Pathology of preinvasive and excellent-prognosis breast cancer.

Our review of recent developments in breast cancer emphasizes clinical utility of tissue samples from patients. We highlight indicators of increased cancer risk and lesions without metastatic capacity at time of detection (but of sufficient risk of attaining metastatic capacity that treatment is mandated, ie, ductal carcinoma in situ). This review also includes invasive lesions with little capacity for metastatic behavior and indicators of low malignant potential. Histologic criteria for their recognition, as well as biologic and clinical characterization, are discussed. Several papers reviewing the usefulness of histologic grading, emphasizing mitotic counts and definitions of microinvasion, are included.