Abstract 5178: Expression of CD44/CD24 and aldehyde dehydrogenase 1 in resected breast cancer: CD24-positivity predicts early relapse

Abstract

Abstract Background: CD44+/CD24- or aldehyde dehydrogenase 1 (ALDH1) has been suggested as potential markers for breast cancer stem cells, although little is known about its clinical implications. We evaluated the expression of CD44/CD24 and ALDH1 in breast cancer patients in both ends of the prognostic spectrum. Methods: Of 819 resected breast cancer cohort with positive estrogen receptor, ‘early relapse group’ within 5 years postsurgery and ‘no relapse group’ longer than 10 years postsurgery were defined. Paraffin-embedded tumor tissues were available in 31 early relapsed patients and 68 patients from no relapse group. CD44/CD24 and ALDH1 expression were evaluated with immunohistochemical staining. Positive criteria were designated as more than 15% tumor cell membranous staining for CD44/CD24 and more than 5% tumor cell cytosolic staining for ALDH1. Results: Early relapse group contained higher N stage and higher histologic grade than no relapse group but there were no differences in age, menopauseal status, progesterone receptor status, HER2 status, and T stage between both groups. Phenotypes of CD44/CD24 were CD44+/CD24- in one patient (1%), CD44+/CD24+ in one (1%), CD44-/CD24+ in 12 (12%), and CD44-/CD24- in 67 (68%). Four patients (4%) showed ALDH1-positivity. Due to rarity of CD44-positivity or ALDH1-positivity, staining results were simply dichotomized into CD24-positive (13%, 13/99 patients) and CD24-negative status (87%, 86/99 patients) and only the status of CD24 was further analyzed. CD24-positivity was higher in early relapse group (32%) than in no relapse group (4%). CD24-positivity was associated with negative progesterone receptor (P=0.026), higher N stage (P=0.029), and higher histologic grade (P=0.034). However, in the multivariate logistic regression adjusted by known prognostic factors, CD24-positivity was a still significant predictive factor for early relapse (hazard ratio=8.51; P=0.006). Conclusions: The incidence of CD44+/CD24- and ALDH1-positivity which are potential breast cancer stem cell markers, were low. However, in resected breast cancer, expression of CD24 was a significant predictive factor for early relapse. CD24 is worth further investigation as a novel biomarker. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5178. doi:10.1158/1538-7445.AM2011-5178