[On the correlation between histological and cytological diagnosis, and the intrinsic 5 subtypes]

Japanese General Rules presented by the Japanese Breast Cancer Society have been long time applied in Japan. This classification uniquely adds subtypes into the group of invasive ductal carcinomas (IDC) and reported to be correlated to patients' clinical course. The latest St. Gallen consensus meeting reported the use of 5 molecules, and introduced alternative definition in the breast cancer classification. The purpose of this study is to relate the Japanese subgrouping of IDC with the 5 subtypes and to investigate whether these classifications could predict early and late recurrence and whether cytological diagnosis is influenced by the tumor phenotypes. Analyzing 127 cases, we observed that the Ki-67 labeling index (LI) of the 5 subtypes, luminal A, luminal B-Her2--/- Her2+, Her2-subtype and basal-like, is increased in this order. Though the Japanese histological groups, papillotubular, solid-tubular and scirrhous, included more or less those subtypes, the luminal types were more represented in papillotubular and scirrhous subtypes, and the solid-tubular type in non luminal subtypes. The Ki-67 LI 14% served as a cutoff for differentiating invasive from non-invasive ductal carcinomas. Breast cancers recur within 5 years after the clinical onset when the Ki-67 LI exceeded 14%. These data suggest that, (1) the intrinsic subtyping is an accurate modality in diagnosing breast cancers, (2) it can predict the recurrence duration, (3) the solid-tubular type of the Japanese classification is likely an aggressive form among breast cancers, and (4) the cytological diagnosis is presently a powerful tool in determining malignancy.