Duration of anti-HER2 blockage therapy may improve survival in HER2 positive metastatic breast carcinoma patients.

Purpose: The duration of anti-HER2 blockage therapy in metastatic breast cancer patients is still unclear. We aimed to evaluate the effect of the anti-HER2 blockage therapy duration and other factors on survival in HER2 positive metastatic breast carcinoma (MBC) patients.
Methods: The medical records of 193 HER2 positive MBC patients, who did not have the opportunity to receive adjuvant trastuzumab therapy but had received trastuzumab in the metastatic setting were retrospectively evaluated.
Results: The median age at diagnosis was 45.0 years (range 21-83). Ninety-two (47.7%) patients received palliative trastuzumab < 6 months median, whereas 101 patients received trastuzumab ≥ 6 months median. The median number of trastuzumab cycles was 8 (range 1-51). Median survival after breast cancer recurrence was 31.0 months (range 24.3-37.7). The duration of trastuzumab therapy had a significant impact on the prognosis of recurrent breast cancer (22.0 vs 49.0 months, for ≤ 6 months of treatment duration, respectively; p<0.0001). Survival after breast cancer recurrence for the patients who received lapatinib plus capecitabine vs those who did not was significantly different (59 patients, p=0.005). Moreover, there was a statistically significant relationship between prolonged lapatinib plus capecitabine combination therapy and improved survival after disease recurrence (p=0.022). In the multivariate Cox regression analysis, treatment with trastuzumab > 6 months (p=0.003) was the only independent prognostic factor for survival after breast cancer recurrence.
Conclusion: The duration of anti-HER2 blockage therapies, especially with trastuzumab, seems to improve survival of HER2-positive metastatic breast cancer patients who were not previously treated with adjuvant trastuzumab, regardless of other therapies.