The importance of histologic type on breast cancer survival.

Breast cancer is a morphologically and genetically heterogeneous disease. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute provides the large number of cases necessary to study individual histologic types of female invasive breast cancer that for practical reasons are otherwise unattainable. Attention was specifically focused on 4082 cases of mucinous adenocarcinoma and 139,154 cases of infiltrating duct carcinoma identified for the years 1973-1990. Life table analyses were conducted to compare survival by histologic type using death due to breast cancer as the outcome; Cox proportional hazards analysis was used to adjust for important covariates. Findings were that women diagnosed with mucinous adenocarcinoma have a rate of mortality due to breast cancer that is 0.38 that of the rate of women diagnosed with infiltrating duct carcinoma (95% confidence interval 0.34-0.42). We conclude that histologic type is important to consider in the prognosis and treatment of women diagnosed with breast cancer.