[Histological classification of breast cancer]

The characteristics of histological classification of breast cancer by Stewart F.W., WHO and Japan Mammary Cancer Society (published in 1971 and revised in 1984) are discussed. The classification of JMCS is fundamentally the same as WHO classification with a subclassification of invasive ductal carcinoma. Invasive ductal carcinoma has three subgroups; papillotubular, solid-tubular and scirrhous carcinoma. In these three subgroups, papillotubular carcinoma shows mainly ductal spread, well histologic differentiation, the lowest lymph node metastasis and the best prognosis. Scirrhous carcinoma shows diffuse stromal infiltration, poor histologic differentiation, the highest metastasis and the worst prognosis. Solid-tubular carcinoma with expansive stromal invasion shows intermediate biological behavior. Thus, the JMCS classification contains in itself not only histologic type but also the mode of spread, grade of histologic differentiation, ratio of lymph node metastasis and prognosis.