Pathological complete response and prognosis after neoadjuvant chemotherapy for HER2-positive breast cancers before and after trastuzumab era: results from a real-life cohort.

BACKGROUND

Trastuzumab was introduced a decade ago and has improved outcomes for HER2-positive breast cancer. We investigated the factors predictive of pathological complete response (pCR), prognostic factors for disease-free survival (DFS), and interactions between pCR and DFS after neoadjuvant treatment.

METHODS

We identified 287 patients with primary HER2-positive breast cancers given neoadjuvant chemotherapy (NAC) between 2002 and 2011. Univariate and multivariate analyses of clinical and pathological factors associated with pCR and DFS were performed.

RESULTS

pCR rates differed between patients receiving neoadjuvant trastuzumab treatment or not (47.7% versus 19.3%, P<0.0001). DFS also differed significantly between patients receiving adjuvant trastuzumab or not (hazard ratio=4.84, 95% CI (2.52; 9.31), P<0.001). We analysed 199 patients given neoadjuvant and adjuvant trastuzumab. Multivariate analysis identified older age and hormone receptor-negative tumours as independent predictors of pCR. T stage (hazard ratio=2.55, 95% CI (1.01; 6.48), P=0.05) and strict pCR (hazard ratio=9.15, 95% CI (1.22; 68.83), P=0.03) were independent predictors of DFS. The latter association was significant in the HR-negative subgroup (P=0.02) but not in the HR-positive subgroup (P=0.12).

CONCLUSIONS

Major pCR and DFS gains in HER2-positive BC were observed since 'trastuzumab' era. Further improvements rely on the enrollment of accurately selected patients into clinical trials.