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Impact of adjuvant trastuzumab-based chemotherapy in T1ab node-negative HER2 overexpressing breast carcinomas.
Breast Cancer - HER2/ER
Session Type and Session Title:
General Poster Session, Breast Cancer - HER2/ER
J Clin Oncol 30, 2012 (suppl; abstr 601)
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: HER2 overexpression has been recognized as a pejorative prognostic factor in node negative T1ab (T1abN0) breast tumors. Randomized clinical trials have shown benefit of adjuvant trastuzumab-based chemotherapy (ATBC) for node-positive and/or greater than 1 cm (T1c or more) HER2+ breast carcinomas. There are no prospective efficacy data of ATBC in T1abN0 HER2+ tumors. Methods: We retrospectively evaluated 276 cases of T1ab node-negative HER2+ breast tumors in 8 French Comprehensive Cancer Centers. We assessed clinical, therapeutic features and outcome. We estimated the probability of disease-free survival (DFS), analyzed associations of ATBC, patient and tumor characteristics with DFS and prognosis factors using the log-rank test, multivariate analysis with logistic regression and Cox’s proportional hazards model. Results: Out of the 276 T1abN0 cases, 129 (47%) received ATBC (ATBC+) and 123 (45%) were not treated by either trastuzumab or chemotherapy (ATBC-). Of these 252 ATBC+ or ATBC- patients, decision of ATBC was associated with date of diagnosis (before or after ASCO 2005 Annual Meeting when interim results from three trastuzumab adjuvant trials were reported) and with poor prognosis features: negative hormone receptors (HR-) status, Elston-Ellis high grade, tumor size > 5 mm and age. With a median follow-up of 44 months 16 recurrences were observed (13 in the ATBC- group, 2 in the ATBC+ and 1 with adjuvant chemotherapy alone). Nine recurrences were distant metastases. A survival benefit in ATBC+ was observed with a 99% 40-months DFS versus 93% for ATBC- (logrank p-test = 0.018). In an exploratory analysis, two factors were significantly associated with worst prognosis for ATBC- that were not observed for ATBC+ : HR- status (98% 40-months DFS for ATBC+ patients versus 84% for ATBC- patients; logrank p-test = 0.0003) and presence of lymphovascular invasion (100% 40-months DFS for ATBC+ versus 73% in ATBC- cases; logrank p-test = 0.003). Conclusions: In our seriesATBC is associated with a significant reduction of risk of recurrence of T1abN0 HER2+ tumors. A clear DFS benefit of ATBC was observed in HR- tumors and/or in presence of lymphovascular invasion.