The purpose of this study was to investigate the predictive value of histological grade in triple negative breast cancer (TNBC). We retrospectively analyzed 305 TNBC patient charts from 2004-2017 at Windsor Regional Cancer Center with triple negative defined as estrogen (ER), progesterone (PR), and HER-2 negative. The significance of grade with respect to demographic and treatment variables as well as patient outcomes was determined. 

There were found to be 10, 45, and 250 patients with tumor grades 1, 2, 3, respectively. The overall survival rates were 90.12%, 64.4%, and 77.2%, for patients with grade 1, 2 and 3 tumors respectively (p=0.019). Overall relapse rates were 70%, 55.6%, and 75.6%, respectively for patients with tumor grades 1, 2, and 3 (p=0.04) Comparing between grade 2 and grade 3, we determined that patients with grade 2 tumors had a 5.5-fold increased risk of death (HR=5.513; 95% CI 1.2-25.6) and shorter time to relapse (HR=1.9; 95% CI 1.1-3.2) at five years from time of diagnosis. In this retrospective review, grade was shown to have positive predictive value in determining relapse. This finding has the potential to impact patients and their clinicians, and as well, suggests a unique focus on this patient group in future research is recommended.