Clinical Significance of Subcellular Localization of Maspin in Breast Carcinoma: An Immunohistochemical Study Using Two Different Antibodies

Background Maspin is known to be a tumor suppres-sor protein: however, its prognostic value in patients with breast cancer remains controversial. The key in-fluential factors contributing to this complexity may be the differences in antibodies used, as well as the positive criteria and sample size. To date, no study has investi-gated the prognostic significance of maspin expression by using two different antibodies in the same cohort. We aimed to clarify whether differences in antibodies could influence on the prognostic value of maspin in breast cancer patients.Methods Immunohistochemical analyses using an anti-maspin antibody (clone G167-70) were performed on 164 resected specimens of invasive carcinoma of no special type (NOS). The correlation with clinicopatho-logical factors was compared to previous results using clone EAW24, with longer follow-up duration.Results The subcellular localization of maspin expression was as follows: cytoplasmic-only staining, 3 cases (1.8%), pancellular staining, 43 cases (26.2%); and no staining, 118 cases (72.0%). No nuclear-only staining was observed. There was no significant cor-relation between clinicopathological characteristics and the pancellualr expression of maspin. The pancellular expression group showed a significantly longer disease -free survival (DFS) than the other groups (P = 0.046). When clone EAW24 was used, the cytoplasmic-only staining group showed significantly shorter DFS than the pancellular staining group (P = 0.003).Conclusion Clone EAW24 may be superior to clone G167-70 in selecting breast carcinoma with an aggres-sive phenotype, while clone G167-70 may be superior to clone EAW24 in selecting non-aggressive breast carcinoma.