Correlation Of Various Pathologic Complete Response (Pcr) Definitions With Long-Term Outcome And The Prognostic Value Of Pcr In Various Breast Cancer Subtypes: Results From The German Neoadjuvant Meta-Analysis

1028 Background: Definition of pCR and its prognostic value in breast cancer subgroups has not been studied formally. We therefore correlated pCR and survival using our meta-database of 7 German neoadjuvant trials using anthracyclines, taxanes regimen with or without trastuzumab. Methods: 6,377 Pts with operable or locally advanced, non-metastatic breast cancer from GeparDuo (N=907), GeparTrio-Pilot (N=285), GeparTrio (N=2072); GeparQuattro (N=1495). AGO 1 (N=666), Prepare (N=733) and Techno (N=217) were analyzed. Pts were 50+ years in 50.6%, had cT1/2 tumors in 71.2%, cN- disease in 49.9%, lobular histology in 13.6%, G1/2 in 59.9%, ER pos in 62.4%, PR pos in 53.7%, HER2 neg in 69.8%. 1466 (23%) relapses and 775 (12.2%) deaths were observed during a median follow up of 42 (0−127) months. Log rank tests and Cox regression (CR) analysis were performed. Results: DFS was superior in Pts with ypT0/ypN0 (=pCR) (N=955) compared to Pts with ypTis/ypN0 (N=309) (p=0.001) and to Pts with ypT≥1 or ypN+ residual disease (N=5112) (p<0.0001). ypT and ypN stage separated multiple distinct prognostic subgroups (p<0.0001). Histologic breast tumor regression (Sinn) failed to provide further information (CR: p=0.28). pCR was prognostic for DFS in the following subgroups: ductal (p<0.0001), non-ductal/non-lobular types (p<0.002), G2 (p=0.013), G3 (p<0.0001), ER− (p<0.0001); ER+/G3 (p=0.003), PgR− (p<0.0001), ER−/PgR+ (p=0.008); ER−/PgR− (p<0.0001), HER2+ (p<0.0001), HER2− (p<0.0001), ER+/HER2− (p=0.04), Rec+/HER2− (p=0.025); Rec−/HER2− (p<0.0001), Rec−/HER2+ (p<0.0001), but not in the following subgroups: lobular (p=0.7), G1 (p=0.8), ER+ (p=0.14), ER+/G1 (p=0.8), ER+/G2 (p=0.9), PgR+ (p=0.08), ER+/PgR+ (p=0.3), ER+/PgR− (p=0.09), ER+/HER2+ (p=0.9), Rec+/HER2+ (p=0.445). Similar results were obtained for overall survival. Conclusions: pCR should be conservatively defined as ypT0ypN0 excluding DCIS. ypT and ypN stages, but not regression grades provide additional prognostic information. pCR strongly correlates with DFS in higher risk groups, but not in luminal A-like and ER+/HER2+ tumors.