Background: Compared with invasive ductal carcinoma, invasive lobular carcinoma of the breast is considered by many to be a more indistinct and multicentric form of cancer that is detected later and is treated less optimally by breast-preservation techniques. This study analyzed the presentation, treatment trends, and survival rates of women who had invasive lobular and ductal breast carcinoma. The objective was to determine the utility of breast-preservation therapy for invasive lobular carcinoma by analysis of historic data on tumor features and survival. Study Design: Data on 291,273 women diagnosed with invasive carcinoma between 1985 and 1993 were obtained from the National Cancer Data Base. Analysis included the patient's age at diagnosis; tumor histology, anatomic site, diameter, grade, and stage; treatment; and disease status 5 years after diagnosis. Results: The mean patient age at diagnosis was 61.0 years for invasive ductal carcinoma, 63.0 years for invasive lobular carcinoma, and 60.6 years for tumors with combined histology. The anatomic location, tumor diameter, and tumor grade were similar for each histotype. Breast-preservation therapy was less frequent for invasive lobular carcinoma. The 5-year overall survival and local disease- free survival rates for women treated with breast preservation were similar for invasive ductal carcinoma (84% overall survival; 97% disease-free survival) and invasive lobular carcinoma (87% overall survival; 98% disease- free survival). Conclusions: Invasive lobular carcinoma presents with a similar age distribution, anatomic subsite, diameter, and grade as invasive ductal carcinoma. Breast preservation is selected less commonly for women who have invasive lobular carcinoma, but this choice of therapy does not compromise the disease-free or overall survival status of this group of patients.