Central nervous system metastases in a cohort of metastatic breast cancer patients treated with trastuzumab

Background Several analyses suggest an increase of brain metastases in HER2 over-expressing breast cancers treated with trastuzumab as compared to historical series of unselected patients. Patients and methods We analyzed the incidence of central nervous system (CNS) metastases in 78 patients with HER2 over-expressing breast cancer treated with trastuzumab between July 2000 and June 2006 at the Oncology Department of University Federico II in Naples. We also characterized and compared patients with and without CNS involvement. Results The median follow-up was 35.3 months (95% CI 26.3-44); median overall survival was 56 months (95% CIs 46-nr); 5 patients showed CNS involvement before trastuzumab therapy while 31 developed CNS metastases during trastuzumab treatment. The median overall survival after CNS metastases was 25.4 months (95% CIs 15.2-nr); patients with CNS lesions showed worse overall survival than patients without CNS lesions (39.1 vs. 75 months, p=0.005). Conclusion CNS metastases are common events in patients with metastatic HER2 over-expressing breast cancer treated with trastuzumab; the impact on survival is detrimental even if survival after CNS metastases is longer than historical reports. Appropriate investigation of the role of CNS imaging screening and the prophylactic treatment strategies for CNS represents a priority research in this setting.