Benign ovarian cysts and breast cancer risk

Abstract

Benign ovarian cysts have been suggested to influence breast cancer risk. To provide a comprehensive picture of the relation between ovarian cysts and breast cancer, we analyzed the data of 3 case-control studies conducted in northern Italy and the Swiss Canton of Vaud between 1983 and 2001. These studies included 6,315 incident, histologically confirmed breast cancer cases and 6,038 hospital-based controls. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated using unconditional multiple logistic regression models, including terms for sociodemographic, menstrual and reproductive factors. Overall, 4.9% of breast cancer cases and 6.6% of controls reported a history of ovarian cysts, with a multivariate OR of 0.72 (95% CI 0.62-0.85). The inverse association between ovarian cysts and breast cancer was consistent in separate strata of age at menarche, parity, age at menopause status and family history of breast cancer. No meaningful differences were also found across strata of menstrual cycle length, oral contraceptive use, history of oophorectomy and body mass index. Thus, the inverse relation between ovarian cysts and breast cancer risk was not accounted for by earlier menopause, or by any difference in reproductive and menstrual characteristics. Although some hormonal correlates of ovarian cysts may have a role on breast cancer risk, a biological explanation of this inverse association is still unclear. ' 2006 Wiley-Liss, Inc.

Ovarian cysts and breast cancer: results from the Women’s Contraceptive and Reproductive Experiences Study

“…Consistent with recent reports from two other large studies [4,5], we observed significant inverse associations between a reported diagnosis of ovarian cysts and breast cancer. However, in the present study the evidence for an association was stronger in African Americans than in Caucasians.…”

“…An OR of 0.71 (95% CI 0.61-0.81) was observed for a reported diagnosis of ovarian cysts and the result was consistent across study sites and was also consistent Data from the Women's CARE Study are consistent with the two recent pooled analyses in that all the OR estimates were less than 1.00. The results for the African American women are quite similar to the recent pooled analyses [4,5]. Although the OR estimates for ovarian cysts in Caucasians were also less than 1.0 in all subgroups, the effect was not significant or was marginally significant except for the significant OR of 0.85 (95% CI 0.76-0.96) among all Caucasians combined.…”

“…Initial reports were largely null [1][2][3], but two recent studies with larger samples have reported a reduced risk of breast cancer significantly associated with a diagnosis of ovarian cysts [4,5].…”

The Japanese Breast Cancer Society clinical practice guideline for epidemiology and prevention of breast cancer

“…A few reports have suggested an inverse association between benign ovarian cyst and breast cancer risk [51][52][53]. The mechanism is unknown, but there is an evidence of decreased breast cancer risk associated with oophorectomy for ovarian cysts [54,55].…”

The Menstrual Cycle and Risk of Breast Cancer: A Review

“…Benign breast disease is characterized by irregular menstrual cycles and is more common at the end of reproductive life (1). Irregular cycles cause cystic disease in the breasts and ovaries and women with cystic ovarian disease therefore have a lower incidence of breast cancer (30).…”