A clinicopathologic study of atypical lesions of the breast

Following the detection of non‐infiltrating cancer, there have been more extensive microscopic studies for various atypical lesions of the breast. At Memorial Hospital, 296 patients with these lesions were seen during the period 1960 to 1972. These lesions were found more often in middle aged women than is the case in average cancer patients, commonly seen in nulliparous women, in patients in whom breast cancer was found in the opposite breast, and in patients with a history of breast cancer in the family. The clinical and mammographic findings are quite similar to those in non‐infiltrating cancer. Occasionally, these lesions are quite difficult to distinguish from minimal breast cancer by histologic examination. In this study, the cumulative risk of breast cancer was approximately 4‐5% at 30 months and 9% at 48 months.