Bisphosphonates and pathologic complete response to taxane- And anthracycline-based neoadjuvant chemotherapy in patients with breast cancer

BACKGROUND: Several studies have suggested that bisphosphonates have an antitumor effect. In the current study, the authors sought to evaluate whether the use of bisphosphonates increased the rate of pathological complete response (pCR) in patients with breast cancer. METHODS: The authors identified 1449 patients with breast cancer who were receiving taxane- and anthracycline-based neoadjuvant chemotherapy between 1995 and 2007 at The University of Texas MD Anderson Cancer Center. Patients who received bisphosphonates for osteopenia or osteoporosis while receiving chemotherapy were also identified. The primary outcome was the percentage of patients achieving a pCR. Groups were compared using the chi-square test. A multivariable logistic regression model was fit to examine the relation between the use of bisphosphonates and pCR. An exploratory survival analysis using the Kaplan-Meier method was performed; groups were compared using the log-rank test. RESULTS: Of the 1449 patients included, 39 (2.7%) received bisphosphonates. Those receiving bisphosphonates were older (P < .001) and less likely to be obese (P = .04). The pCR rate was 25.4% in the bisphosphonate group and 16% in the nonbisphosphonate group (P = .11). In the multivariable model, patients treated with bisphosphonates tended to have higher rates of pCR (odds ratio, 2.18; 95% confidence interval, 0.90-5.24); however, the difference was not found to be statistically significant. With a median follow-up of 55 months (range, 3 months-145 months), no differences in disease recurrence or survival were observed. CONCLUSIONS: The use of bisphosphonates at the time of neoadjuvant chemotherapy was not found to be associated with a statistically significant increase in the rates of pCR. The observed estimates suggest a positive effect; however, the small percentage of patients receiving bisphosphonates likely affected the power to detect a statistically significant difference.