The delimitation of tubular carcinoma of the breast

Five hundred consecutive breast carcinomas from the first screening round of the Breast Cancer Detection Demonstration Project were studied quantitatively and semiquantitatively for features relevant to the diagnosis of tubular carcinoma. Tubularity was defined as the proportion of tumor cells that were adjacent to an open lumen. Nuclear morphology and mitotic activity were graded 1 to 3, and the presence of apocrine snouts as absent, few, common, or prominent. In plots and statistical cluster analysis, tubular carcinoma appears as part of a continuous spectrum of morphologies and not as a distinct entity. In multivariate analysis, apocrine snouts had no significant association with either nodal status or deaths of breast cancer. Tumors with 70% or greater tubularity by our definition and mitosis and nuclear grades 1 were not associated with either nodal metastases or deaths of breast cancer. The question is raised whether tubular carcinoma at the benign end of a spectrum shades into benign glandular proliferations, with particular reference to microglandular adenosis. A uniform and precise definition of tubularity is needed for the attainment of sufficient collective experience to delimit tubular carcinoma both from more aggressive carcinomas and from benign proliferations.