BackgroundGrowing evidence indicates that inflammation contributes to cancer progression, and several inflammatory markers have been reported to be associated with the clinical outcomes in patients with various types of cancer. Recently, the advanced lung cancer inflammation index (ALI) has been developed as a prognostic marker in patients with lung cancer. The difference between the ALI and the inflammatory markers reported in the previous studies is that the ALI contains not only indices related to inflammation but also the body mass index (BMI), which was reported to correlate with the sarcopenic status. The aim of this study was to evaluate the prognostic significance of the ALI in patients with unresectable metastatic colorectal cancer.MethodsWe retrospectively reviewed a database of 159 patients who underwent combination chemotherapy for unresectable metastatic colorectal cancer between 2008 and 2016. The BMI was calculated by dividing the weight by height squared. The neutrophil-to-lymphocyte ratio (NLR) was calculated from a blood sample by dividing the absolute neutrophil count by the absolute lymphocyte count. The ALI was defined as follows: ALI=BMI × serum albumin concentration/NLR.ResultsThe overall survival rate was significantly worse in the low-ALI group than in the high-ALI group (p < 0.0001). Furthermore, the ALI was an independent prognostic factor for the overall survival (hazard ratio: 2.773, 95% confidence interval: 1.773–4.335, p < 0.001).ConclusionsA newly developed prognostic marker, the ALI, was found to be a novel prognostic marker in patients with unresectable metastatic colorectal cancer as well as in patients with lung cancer.