Can molecular subtyping replace axillary nodal status as prognostic marker in breast cancer?

Subtypes are an established prognostic factor of BC in western population but its significance in Indian BC patients has not been evaluated. Thus this study provides an insight into the prognostic significance of molecular classification and its effect on the survival of BC patients in Eastern India. In this hospital based study 242 BC patients attending a Comprehensive Breast Service Clinic of a reputed institute in Eastern India and having IDC were studied over a period of 7 years (January 2007 to October 2013). Nonluminal HER-2-positive and Triple negative tumors were associated with advanced stage of disease, metastatic lymph nodes and NPI ≥5.4, whereas Luminal 1 and Luminal 2 tumors were associated with early stage, uninvolved lymph nodes and NPI <5.4. Better survival was observed for the patients with Luminal 1 [OS = 57.1 % (n = 36)] and Luminal 2 [OS = 60.0 % (n = 6)], compared to Triple negative [OS = 33.6 % (n = 38)] and nonluminal HER-2-positive tumors [OS = 32.1 % (n = 18)]. This study provided some idea about the pattern of BC on the basis of classification by molecular profiling. Our study indicated that Triple negative and nonluminal HER-2-positive tumors have reduced DFS and OS compared with luminal 1 and 2 subtypes. In our patients, Triple negative and nonluminal HER-2-positive tumors were associated with established unfavorable prognostic indicators and this reflects the data in the western literature. The results suggest that the molecular subtypes are an independent prognostic and predictive marker in Indian BC patients. Whether or not molecular subtyping of breast cancer can replace axillary lymph nodes as the standard in prognosis remains to be seen, but if molecular subtyping can provide more information than the axilla about the prognosis and treatment option, it may well be the future of prognostication.