Tubular differentiation in African breast cancer.

In an effort to determine numerical thresholds for histological breast cancer grading, we evaluated the fraction of fields with tubular differentiation (FTD) in Nigerian breast cancers (n=300). Analyses were based on Kaplan-Meier survival curves, and univariate and multivariate analyses by Cox's regression. The mean (SD) value of FTD in Nigeria, 16.7 (19.3)%, was much lower than reported in European breast cancer. Decreasing FTD was associated with increasing histological grades (p < 0.0001) and clinical stage (p = 0.0190). The most significant cut-point for FTD in predicting outcome was 15.0%. In univariate analysis, FTD 15% was a significant prognosticator in the whole material, in larger than 5cm tumours, among postmenopausal and premenopausal patients, and LN+ patients. After multivariate analysis with mitotic count, FTD was an independent prognosticator among tumours larger than 5cm, but not in other groups. We conclude that the rational grading of breast cancers need be optimised according to diagnostic and therapeutic environment. We propose FTD 15% as a cut-point to grade breast cancer in Nigerian material.