Abstract Background: Recently, the preoperative immune-nutritional status has been reported to correlate with the long-term survival in colorectal cancer (CRC) patients. Markers of the immune-nutritional status, such as the serum albumin concentration and prognostic nutritional index (PNI) were reported to have prognostic value. However, there have been no reports on the relationship between the controlling nutritional status (CONUT) score and the clinical outcome after curative surgery for CRC. We herein evaluated the prognostic significance of the CONUT score in patients with CRC, and compared the accuracy of the CONUT score and the PNI as a predictor of survival. Materials and methods: We retrospectively reviewed a database of 204 patients who underwent curative surgery for Stage II/III CRC between 2004 and 2009. Patients were divided into two groups according to the CONUT score and the PNI. Result: The low-CONUT group (N = 150) had two or fewer points, while the high-CONUT group (N = 54) had a score of three points or more. The low-PNI group (N = 27) had a PNI < 40, while the high-PNI group (N = 177) had a PNI of 40 or more. The five-year relapse-free survival (RFS) rate was 73.0% in the low-CONUT group and 53.6% in the high-CONUT group, which was significantly different (p = 0.0018). The five-year RFS was 51.5% in the low-PNI group and 70.4% in the high-PNI group, there was a significant difference between the low PNI group and the high PNI group (p = 0.0162). In a univariate analysis of the postoperative survival based on the clinicopathological factors, the sex, age, lymphatic vessel invasion, venous invasion, lymph node metastasis, preoperative CA19-9 level, the CONUT score and the PNI were associated with the RFS. A multivariate analysis showed that sex (Odds ratio (OR) = 2.012, 95%CI; 1.135-3.685, p = 0.0164) and the preoperative CA19-9 (OR = 2.194,95%CI; 1.054-4.271, p = 0.0364) were independently associated with the RFS. The five-year cancer-specific survival (CSS) rate was significantly higher at 92.7% in the low-CONUT group than that of 81.0% in the high-CONUT group (p = 0.0016). The five-year CSS was 71.2% in the low PNI group and 92.3% in the high PNI group, which was also significantly different (p = 0.0155). In a univariate analysis for the CSS, lymph node metastasis, the preoperative CA19-9 level, the CONUT score and the PNI were significantly associated with the CSS. A multivariate analysis showed that lymph node metastasis (OR = 4.080, 95%CI; 1.476-13.089, p = 0.0097) and the CONUT score (OR = 3.661, 95%CI;1.084-11.234, p = 0.0376) were independently associated with the CSS. Conclusion: This study suggested that the CONUT score is a strong independent predictor of the survival among CRC patients. The CONUT score is a more sensitive prognostic factor than the PNI. Citation Format: Yasuhito Iseki, Masatsune Shibutani, Kiyoshi Maeda, Hisashi Nagahara, Hiroshi Ohtani, Tetsuro Ikeya, Kenji Sugano, Sadaaki Yamazoe, Katsinobu Sakurai, Kenjiro Kimura, Takahiro Toyokawa, Ryosuke Amano, Naoshi Kubo, Hiroaki Tanaka, Kazuya Muguruma, Masaichi Ohira, Kosei Hirakawa. Impact of the preoperative Controlling Nutritional Status (CONUT) score on the clinical outcome after curative surgery for colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3418. doi:10.1158/1538-7445.AM2015-3418