The rising incidence of age-related brain pathologies, including brain malignancy, underscores an urgent need to understand the mechanistic interplay between aging and tumorigenesis. Historically viewed as distinct entities, brain tumors and neurodegenerative disorders are now recognized to share key biological processes, such as cellular senescence, chronic inflammation, and metabolic dysregulation. In this review, we deconstruct the existing knowledge at the intersection of cancer neuroscience and aging biology; and propose that age-related alterations in neuronal function, such as the accumulation of senescent cells, ion channel dysregulation, and neurotransmitter imbalance, are not inert background features but as active mediators of tumor progression and treatment resistance. We summarize the aged neural microenvironment, marked by a proinflammatory senescence-associated secretory phenotype (SASP) and blood-brain barrier dysfunction, underlies permissive soil for malignancy. Moreover, we highlight the emerging concept that tumors can induce a pathological aging phenotype in surrounding neurons, which in turn potentiates the observed cognitive deterioration. By framing brain tumors as products of a dysfunctional aging ecosystem, we propose therapeutic strategies that target convergent aging mechanisms through senolysis, metabolic reprogramming, and neurotransmitter modulation, may simultaneously achieve tumor control and preserve cognitive function. This integrated perspective opens new avenues for repurposing neuroactive drugs and designing interventions that address the sophisticated biology of between aging brain and maligancy.

Aging remains the primary risk factor for malignancy, driven primarily by the progressive decline of the immune system known as immunosenescence. Natural killer (NK) cells serve as the critical effectors of tumor immunosurveillance, yet their anti-tumor efficacy is compromised during biological aging. This review delineates the multifaceted mechanisms of NK cell immunosenescence including phenotypic subset redistribution, receptor signaling dysregulation, and metabolic biogenesis failure driven by mitochondrial impairment alongside telomere attrition and p16 p21 mediated cell cycle arrest. These cell intrinsic defects interact with the suppressive aging microenvironment to create a self-reinforcing vicious cycle that facilitates tumor escape in the elderly population. Breaking this cycle necessitates a multi-dimensional therapeutic framework that integrates cellular rejuvenation via induced pluripotent stem cell (iPSC) derived chimeric antigen receptor (CAR) NK cells with niche remodeling using senolytics or bone marrow rejuvenation. Ultimately targeting the biological hallmarks of NK cell immunosenescence represents a significant frontier in geriatric oncology offering the potential to resuscitate anti-tumor immunity for the burgeoning elderly population.

Homologous recombination (HR) is a high-fidelity DNA repair pathway that preserves genome stability through the accurate repair of DNA double-strand breaks. RAD51 is the central recombinase of HR and catalyzes the key processes of homology search and strand invasion through the formation of nucleoprotein filaments on single-stranded DNA. The assembly, stability, and disassembly of RAD51 filaments are tightly regulated by a complex network of mediators, cofactors, and anti-recombinases, ensuring efficient DNA repair while preventing aberrant recombination. Beyond its canonical role in HR, RAD51 also contributes to replication fork protection and replication stress responses. Dysregulation of RAD51 activity can lead to genome instability, cancer development, hereditary disorders, and cellular senescence. Conversely, elevated RAD51 expression frequently promotes therapeutic resistance in tumors. In this review, we summarize the molecular mechanisms of RAD51-mediated HR repair, discuss the regulatory pathways that control RAD51 activity and dynamics, examine its roles in genome stability and human disease, and highlight recent advances in therapeutic strategies targeting RAD51 and the HR pathway. Understanding the multifaceted functions of RAD51 will facilitate the development of more effective DNA repair-directed cancer therapies.