Evaluation of the Co-Expression of the Cancer Stem Cell Marker ALDH1 and of HER2 as a Predictor of Adjuvant Trastuzumab Response in Breast Cancers of Women in NSABP B31

OBJECTIVES:

Primary

• To determine if stem cellness identifies a poor prognostic subgroup of women with early-stage breast cancer who have been uniformly treated with either adjuvant doxorubicin hydrochloride & cyclophosphamide followed by paclitaxel (the "control arm" of B31), or the same chemotherapy plus trastuzumab.

Secondary

• To conduct exploratory analyses to assess, to the extent possible, if co-localization of stem cellness, as determined by ALDH1 positivity, and HER2 identifies a group of patients previously considered to have HER2-negative cancers (using classical definitions) who benefit from adjuvant trastuzumab.