Nottingham grade 2 breast cancer; is it a true prognostic category?

Abstract

BACKGROUND: Nottingham grade (NG) is a well-recognized prognostic factor derived by adding scores (1-3) given for three histological features of breast cancer (BC). NG is assigned according to the final score (NG1=score 3-5, NG2=score 6-7, NG3=score 8-9) where NG1 has the best and NG3 has the worst prognosis. OBJECTIVE: To assess whether the NG2 entails only patients with a similar prognosis. METHODS: Data were collected from all NG2 BC patients who had sought the services of our unit from 2006 to 2012. Grading was done by a single investigator. Patients were divided into two groups according to the score assigned in grading (6 and 7) and followed up with a mean follow-up time of 45 (SD=23) months. Clinico-pathological features were compared using chi-square test. Kaplan-Meier model with log-rank test was used for survival analysis. RESULTS: The study included 352 NG2 BC patients (score 6=195; score 7=157) with a mean age of 52 (SD=11) years. Majority of the patients with score 6 had ER/PR positive tumours (p=0.007 and 0.029) whereas score 7 patients had Her 2 positive tumours (p=0.002). There was a significant survival difference between the patients who had scores 6 and 7 (breast cancer specific survival p=0.007; recurrence free survival p=0.019). There was no survival difference between the patients with NG1 and score 6 and NG3 and score 7 (p>0.05). CONCLUSIONS: NG2 comprises two subsets of patients with a significant survival difference. Their prognosis is more in line with the preceding/subsequent grade than the same grade, probably due to the difference in ER/PR and Her 2 expression.