Oral bisphosphonates linked to reduced incidence of invasive breast cancer
Reported December 18, 2009
Findings from an analysis of the Womens Health Initiative showed that women taking oral bisphosphonates for osteoporosis were less likely to develop invasive breast cancer.
A total of 2,216 of 151,592 postmenopausal women enrolled in the initiative were taking either alendronate (89.7%) or etidronate (10.1%) at their entry into the program.
Rowan Chlebowski, MD, PhD, a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-University of California, said that researchers found a mean 32% fewer breast cancers among women using bisphosphonates compared to women who did not.
Chlebowski presented the findings during the 32nd Annual CTRC-AACR San Antonio Breast Cancer Symposium.
The rate of invasive breast cancer was 4.38 per 1,000 person-years of follow-up for non-bisphosphate users compared to 3.29 per 1,000 person-years for bisphosphonate users.
Oral bisphosphonate use may directly inhibit breast cancer incidents, Chlebowski said. There are ongoing randomized trials in an adjuvant setting looking at contralateral breast cancer and may, in a year or so, be able to provide confirmation for this observational cohort finding.
Using the hip fracture risk score to control for bone mineral density between bisphosphonate users and non-users, the researchers observed 30% fewer estrogen receptor-positive cancers and 34% fewer entry receptor-negative cancers in bisphosphonate users.
Reference: Chlebowski R. Oral bisphosphonate and breast cancer: Prospective results from the Women’s Health Initiative. Paper #21 Presented at: 32nd Annual CTCR-AACR San Antonio Breast Cancer Symposium; Dec. 9-11, 2009. San Antonio, Texas.
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