Pathological aspects of breast cancer in Indonesian females, applying a modified who classification. A joint study between Indonesia and Japan

From the pathological aspect, we analyzed again the histological variants of breast cancer and compare them with cases from Japan. We used the classification recommended by the Japanese Breast Cancer Society, which divided the invasive ductal carcinoma of NOS (no otherwise specified) of the WHO classification into 3 subtypes, namely papillòtubular, solid-tubular and scirrhous carcinoma. We had 515 cases from Indonesia (1^st batch and 2^nd batch) treated at the Dr. Cipto Mangunkusumo National Central General Hospital (RSCM) and 445 cases from Japan, treated at the Cancer Institute Hospital (CIH). The RSCM cases had 0.97% noninvasive carcinoma, 89.14% invasive ductal carcinoma and 9.50% of the specialtypes. The CIH cases had 7.4% noninvasive carcinoma, 80.4% invasive ductal carcinoma and 11.3% of the special types. The incidence of noninvasive ductal carcinoma was lower at RSCM, with a 6.43% difference. Among the subtypes of invasive ductal carcinoma, the scirhous carcinoma was the most common in both groups (RSCM and CIH), with an incidence of50.49% (RSCM) and 43.6% (CIH). The least common at RSCM was the papillòtubular type, while at the CIH it was the solid-tubular type. Among the special types, only 5 variants were encountered at RSCM and 7 at CIH. The incidences of mucinous carcinoma and invasive lobular carcinoma were lower at RSCM, while the medullary carcinoma was higher. The incidence of Paget’s disease was also lower at RSCM.