Histologic heterogeneity of triple negative breast cancer: A National Cancer Centre Database analysis

Triple negative breast cancer (TNBC) is an aggressive disease, but recent studies have identified heterogeneity in patient outcomes. However, the utility of histologic subtyping in TNBC has not yet been well-characterised. This study utilises data from the National Cancer Center Database (NCDB) to complete the largest series to date investigating the prognostic importance of histology within TNBC.

A total of 729,920 patients (pts) with invasive ductal carcinoma (IDC), metaplastic breast carcinoma (MBC), medullary breast carcinoma (MedBC), adenoid cystic carcinoma (ACC), invasive lobular carcinoma (ILC) or apocrine breast carcinoma (ABC) treated between 2004 and 2012 were identified in the NCDB. Of these, 89,222 pts with TNBC that received surgery were analysed. Kaplan-Meier analysis, log-rank testing and multivariate Cox proportional hazards regression were utilised with overall survival (OS) as the primary outcome.

MBC (74.1%), MedBC (60.6%), ACC (75.7%), ABC (50.1%) and ILC (1.8%) had significantly different proportions of triple negativity when compared to IDC (14.0%, p < 0.001). TNBC predicted an inferior OS in IDC (p < 0.001) and ILC (p < 0.001). Lumpectomy and radiation (RT) were more common in MedBC (51.7%) and ACC (51.5%) and less common in MBC (33.1%) and ILC (25.4%), when compared to IDC (42.5%, p < 0.001). TNBC patients with MBC (HR 1.39, p < 0.001), MedBC (HR 0.42, p < 0.001) and ACC (HR 0.32, p = 0.003) differed significantly in OS when compared to IDC.

Our results indicate that histologic heterogeneity in TNBC significantly informs patient outcomes and thus, has the potential to aid in the development of optimum personalised treatments.