Studies were included if they involved patients with histologically confirmed esophageal cancer (both squamous cell carcinoma and adenocarcinoma), reported the CALLY index calculated as (CRP/Albumin)/Lymphocyte count, investigated the association between CALLY index and overall survival, provided sufficient data to calculate risk ratio (RR) with 95% confidence intervals (CI) or data that allowed for their calculation, were cohort studies (prospective or retrospective), or were case-control studies. The gene discussed is CRP; the disease is esophageal cancer.