The efficacy of
trastuzumab beyond metastatic
disease progression (PD) is controversial. We retrospectively analyzed 213 patients with HER2-positive metastatic
breast cancer treated with
trastuzumab-based
therapies between November 1998 and December 2010. Out of 213 patients, 134 (58%) had received
trastuzumab consecutively for at least 1 year and 154 of 213 patients (67%) had received two or more lines of consecutive
trastuzumab-based
therapy beyond PD. For these subgroups of patients, we examined the correlation between patients' survival and time to first
tumor progression (
TTP). Among 134 patients who received
trastuzumab for at least 1 year, 66 (49%) never had PD within the first year of treatment, whereas 68 (51%) had PD at least once within the first year. The estimated 2-year overall survival (OS) after 1 year was 82% for those who had no PD during the first year (median OS 5.1 years) and 70% for those who had PD (median OS 2.6 years) (P<0.0001). Among 154 patients who received two or more lines of consecutive
trastuzumab-based
therapy beyond PD, we calculated a median first
TTP of 8.7 months. In terms of survival after first progression, patients with a longer first
TTP (≥8.7 months) had better survival compared with those who had a shorter first
TTP (39 months, 95% CI 31-63; vs. 28 months, 95%
CI 22-32; P=0.0004). T-based
therapy was well tolerated and only five patients experienced a
cardiac event. Our retrospective data suggest that treatment with
trastuzumab beyond progression is a viable option for patients with advanced HER2-positive
breast cancer, whose disease has progressed on previous
trastuzumab-based regimens.