Purpose To figure out tumor markers changes in lung cancer (LC) patients after immunotherapy and their link with inflammation in the body. Methods From May 2017 to January 2021, taking 97 LC patients with elevated Programmed Cell Death Protein 1 and Programmed Cell Death Protein-ligand 1 was as the research objects. They were all given immunotherapy and assigned into the remission and the nonremission groups on the grounds of the tumor remission after 6 months of treatment, after comparison of tumor markers [carcinoembryonic antigen (CEA), squamous cell carcinoma-associated antigen (SCC-Ag), cytokeratin 19 fragment (CYFRA12-1), and neuron-specific enolase (NSE)] and inflammation indicators [interleukin-10 (IL-10), interleukin (IL-6), and tumor necrosis factor-α (TNF-α)] in the two. Results Tumor markers, IL-10, IL-6, and TNF-α in the remission after treatment were reduced vs. the nonremission (P < 0.05); SCC-Ag was positively linked with IL-10, IL-6, and TNF-α in the patients after treatment (P < 0.05); the AUC of the combined detection to assess the efficacy of LC immunotherapy was greater vs. the individual detection of indicators (P < 0.05). Conclusion Tumor markers and the inflammation state of the body in LC patients are memorably reduced after immunotherapy, and a correlation is presented between the two, which manifests evaluating value of the efficacy of immunotherapy.