Journal of skin cancer
Oral Nicotinamide for the Secondary Prevention of Cutaneous Squamous Cell Carcinoma and Other Keratinocyte Carcinomas: A Systematic Review
By Guerra Jiménez AL, Ortegón Garciaherreros JC, Suárez Escobar LP and 2 others.
Abstract
Background
Oral nicotinamide has been proposed as a chemoprevention strategy to reduce new keratinocyte carcinomas in people with a history of skin cancer, but its effect may differ between immunocompetent patients and transplant recipients.
Objective
To evaluate the effectiveness and safety of oral nicotinamide for the secondary prevention of cutaneous squamous cell carcinoma and other keratinocyte carcinoma-related outcomes in adults with a history of skin cancer.
Methods
We conducted a systematic review following PRISMA 2020. We searched PubMed/MEDLINE, Embase, and LILACS through the Virtual Health Library from inception to May 30, 2026. We included comparative studies (randomized clinical trials and controlled nonrandomized studies) evaluating oral nicotinamide versus placebo, no treatment, usual care, or another preventive strategy. Risk of bias was assessed with RoB 2 for randomized trials and ROBINS-I for nonrandomized studies, and the certainty of evidence was assessed with GRADE. We performed a narrative synthesis and an exploratory random-effects meta-analysis of randomized trials when clinically appropriate; effect measures were rate ratios for randomized trials and hazard ratios for the observational cohort. Randomized and nonrandomized designs were not statistically pooled together.