women with BRCA2 mutations (OR = 0.63; 95% CI, 0.44-0.92), with those women taking them for 3 years or longer achieving the most benefit (OR = 0.42; 95% CI, 0.22-0.83).
“With respect to oral contraceptive use for the primary prevention of ovarian cancer, BRCA2 mutation carriers should be advised to use for at least 3 years; however, given the increased risk of breast cancer associated with oral contraceptive use prior to age 25 among BRCA1 mutation carriers, women with a BRCA1 mutation should be advised to initiate use after the age of 25 and continue for 5 years,” the researchers wrote.
The researchers also found a link between increased age at menopause and an increased risk for ovarian cancer in women with BRCA1 mutations. Specifically, women who achieved menopause at age 50 had a 75% increased risk for cancer than did those who achieved menopause prior to age 42.
In women with BRCA2 mutations, no link between parity or age at menopause and ovarian cancer risk was found.