The purpose of this study is to evaluate the response to and benefit of first-line metastatic treatment (including re-exposure to trastuzumab) for patients relapsing after exposure to adjuvant trastuzumab (AT). All HER2-positive breast cancer cases relapsing after exposure to AT at our institutions were identified.
Clinico-pathologic details, pattern of relapse, and treatment in the metastatic setting were documented. Response to treatment and outcome were assessed.
Twenty-nine relapses were recorded. The median time to relapse was 18.4 months from diagnosis, and 8.7 months from AT initiation.
At a median time of observation of 9.9 months, 18 patients had progressed on first-line therapy. The median time-to-progression (TTP) was 8.6 months.
Fifteen patients received trastuzumab as first-line treatment, with no statistical difference in TTP between this group and those not re-exposed to trastuzumab. TTP was not statistically different between those relapsing on or after AT.
Overall survival was longer for those who relapsed after completion of 1 year of AT as well as those who received further trastuzumab at relapse; however, this did not reach statistical significance. Overall survival was longer in patients who relapse after completion of AT and who received further trastuzumab at progression.