Bisphosphonate use after estrogen receptor–positive breast cancer and risk of contralateral breast cancer
Menée sur des patientes ayant eu entre 40 et 79 ans un cancer primitif invasif du sein ER+, cette étude (351 cas et 662 témoins) évalue l'association entre l'utilisation de bisphosphonates et le risque de cancer du sein controlatéral
Background A growing body of evidence suggests that nitrogenous bisphosphonates may reduce the risk of developing a first breast cancer and may prevent metastases among breast cancer survivors. However, their impact on risk of second primary contralateral breast cancer is uncertain.Methods Within a nested case–control study among women diagnosed with a first primary estrogen receptor–positive invasive breast cancer at ages 40–79 years, we assessed the association between post-diagnostic bisphosphonate use and risk of second primary contralateral breast cancer. We used multivariable-adjusted conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) comparing 351 contralateral breast cancer case subjects with 662 control subjects (ie, breast cancer patients not diagnosed with contralateral breast cancer) who were incidence density–matched on county; race/ethnicity; and age at, year of, and stage at first breast cancer diagnosis. We performed sensitivity analyses with respect to bisphosphonate type and confounding by indication. All statistical tests were two-sided.Results Current use of any nitrogenous bisphosphonate and use specifically of alendronate were both associated with reduced risks of contralateral breast cancer compared with never use (OR = 0.41, 95% CI = 0.20 to 0.84 and OR = 0.39, 95% CI = 0.18 to 0.88, respectively). The risk of contralateral breast cancer further declined with longer durations of bisphosphonate use among current users (Ptrend = .03). Results were similar in analyses restricted to patients with a history of osteoporosis or osteopenia.Conclusions Bisphosphonate use was associated with a substantial reduction in risk of contralateral breast cancer. If this finding is confirmed in additional studies, nitrogenous bisphosphonate therapy may be a feasible approach for contralateral breast cancer risk reduction.
Journal of the National Cancer Institute , résumé, 2011