Vitamin D Receptor rs731236 Polymorphism Modulates Cancer Cachexia Susceptibility and Overall Survival: A Real-World Study on Context-Dependent Vitamin D Signalling

Cancer-associated cachexia (CAC) is a complex metabolic syndrome characterised by progressive skeletal muscle loss, systemic inflammation, reduced treatment tolerance, and poor survival. Marked interindividual variability in CAC susceptibility suggests that host genetic factors may contribute to its development. Vitamin D plays an important role in muscle metabolism and inflammatory control through activation of the vitamin D receptor (VDR). VDR signalling influences myogenesis, mitochondrial function, insulin-like growth factor pathways, and pro-inflammatory cytokine expression, all of which are implicated in CAC pathogenesis. Hence, VDR variants, including the rs731236 (A>G) polymorphism, which modifies receptor activity, may affect CAC pathogenesis. Thus, this study investigated the association between the polymorphism and susceptibility to CAC as well as patient survival in a cohort of 140 adult cancer patients. Briefly, the rs731236 GG genotype was significantly associated with a lower prevalence of CAC across disease diagnostic approaches (chi-square tests, p < 0.05). Furthermore, GG genotype carriers demonstrated significantly improved survival compared with carriers of AA/AG genotypes (Log-rank and Tarone–Ware tests, p < 0.05). In summary, these findings suggest that the rs731236 polymorphism influences both susceptibility to CAC and survival outcomes in patients with cancer, further supporting a clinically relevant role for vitamin D signalling in supportive oncology care.