The Incidence of Malignant Non-Carcinomas of the Female Breast

Abstract

Objective: Demographic and tumor characteristics of all malignant non-carcinomas of the breast, including the lymphomas and myelomas, are the focus of this investigation.

Methods: Twenty-six US population-based registries identified 363,801 newly diagnosed malignant breast cancers among women during the time period 1994–1998. Of these, 4625 (1.3%) were reported simply as cancer, NOS; 357,775 (98.3%) were of epithelial origin (carcinomas or adenocarcinomas); and the remaining 1401 (0.4%) were non-epithelial in origin. All but nine of the non-epithelial breast cancers were some form of soft tissue sarcoma.

Results: The most common non-epithelial cancer was malignant phyllodes tumor, which accounted for 61% of these diagnoses. In addition to the 363,801 malignant cancers classified to the breast, another 613 tumors arose in the breast but were classified as myelomas or lymphomas; two as solitary myelomas, two as Hodgkin lymphoma and the remaining 609 as non-Hodgkin lymphoma.

Principal conclusions: The median age of females with a non-epithelial cancer (53) was 10 years younger than that of women with an epithelial cancer. The age-adjusted incidence rate per 100,000 females was 0.51 for non-epithelial cancers compared to 127.05 for epithelial cancers. Adding the myelomas and lymphomas, which are traditionally included with the hematopoietic cancers, to the incidence rates for breast cancer would increase the rate by less than 0.2 per 100,000.