Predictive value of Immunohistochemical 4 plus Clinical Treatment Score in determining risk of Loco Regional Recurrence in Early Breast Cancer. (#95)
Aim: Combined score obtained using Immunohistochemical (IHC) 4 score (based on estrogen and progesterone receptor status, human epidermal growth factor receptor 2 status and Ki-67 index) plus Clinical Treatment Score (CTS) (based on nodal status, tumor size, grade and age) is a very promising clinicopathological tool predicting risk of distant recurrence. Given that loco regional recurrence (LRR) is a significant predictor of the risk of distant recurrence we hypothesized that the combined score also predicts the risk of LRR which is the primary objective of this study. Methods: This is a prospective cohort study of women with early invasive breast cancer selected from the local database over a 13 year period. Eligible women had breast conserving surgery (BCS) for invasive breast cancer but no adjuvant radiation. If any of the ihc results were missing, tumor blocks were retrieved to perform the required tests. IHC4 score and CTS were calculated using appropriate formulae from the original study by Cuzick et al1 and both these were added to calculate the combined score. Results: Cox regression indicated a significant association between the combined score and the risk of LRR (p=0.03). When the cut-off points as in the original study1, were applied to the LRR outcome, the incidence of LRR was zero, 20 % and 33.3 % in the low, intermediate and high risk groups respectively (p=0.007). We analysed the contribution of margin status to the combined score as this was the only major pathological variable not included in the score. The Cox regression analysis demonstrated that combined score (p=0.02) and the ordinal measure of margins (p=0.03) were significant independent predictors of LRR. Conclusions: This is the first study of its kind. The combined score may be used to identify women at negligible risk of LRR in whom adjuvant radiotherapy can be omitted.