Prognostic value of necrosis in Nigerian breast cancer

Three hundred cases of invasive breast carcinoma from Nigeria with mean follow-up time of 25.9 months were subjected to evaluation of the extent of necrosis. The prognostic significance of necrosis, and association with other prognostic factors were evaluated.

Necrosis was stratified as follows: mild (tumour necrosis evident in 0-29% of x 40 microscope fields of the neoplasm), moderate (30-59%), and extensive (over 60%).

These were observed in 193 (64.3%), 93 (31.0) and 14 (4.7%) carcinomas, respectively. Necrosis was more prominent than reported for Europe or other Western countries to date. The extent of necrosis had a positive correlation with the age (r=0.21, p=0.0002), tumour size (r=0.40, p=<0.0001), clinical stage (r=0.25, p=<0.0001), histological grade (r=0.42, p=<0.0001), standardized mitotic index (SMI) (r=0.38, p=<0.0001), mitotic activity index (MAI) (r=0.34, p=<0.0001), mean nuclear area (MNA) (r=0.33, p=<0.0001), and a negative but highly significant correlation with the fraction of fields with tubular differentiation (FTD) (r= -0.28, p=<0.0001). However, no significant correlation was observed between the extent of necrosis and apoptosis (r=0.05, p=0.3939). There was a statistically significant difference in the extent of necrosis in the tumours of postmenopausal and premenopausal patients. Lymph node-positive tumours had more necrosis than lymph node-negative tumours. The statistically optimal prognostic threshold for the extent of necrosis in the whole Nigerian material was 30% (p=0.0007). The extent of necrosis also proved useful in prognostication among the premenopausal patients (p=0.0004). In a multivariate Cox's regression analysis involving necrosis, SMI (cutpoint 92), and tumour size (cutpoint at 5cm), necrosis had no independent prognostic value.

The use of necrosis in the prognostic evaluation of African breast cancers is advocated in view of the good reproducibility and relatively simple estimation with the conventional light microscope, especially in cases of which other prognostic data is not available. The association of necrosis with outcome clearly suggests that necrosis is associated with more advanced and more progressed disease in these neoplasms.