Long-Term Analysis of Ab-2 (Clone SN3b) Immunoreactivity as a Prognostic Factor in Breast Carcinoma

Abstract

Background: CD24 expression has been described as a significant prognostic factor in multiple solid tumours. Most of these studies have, however, been undertaken using the Ab-2 antibody (clone SN3b), which detects a CD24-associated carbohydrate, and not the CD24 protein itself. Although its biological identity remains unclear, its prognostic significance means that detection of this carbohydrate may, nonetheless, be clinically relevant. Methods: 133 breast carcinomas were selected (pT1-2 pN0-2 M0, no secondary carcinoma, no contralateral carcinoma) from a previous SN3b expression study on a larger cohort of breast carcinomas. After updating data on follow-up observations, we carried out univariate and multivariate analysis of the prognostic significance of SN3b for total and breast cancer-specific survival. Results: A statistically significant correlation between cytoplasmic SN3b immunoreactivity and positive node status was found. Cytoplasmic SN3b also has node status-independent prognostic significance. Total survival exhibits a statistically significant dependency on cytoplasmic SN3b even for pN0 cases. Conclusion: The independent prognostic value of CD24 as detected by Ab-2/clone SN3b could replace the diagnostic axillary dissection in breast carcinoma patients if this was confirmed in further studies. Also, clarifying the exact epitope of this interesting antibody is more than warranted.