Abstract
<jats:p>Malignant neoplasms in older adults account for a substantial proportion of cancer cases worldwide, yet this population remains underrepresented in randomized clinical trials. The biological basis for this gap lies in age-associated remodeling of the immune system; however, its integrated molecular and clinical implications in oncology have long remained insufficiently characterized. This review summarizes current evidence on the molecular and cellular mechanisms of immunosenescence, inflammaging, and their impact on the tumor microenvironment. Literature was searched in PubMed/MEDLINE, ScienceDirect, Google Scholar, eLIBRARY.ru, and CyberLeninka for the period from 2020 to 2026; 82 sources were included in the final analysis. Available data suggest that immunosenescence and chronic low-grade inflammation contribute to the development of a stable immunosuppressive tumor microenvironment. These changes appear to vary across tumor types, including papillary thyroid cancer, glioblastoma, breast cancer, and gastrointestinal malignancies. Meta-analytic data indicate broadly comparable efficacy of immune checkpoint inhibitors in older and younger patients across most tumor types; however, age-related T-cell repertoire contraction, a higher risk of immune-related adverse events, and limited subgroup data restrict the generalizability of these findings.</jats:p>