Systemic inflammation score (SIS) to predict the effect of the postoperative adjuvant chemotherapy for patients with stage III colorectal cancer.
575 Background: Postoperative adjuvant chemotherapy (CTx) is a standardized treatment for patients with Stage III colorectal cancer (CRC). Since previous studies reported that the benefit of adjuvant CTx is estimated up to only 15% in Stage III patients, it is necessary to establish an appropriate patient selection for adjuvant CTx. Recently, systemic inflammation is reported to play a critical role in the progression of cancer and several studies demonstrate the impact of inflammation-based score, such as mGPS and SIS. There however is a lack of evidence for the influence of inflammation on patient requiring adjuvant CTx. The aim of this study is to evaluate the impact of SIS on patient selection of adjuvant CTx for Stage III CRC. Methods: Between 2004 and 2012 a total of 295 patients with Stage III CRC who underwent curative resection were included. The SIS was developed based on serum albumin and lymphocyte-to-monocyte ratio (LMR) levels (SIS = 0; albumin > 4.0 g/dl and LMR > 4.44, SIS = 1; albumin < 4.0 g/dl or LMR < 4.44, SIS = 2; albumin < 4.0 g/dl and LMR < 4.44). Primary endpoint was defined as disease free survival (DFS). DFS rates were compared using Kaplan-Meier curves and Prognostic factors were assessed by Cox proportional hazard model. Results: The median follow-up period was 5.99 years. 75.9% of patients received adjuvant CTx. The distribution of SIS was SIS = 0; 32.6 %, SIS = 1; 43.3 %, and SIS = 2; 24.1 %. In multivariate analysis for overall patients, SIS was not a significant prognostic factor. Subgroup analysis according to each SIS score demonstrated that adjuvant CTx significantly prevented postoperative recurrence just only in patients with SIS = 0 (5-year DFS rate; adjuvant CTx (+) 85.5 % vs. CTx (-) 33.7 %, p < 0.001 ). In Cox proportional hazard model, protective effect of adjuvant CTx decreased in proportion to the increase of SIS (HR of adjuvant CTx (95 % CI): SIS = 0; 0.187 (0.089-0.393), SIS = 1; 0.601 (0.311–1.162), SIS = 2; 0.747 (0.319–1.752)). Conclusions: The SIS can provide an appropriate patient selection for patients with stage III CRC who can benefit from adjuvant CTx. The results from this study might enhance precision medicine for adjuvant CTx for Stage III CRC.