Primary prognostic factors in invasive breast cancer with special reference to ductal carcinoma and histologic malignancy grade.

Background: In a study of 2290 cases of invasive breast cancer in Malmö, the prognostic value of histologic typing and axillary nodal status was examined. Two periods were studied: Period 1, 1961-1970, and Period 2, 1981-1988.

Methods: All primarily unilateral invasive breast cancers were included in the study and classified according to the histologic classification proposed by Linell et al. and Linell and Ljungberg (the Linell-Ljungberg classification), which includes a histologic grading of ductal carcinoma based on content of tubular structures. From Period 1, the tumors were reclassified. In Period 2, the Linell-Ljungberg classification was used as a clinical routine. Median follow-up in Period 1 was 23 years, and in Period 2, 5 years. Survival was calculated in relation to histologic type and axillary nodal status.

Results: The Linell-Ljungberg classification divides invasive ductal carcinoma (IDC) into two groups of approximately equal size: IDC of comedo type, 40% of total; and IDC of tubuloductal type, 30% of total. There was a significantly better survival rate in the tubuloductal group than in the comedo group. In a multivariate analysis, this difference was shown to be independent of axillary nodal status and tumor size. By combining histologic classification with axillary nodal status, one group of patients could be identified containing 90% of patients dying from breast cancer within 5 years of diagnosis and another group with less than 10% risk of dying from breast cancer within 5 years.

Conclusions: Valuable prognostic information can be obtained in a clinical setting from routinely obtained primary prognostic factors in breast cancer: pTNM stage, histologic type, and histologic malignancy grade. This information should be considered the baseline in the clinical evaluation of other more elaborate prognostic factors.