Taha Koray ŞAHİN, Onur BAŞ, Gözde KAVGACI, Naciye GÜDÜK, Fırat ŞİRVAN, Serkan AKIN, Zafer ARIK, Neyran KERTMEN, Ömer DİZDAR, Mustafa ERMAN, Şuayib YALÇIN, Sercan AKSOY, Burak Yasin AKTAŞ, Deniz Can GÜVEN
Journal of Oncological Sciences - 2026;12(1):1-8
Objective: Vitamin D exerts pleiotropic effects on tumor biology and immune regulation, including modulation of T-cell function and antigen presentation. Preclinical evidence suggests that optimal vitamin D status may enhance immune checkpoint inhibitor (ICI) efficacy; however, data are limited among ICI-treated patients. We aimed to evaluate the prognostic significance of baseline serum 25(OH)D levels in patients receiving ICIs. Material and Methods: A retrospective cohort of 244 patients with advanced solid tumors treated with ICI. Baseline serum 25(OH)D concentrations, obtained within 30 days prior to ICI initiation, were categorized as sufficient (>20 ng/mL), insufficient (12-20 ng/mL), or deficient (<12 ng/mL). Results: The median age of the patients was 63 years; 65.2% were male. The most common tumor types were non-small cell lung cancer (32.8%), renal cell carcinoma (18.9%), and melanoma (14.3%). Vitamin D status was sufficient in 36.5%, insufficient in 34.8%, and deficient in 28.7% of patients. In multivariable analysis, vitamin D deficiency independently predicted shorter overall survival (OS) [hazard ratio (HR): 2.264, 95% confidence interval (CI): 1.553-3.300; p<0.001] compared with the vitamin D-sufficient group. Both vitamin D insufficiency (HR: 1.494; 95% CI: 1.067-2.092; p=0.019) and vitamin D deficiency (HR: 2.0; 95% CI: 1.411-2.833; p<0.001) were independently associated with inferior progression-free survival (PFS). Conclusion: Baseline vitamin D deficiency is an independent adverse prognostic factor for OS and PFS in ICI-treated patients. Integrating vitamin D assessment into pretreatment evaluation may facilitate risk stratification and inform supportive care strategies, warranting prospective validation.
