Purpose: To summarize current evidence of the association of bisphosphonate use with breast cancer risk, we used a systematic review and meta-analysis of observational studies to explore this issue.
Methods: A comprehensive search was conducted on PubMed, EMBASE, and the Cochrane Library. Pooled relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using the random effects model.
Results: Bisphosphonate use was associated with a 16% lower breast cancer risk (pool RR0.84, 95%CI 0.77-0.90, n = 8). A protective effect of bisphosphonate was found in cohort studies (RR 0.85, 95%CI 0.80-0.90, n = 4) and case-control studies (RR 0.78, 95%CI 0.64-0.96, n = 4).We also found that the use of bisphosphonate resulted in a statistically significant reduction in all breast cancer risk (RR 0.87, 95%CI 0.81-0.93) and greater reduction in invasive breast cancer risk (RR 0.78, 95%CI 0.68-0.91) and contralateral breast cancer risk (RR, 0.41; 95% CI, 0.20-0.84).With respect to the type of bisphosphonate, we found that alendronate and etidronate resulted significant reduction in breast cancer risk. The short-term use of bisphosphonate (<1 y) led to nonsignificant change (RR 0.93, 95%CI 0.86-1.00), but a significant 26% reduction of breast cancer risk was noted with long-term use (>1 y) (RR 0.74, 95%CI 0.66-0.83).
Conclusions: Our results supported bisphosphonate as being effective in preventing breast cancer, including invasive and contralateral breast cancer. Furthermore, the long-term use (>1 y) of bisphosphonate was more significant in lowering breast cancer risk.
Keywords: bisphosphonate; breast cancer; cancer risk; meta-analysis; pharmacoepidemiology.
Copyright © 2017 John Wiley & Sons, Ltd.