Abstract P4-12-20: Clinical outcomes of patients with recurrent HER2-positive breast cancer after exposure to adjuvant trastuzumab

Abstract

Abstract Background: Trastuzumab has become the cornerstone of adjuvant therapy for patients with HER2-positive breast cancer, as it has significantly impacted on overall survival for these patients. Unfortunately, not all patients are cured, and recurrences occur in up to 13% of patients. In the post-trastuzumab era, long-term outcomes for HER2-positive breast cancer patients who develop recurrent disease after exposure to adjuvant trastuzumab is unknown. Methods: We retrospectively identified patients with stage I-III HER2-positive breast cancer treated at The Ohio State University Medical Center from 1995-2011. Patients were divided into two groups: those exposed to adjuvant trastuzumab, and those who never received adjuvant trastuzumab. Medical records were reviewed to obtain demographic data, disease status at diagnosis, adjuvant and metastatic therapeutic regimens, date and location of recurrent disease, date of last follow-up and vital status. Time-dependent analyses were carried out using Kaplan-Meier estimates. Results: Six hundred and sixty-two patients were initially identified and included in the analysis. Of the 374 patients who did not receive adjuvant trastuzumab, 96 patients had recurrence (26%). There were 288 patients who received adjuvant trastuzumab, with 33 patients developing relapse (11%). In the patients who received adjuvant trastuzumab and subsequently recurred, there was a higher incidence of CNS recurrence (n = 8; 24%) than those who did not receive adjuvant trastuzumab (n = 10; 10%). Those that received adjuvant trastuzumab also had fewer bone metastases (n = 3; 9%) than the patients who did not receive adjuvant trastuzumab (n = 29; 30%). There was no difference in overall survival in patients with metastatic progression after exposure to adjuvant trastuzumab compared to patients with metastatic HER2-positive breast cancer without prior adjuvant trastuzumab (p = 0.41). Of the 33 patients who relapsed after adjuvant trastuzumab, the majority received HER2-targeted therapy in the form of trastuzumab or lapatinib (n = 22; 67%). Eleven patients received trastuzumab-based therapy and 9 received lapatinib-based therapy. Two patients received the combination of trastuzumab and lapatinib. The remainder received cytotoxic therapy alone (n = 3; 9%), endocrine therapy (n = 1; 3%) or local therapy (surgery or radiation) (n = 4; 12%). Three patients received no therapy. Conclusion: There was no difference in overall survival for HER2-positive breast cancer patients who recur after adjuvant trastuzumab compared to metastatic patients without exposure to adjuvant trastuzumab. CNS disease as the first site of recurrence occured more frequently in patients who had received adjuvant trastuzumab than in those who were not previously exposed to trastuzumab. Continued HER2-targeted therapy after relapse on adjuvant trastuzumab was the regimen of choice in the first-line metastatic setting. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-20.