Which is the better pathological prognostic factor, the Nottingham histological grade or the Japanese nuclear grade? A large scale study with a long-term follow-up

Background: We compared the Nottingham histological grade (H-grade) and the Japanese nuclear grade (N-grade) to select the better prognostic factor for breast cancers. Methods: The series included 1786 patients with breast cancers with the exception of non-invasive and stage 4 cancers. They were classified according to the H- and N-grade. We analyzed their survival curves and also performed multivariate Cox regression analyses. Results: According to the H-grade classification, 476 cases were grade 1, 647 cases were grade 2 and 663 cases were grade 3. According to the N-grade, 381 cases were grade 1, 215 cases were grade 2, and 1129 cases were grade 3. In the survival curves of those cases with lymph node metastases (N(+)) and recurrent cases, there were statistically significant differences in different categories of the H-grades, but not in the N-grades. The survival curves of all the cases and those cases without lymph node metastases (N(-)) always exhibited statistically significant differences. According to the 2003 St Gallen consensus, the N(-) group was classified as a minimal risk and an average risk groups. Both H- and N-grade exhibited statistically significant differences between the minimal risk and the average risk groups in the disease-free survival. The multivariate analyses proved that the H-grade was a statistically significant prognostic factor in all the cases and N(+) group, but the N-grade was not significant in any of the studies. Conclusions: The H-grade is clearly proved to be a more significant prognostic factor for wider stage cases than the N-grade.