Do stem cell markers have significant implication in breast cancer? Immunohistochemical study for CD44 and CD24.

Abstract Abstract #5058 Background: We reported that breast cancer expressing CD44+CD24-/low showed a favorable prognosis in contrary to the in vitro/in vivo studies. We further followed this data up to 99 months and analyzed it according to CD44 expression, CD24 expression and hormone expression. Design: immunohistochemical stainings for CD44s and CD24 as well as prognostic markers including estrogen receptor, progesterone receptor, p53, and Her2/neu were done using tissue microarray blocks containing 645 consecutive cases of invasive breast carcinomas from 1993 to 1998. Mean follow up periods were 99.5 months. Cases were categorized into four subgroups (CD44-/CD24+, CD44+/CD24+, CD44-/CD24-, CD44+/CD24-) based on the immunohistochemical staining results and compared them with clinicopathologic parameters. Immunostainings for CD44s and CD24 interpreted as positive if at least 1% of tumor cells show distinct membranous and/or cytoplasmic stainings. In the positive group of CD24, we categorized it as three subgroups according to the degree of positivity. Results: CD44+CD24-/low group showed inversely associated with lymph node metastasis and the tumor stage than other subgroups (p=0.001 and p=0.018, respectively). And CD44+CD24-/low group was showed an increase in disease free survival and overall survival (p=0.003, p=0.002) In the subgroup analysis of CD24 expression (0, grade 1, grade 2, grade 3), the incidence of metastasis and death was more frequently observed in the cases with the higher expression of CD24. (DFS: p=0.03, OS: p=0.001). With respect to the CD44, CD44- group showed frequent metastasis and death (p=0.01, both) however, for the receptor positive groups, not CD44 but CD24 expression resulted negatively to the overall survival significantly(p=0.01, Relative risk=1.90) on multivariate analysis. For the receptor negative groups, especially triple negative group, lack of CD44 expression made overall decreased to 50%(p=0.03, hazard ratio=0.5) Conclusion: In contrast to cell line studies, CD44+CD24-/low phenotype is considered a favorable prognostic subgroup of breast cancer associated with less frequent nodal metastasis, lower tumor stage and infrequent distant metastasis. For receptor positive breast caner, CD24 expression effect DFS, OS significantly, and For receptor negative group, especially triple negative breast cancer, Lack of CD44 expression made and effect OS inversely. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5058.