Validity of St Gallen risk categories in prognostication of breast cancer patients in Southern Sri Lanka

Background: Although, there are many developments in the field of management, breast cancer is still the commonest cause of cancer related deaths in women in Sri Lanka. This emphasizes the need for validation of treatment protocols that are used in Sri Lanka for managing breast cancers. There are no published papers on treatment and survival of breast cancer patients in Sri Lanka. Hence this study was designed to determine the validity of St Gallen risk categories based on the survival outcomes of breast cancer patients in Southern Sri Lanka. Method: This retro-prospective study included all female breast cancer patients who had sought the immunohistochemistry services of our unit from May 2006 to December 2012. Patients who had neo-adjuvant chemotherapy were excluded. Patients were stratified according to the St Gallen risk categories; low-risk (LR), intermediate-risk (IR) and high-risk (HR), which is used in deciding on the adjuvant treatment. IR category was subdivided based on presence/absence of 1-3 positive-nodes (absent-IR1, present-IR2) and HR on the number of positive-nodes(1-3 lymph nodes; HR1,>3 lymph nodes; HR2). Kaplan-Meier and Cox-regression models were used in the survival analysis. Results: This study included 713breast cancer patients (LR-2%, IR1-45%, IR2-10%, HR1-13%, HR2-30%). Five year breast cancer specific survival (BCSS) wasLR-100%, IR-91%, HR-66% and the recurrence free survival (RFS) was LR-85%, IR-84%, HR-65%. BCSS and RFS curves were significantly different between the three risk categories (p < 0.001). No survival difference was evident between the IR1 and IR2 (BCSS-p = 0.232, RFS-p = 0.118). HR1 and HR2 had a distinctly different BCSS (p = 0.033) with no difference in RFS (p = 0.190). Conclusion: This study validates the St Gallen risk categorization of female breast cancer patients in our setting. However, the HR includes two subsets of patients with a distinct difference in BCSS.