Lipid in invasive cancer of the breast.

Abstract

Intracytoplasmic lipid was demonstrated with oil red O in apparently viable tumor cells of 65 of 87 consecutive examples of invasive mammary cancer. In almost a third of these it was assessed as being moderate (2+) or marked (3+). Statistical analyses revealed a significantly greater likelihood that tumors with moderate or marked lipid also would have squamous metaplasia, low nuclear (most anaplastic) and high histologic (most malignant) grades, and slight, loose stroma. Although the samples were regarded as small, there also was the suggestion that these degrees of lipid were associated with short-term treatment failure. Except for the occasional focus of tumor cells with optically clear cytoplasm in a few of the lipid-containing cancers, features of so-called “lipid-rich” mammary cancer were lacking. Indeed, all of the tumors had characteristics of well-recognized histopathologic types of mammary cancer. It is concluded that some of the purported characteristics of the so-called “lipid-rich” cancer, particularly its more aggressive clinical behavior, are related to its lipid content per se rather than any other one feature or constellation of features. A similar view is expressed regarding the so-called “clear cell” cancers of the breast, which may or may not be synonymous with lipid-rich cancer. The degree of intracytoplasmic lipid in cancers of the breast appears to represent an important and useful histopathologic discriminant.