Fertility treatment and risk of breast cancer.

The relationship between fertility treatment and breast cancer was investigated in a multicentric case-control study conducted in Italy on 2569 women with incident, histologically confirmed breast cancer and 2588 control women admitted to hospitals for acute, non-neoplastic, non-hormonal or gynaecological conditions, unrelated to fertility problems. The odds ratio of breast cancer was 1.08 (95% confidence interval 0.8-1.5) in those reporting fertility treatment compared with those who did not receive fertility treatment. Similarly, the odds ratio was 0.60 for women with tubal occlusion, 0.99 for those reporting hormonal imbalances and 1.32 for other/unspecified reasons. There was no consistent pattern of risk according to age at treatment and time since treatment. Women reporting fertility treatment with drug use had an odds ratio of 1.43, while those who did not report drug therapy had an odds ratio of 0.85. None of these odds ratio estimates was significant. Likewise, there was no heterogeneity among strata of parity, menopausal status, education and family history of breast cancer. Thus, our study, while providing reassuring evidence on the relationship between fertility treatment and breast cancer risk, cannot exclude the possibility that the use of specific drugs may be related to breast carcinogenesis.