Cachexia index as a prognostic marker in gastrointestinal cancer with nomogram development and external validation

The cachexia index (CXI) integrates skeletal muscle, albumin and systemic inflammation. We assessed its prognostic value and developed survival nomograms in 822 patients with gastrointestinal cancer, with external validation in 3,101 patients. CXI thresholds were 90.80 for men and 106.52 for women. Low CXI was associated with poorer disease-free survival (DFS; follow-up-averaged adjusted hazard ratio 1.84, 95% confidence interval 1.45–2.33) and overall survival (OS; 1.94, 1.38–2.72). Five-year DFS was 50.4% versus 70.9%, and OS was 70.4% versus 87.0%, in the low- and higher-CXI groups, respectively. The nomograms incorporated CXI, weight loss, tumor site and TNM stage. Bootstrap-corrected C-indices were 0.738 for DFS and 0.799 for OS; external C-indices were 0.681 and 0.639. External areas under the curve at two, three and five years were 0.706, 0.689 and 0.692 for DFS and 0.829, 0.707 and 0.638 for OS. The association persisted after age and sex adjustment and exclusion of second primary malignancies. These findings support CXI as a prognostic marker and a component of survival risk stratification in surgically treated gastrointestinal cancer.