Immunoscore as a parameter predicting time to recurrence and disease-free survival in T4N0 stage II colon cancer patients.

4105 Background: Risk assessment is particularly important to decide when to propose an adjuvant treatment for Stage II Colon Cancer (CC) patients. However, the current tumor risk features are imperfect and additional risk factors are needed to guide treatment decisions. The consensus Immunoscore is an alternative and powerful approach that could be used in the T4N0 Stage II colon cancer population. Immunoscore is an in vitro diagnostic test that predicts the risk of relapse in patients with CC by measuring the host immune response at the tumor site. Methods: From the international Immunoscore consortium study (n = 2681) (Pagès et al. The Lancet 2018), a subgroup analysis was performed on T4N0 Stage II colon cancer patients (n = 208). Results: In stage II T4N0, Int+Hi Immunoscore represented 65.4% of the population and low-Immunoscore only 34.6%. T4N0 patients with Int+Hi Immunoscore presented a significantly prolonged survival for TTR compared to low Immunoscore patients (5 years recurrence rate Int+Hi: 84.6% (78.3-91.5), Lo: 46.3% (35.1-61); unadjusted HR [Int+Hi vs Lo] = 0.21; (95% CI 0.11-0.4); P\u3c 0.0001), representing a restricted mean survival time (RMST) difference of 80.9 months (95% CI 51.1-110.6) (P\u3c 0.0001). The DFS was significantly different between Int+Hi and Low Immunoscore (5 years recurrence rate Int+Hi: 70.5% (95% CI 62.7-79.1), Lo: 38.5% (95% CI 28.2-52.5); unadjusted HR [Int+Hi vs Lo] = 0.31; (95% CI 0.19-0.49); P\u3c 0.0001). Using restricted mean survival time (RMST) a significant (P\u3c 0.0001) difference of 60.4 months (95% CI 32.6-88.1) was observed between the 2 groups Importantly, Cox multivariate analysis in Stage II T4N0 colon cancer patients, revealed that Immunoscore was the only remaining significant parameter (HR [Int+Hi vs Lo] = 0.15; (95% CI 0.05-0.46); P= 0.0009). In contrast, all other parameters, gender, sidedness, mucinous, grade, T-stage, VELIPI, MSI were not significant in multivariate analysis. Finally, Immunoscore showed the highest relative contribution to predict relapse (76.2% chi2 relative contribution), stronger than all the other parameters, MSI (16.1%), Grade (5%), sidedness (2%), gender (2%), VELIPI (1%). Conclusions: Immunoscore is the most powerful parameter to predict the risk in T4N0 population, and could be a good tool for adjuvant treatment decision in Stage II patients