Risk reduction of endometrial and ovarian cancer after bisphosphonates use: A meta-analysis.

OBJECTIVE: Recent epidemiological studies have investigated the associations between the use of bisphosphonates and the development of endometrial cancer and ovarian cancer; these studies have shown controversial results. Hence, this meta-analysis was conducted to evaluate the changes in the risks of developing endometrial and ovarian cancers after using bisphosphonates based on current evidence. METHODS: A comprehensive search was performed in the MEDLINE, EMBASE, and Web of Science databases through January 2017. The summary relative risk (RR) estimates for the effects of the use of bisphosphonates on the risks of developing endometrial and ovarian cancers were calculated using a random-effects model. RESULTS: Seven studies were included with a total of 6471 endometrial cancer cases (7 studies with 213,920 participants) and 6783 ovarian cancer cases (4 studies with 105,507 participants). This meta-analysis suggested that any use of bisphosphonates was associated with a significant 27% reduction in the risk of endometrial cancer (RR = 0.73, 95% CI: 0.58-0.93, P = 0.012), but the reduction in the risk of ovarian cancer (RR = 0.81, 95% CI: 0.58-1.14, P = 0.227) was not significant. The protective effects of the use of bisphosphonates against endometrial cancer are mainly found in postmenopausal women (RR = 0.53, 95% CI: 0.34-0.93, P = 0.012) or in those who have taken bisphosphonates for longer than 1 year (RR = 0.57, 95% CI: 0.35-0.93, P = 0.024). CONCLUSION: This meta-analysis suggests that the use of bisphosphonates is associated with a reduction in the risk of endometrial cancer but not ovarian cancer.