Is ypT0/isn0 acceptable for Japanese population? JBCRG’s perception.

Abstract

e12011 Background: Pathologic complete response (pCR) is a proposed surrogate endpoint for predicting disease-free survival (DFS) or overall survival (OS). However, several definition of pCR has to be used in NAC studies, and In Japan, JBCRG conducted several study of neoadjuvant chemotherapy using QpCR(including focal residual invasive tumors as pCR) between 2002 and 2006. Methods: The regimen studied were FEC followed by Docetaxel (75 mg/m2)(FEC-DOC) (n = 186), FEC-DOC (100 mg/m2) (n = 37),DOC followed by FEC (n = 130), JBCRG-01, 02, 03, respectively. Three studies were pooled and analysed for pCR rates, DFS, OS in terms of several pCR definition and subtypes. We included patients when subtype and long-termfollow-up available for DFS and OS. We compared 5 pCR definitions: absence of invasive cancer and in situ cancer in the breast irrespective of nodal involvement (ypT0, SpCR), absence of invasive cancer and in situ cancer in the breast axillary nodes (ypT0ypN0, SpCRbn), absence of invasive cancer in the breast irrespective of nodal involvement (ypT0/is, CpCR), absence of invasive cancer in the breast axillary nodes with DCIS allowed (ypT0/isypN0, CpCRbn), and QpCR. Subtypes were classified into luminal (ER+ and/or PgR+, HER2-), luminal –HER2 (ER+ and/or PgR+, HER2+), triple-positive (TP) (ER-,PgR-, HER2-), HER2 (ER-, PgR-, HER2+) by using immunohistochemically stained specimen obtained by core needle biopsy. Results: Number of patients in each subtypes were as follows; luminal 206 (58%), luminal -HER2 34(10%), HER2 40 (11%), TN 73 (21%). pCR rate was significantly high in HER2 and TN irrespective of pCR definition (p <0.05). At median follow up 75M, pCR group showed significantly better prognosis. Cox multivariate analysis showed pCR (irrespective of pCR definition) and subtype were the significant predictors of prognosis among study, age, tumor size. Conclusions: Subtype is a useful predictive biomarker of pCR, and ypT0/isn0 is acceptable for Japanese population.