Outcome of patients with early breast cancer receiving nitrogen-containing bisphosphonates: a comparative analysis from the Metropolitan Detroit Cancer Surveillance System.

BACKGROUND: Preclinical data suggest that bisphosphonates exhibit antitumor activity. However, clinical studies indicated conflicting results. In this study, we compared the overall survival (OS) of postmenopausal patients with nonmetastatic invasive breast cancer who received any of the second-generation nitrogen-containing bisphosphonates for osteopenia or osteoporosis, with the survival of those who did not. PATIENTS AND METHODS: We conducted a retrospective study at the Wayne State University/Karmanos Cancer institute (KCI) in Detroit, Michigan and extracted data from the Metropolitan Detroit Cancer Surveillance System (MDCSS), a Surveillance, Epidemiology and End Results (SEER) registry. Patients > 50 years of age with stage I, II, or III invasive breast cancer between the years 2000 through 2003 were included. Information regarding medications was extracted from the patients' medical records.
RESULTS: A total of 696 women with stage I-III breast cancer were included. Ninety-seven women (14%) used nitrogen-containing bisphosphonates. The difference in OS between bisphosphonate users and nonusers was not statistically significant (P = .32) at 3 years. After adjusting for differences between the groups in age, stage of disease, hormone receptor status, endocrine therapy, vitamin D, and calcium use, there was a marginally significant (P = .07) difference in survival; bisphosphonate users had poorer survival than nonusers.
CONCLUSION: Our results indicate that the use of nitrogen-containing bisphosphonates is not associated with improved OS in patients with nonmetastatic breast cancer, even after adjusting for known prognostic factors, but with a marginally worse OS. Further research is awaited to clarify the role of bisphosphonates in the adjuvant setting.