[Radiation therapy for brain metastases from breast cancer by histological classification]

One hundred thirteen patients with metastatic brain tumor from breast cancer who were treated with external irradiation between 1989 and 1997 at Cancer Institute Hospital were studied. The patients were all histopathologically proven to have invasive ductal carcinoma (scirrhous type 54 cases, papillotubular type 18, solid-tubular type 41). The patients were evaluated for efficacy and histopathological subtypes. The time interval between the diagnosis of breast cancer and brain metastases was 53.6 months for the scirrhous type, 75.0 months for the papillotubular type, and 35.5 months for the solid-tubular type. The time interval between the diagnosis of initial distant metastases and brain metastases was 14.3 months for the scirrhous type, 22.5 months for the papillotubular type, and 12.5 months for the solid-tubular type. Efficacy rates (CR + PR) for external irradiation of the brain metastases were 40.0% for the scirrhous type, 66.7% for the papillotubular type, and 36.6% for the solid-tubular type. The papillotubular type had a favorable efficacy rate compared with the other two types. Median survival time (MST) from the start of treatment for brain metastases and one-year survival rate were 5 months and 11.1% for the scirrhous type, 7 months and 41.5% for the papillotubular type, and 4 months and 28.3% for the solid-tubular type, respectively. No statistically significant difference between survival rates was observed among the histopathological types. Univariate analysis showed performance status, number of metastatic tumors, and existence of extracranial metastases without bony metastasis to be significantly related to prognosis. Multivariate analysis showed only extracranial metastases without bony metastases to be related to prognosis.