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Long-term outcomes after neoadjuvant trastuzumab and chemotherapy for HER2+ breast cancer.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Neoadjuvant chemotherapy (C) plus trastuzumab (H) improves pathologic complete response (pCR) rate over C alone. Whether pCR after CH is predictive of survival is not known. We evaluated long-term (LT) follow-up of survival and cardiotoxicity outcomes from neoadjuvant trials of CH for HER2+ breast cancer. Methods: Patients (pts) with HER2+ stage II-III breast cancer were enrolled on 2 neoadjuvant phase 2 trials between 1999-2003. Treatment consisted of either 12 wks paclitaxel/H (TH) with optional adjuvant C, or 12 wks vinorelbine/H (NH) with optional adjuvant C+/-H x 40 wks. pCR was defined as absence of invasive disease in breast and lymph nodes at surgery. LT follow-up on recurrence, survival, and cardiotoxicity endpoints was performed through chart review. Results: Of 88 enrolled pts, 78 were confirmed HER2+ and completed CH without progression (TH 32 pts, NH 46 pts). Median age was 45y. 63% were hormone receptor (HR) +, 37% HR-. 15 (19%) had pCR at surgery, 7 (22%) with TH, and 8 (17%) with NH. Optional adjuvant anthracycline-based C was received by 99% of pts, with adjuvant H in 72% of NH pts. Median duration of follow-up is 8.3y (10.2y, TH, and 7.8y, NH). 22 pts have recurred (5 local, 15 distant, and 2 both sequentially) and 15 have died from breast cancer for a total of 21 disease-free survival (DFS) events. In pts with pCR, 4-year DFS was 93.3% (95% CI 61-99); in those without pCR, 75.4% (CI 63-84). Without adjuvant H, 4-year DFS in pts with pCR had too few events to estimate, in those without pCR 72.2% (CI 55-84). In patients who received adjuvant H, 4-year DFS in those with pCR was 85.7% (CI 33-98), in those without pCR 80.4% (CI 59-91). Of 27 pts with ejection fraction (EF) recorded during follow-up, 1 experienced symptomatic cardiac toxicity while receiving H for metastatic disease. Conclusions: LT prognosis in this cohort with stage II-III HER2+ disease and neoadjuvant CH exposure was favorable, and LT cardiotoxicity was rare. Trends suggest pts with pCR experience better outcomes than those without pCR. However, adjuvant H may confound the interaction between neoadjuvant response and LT DFS. For HER2+ tumors, as for ER+ tumors, the prognostic value of pCR may be limited by the availability of effective adjuvant therapies.
Abstracts by A. Gropper:
- Meeting: 2013 ASCO Annual Meeting | Abstract No: 1117