Cancer and aging: complex associations and therapeutic targets.

The incidence of cancer increases markedly with aging, and the two processes share underlying molecular mechanisms. In the context of global population aging and rising cancer incidence, nine convergent hallmark axes have been identified: genomic instability, epigenetic drift, inflammation-immunity imbalance, microbiome dysbiosis, metabolic reprogramming, telomere attrition, stem cell exhaustion, cellular senescence, and autophagy dysfunction. These hallmarks constitute an integrated regulatory network that operates synergistically, antagonistically, or through bidirectional feedback across molecular, cellular, and microenvironmental levels. Genomic instability, epigenetic remodeling, chronic inflammation, microbiome dysbiosis, and metabolic reprogramming in aging often act synergistically to promote tumorigenesis, whereas telomere attrition and stem cell exhaustion primarily exert antagonistic, tumor-suppressive effects. Cellular senescence and autophagy dysfunction display context-dependent dual roles. Importantly, this network framework has direct relevance to cancer therapeutics. Although chemotherapy, radiotherapy, and immunotherapy effectively suppress tumor progression, they frequently induce therapy-induced senescence, characterized by cell-cycle arrest and a senescence-associated secretory phenotype, thereby accelerating functional decline and increasing long-term toxicities in older patients. The proposed "synergistic-antagonistic-dual" framework linking aging and cancer not only helps explain the disproportionate cancer burden in older adults but also supports a "one drug, two targets" therapeutic paradigm. Targeting these shared pathways has delayed aging phenotypes and suppressed tumorigenesis in preclinical studies and early clinical trials, highlighting the potential of integrated interventions that concurrently address aging and cancer.