Background: It is unclear how comorbidities are associated with the stage of non-small cell lung cancer (NSCLC) at cancer diagnosis. We aimed to evaluate the association between Charlson Comorbidity Index (CCI) and TNM stage at diagnosis among a large sample of NSCLC patients. Methods: From the database of our institutional Cancer Center Cancer Registry, we found 2,510 patients with NSCLC who were diagnosed and treated at our institution from 2004 to 2014. The patients were enrolled based on the following inclusion criteria: 1) had undergone a baseline FDG PET/CT, 2) had no evidence of brain metastasis, and 3) did not have concurrent diagnosis or a history of other primary cancer. A total of 949 patients were enrolled and used for this retrospective study. 19 comorbidities at the baseline defined by the Charlson, et al., were used to determine the CCI. Overall survival (OS) was determined from the FDG PET date to the death from any cause. Other factors included age, gender, race, and smoking history, NSCLC clinical staging at diagnosis (7th edition). Multivariate regression analyses were performed to determine the association between the CCI and TNM stages, adjusting for age, gender, race and smoking history. Results: Among the 949 incident NSCLC patients, 429 (45%) were male, 452 (48%) were black, with a mean age of 67 (s.d. 11), and median survival of 24 months (interquartile range 10-55 months). The number of patients with TNM stage for IA, IB, IIA, IIB, IIIA, IIIB, and IV were 171 (18%), 103 (11%), 67 (7%), 40 (4%), 164 (17%), 107 (11%), and 297 (31%), respectively. Three hundred fifty-three (37%) patients had no comorbidity at the baseline, 251 (26%) patient with CCI of 1, 171 (18%) of patients with CCI of 2, and 99 (10%) with CCI of 3, and 75 (8%) patients with CCI of 4 or higher. Controlling for age, gender, race, and smoking history, the adjusted parameter estimate of CCI is -0.20 (95% CI: -0.30, -0.10, p = 0.01). Conclusions: Higher value of CCI is negatively associated with an advanced cancer stage at diagnosis, suggesting healthier adults being less likely to receive an early diagnosis of NSCLC.