The Frequency of and Risk Factors for the Use of Bisphosphonates in the Adjuvant Setting of Primary Breast Cancer in Germany

PURPOSE The aim of this cross-sectional health care study (use of bisphosphonates in primary tumors of the mammae, EBisMa) is to determine how often bisphosphonate medication is used in patients with non-metastatic primary breast cancer treatment, but who do not suffer from osteoporosis. Furthermore, we describe patients' characteristics and the most frequently used type of bisphosphonate in adjuvant therapy. MATERIALS AND METHODS The study population included primary breast cancer patients of four breast centers in northern Germany. Data on bisphosphonate therapy were collected by use of patient questionnaires; clinical data were extracted from the registers. Patients with and without prescribed bisphosphonate adjuvant treatment were tested for statistically significant differences regarding their characteristics. RESULTS Four hundred seventy-four of 663 contacted patients participated in the study. Thirty-nine out of 474 patients (9.6%) were on adjuvant bisphosphonate therapy. Zoledronic acid was the most frequently reported bisphosphonate used for prevention of bone metastases. Compared to patients who did not report bisphosphonate medication, women who did report bisphosphonate therapy had a significantly higher advanced tumor stage (p < 0.001). Both the T2-T4 stage and N+ stage remained significant predictors in multivariate-adjusted regression models. CONCLUSION Bisphosphonates are rarely used in the adjuvant treatment of primary breast cancer. Patients with advanced tumor stage were more likely to use bisphosphonates in the adjuvant treatment of primary breast cancer. Further research is needed to identify patients who may benefit most from adjuvant bisphosphonate treatment.