Potential Therapeutic Synergy of High-Dose Vitamin C and Nicotinamide as Adjunctive Therapy in an Elderly Patient With Extensive-Stage Small-Cell Lung Cancer: A Case Report.

We report the case of a 78-year-old male with extensive-stage small-cell lung cancer (ES-SCLC) involving the brain, bone, and adrenal gland at diagnosis, who exhibited a near-complete thoracic radiologic response following platinum-etoposide-atezolizumab therapy with consolidative thoracic and whole-brain radiotherapy. In addition to standard chemoimmunotherapy, the patient self-administered high-dose oral vitamin C (3g/day) and nicotinamide (3g/day) continuously throughout treatment, raising the possibility that metabolic adjunctive therapy may have contributed to the depth of response. Initial CT and fluoro-ethyl-tyrosine (FET) fusion imaging showed a large mediastinal mass, which nearly disappeared after five cycles of treatment. This case highlights that substantial therapeutic responses are achievable even in elderly patients with extensive metastatic disease and suggests that adjunctive metabolic modulation with high-dose vitamin supplementation may warrant further investigation as a potential enhancer of response to chemoimmunotherapy.