Condition: Carcinoma, Squamous Cell

This is a randomized, double-blind, study that compares pembrolizumab (MK-3475) with placebo given as adjuvant therapy in participants with high-risk locally advanced cutaneous squamous cell carcinoma (LA cSCC) that have undergone surgery with curative intent in combination with radiotherapy. The primary hypothesis is that pembrolizumab is superior to placebo in increasing recurrence free survival (RFS).