STAMP: Surgically Treated Adjuvant Merkel cell carcinoma with Pembrolizumab, a Phase III TrialCarcinoma

This study is being done to answer the following question: Can we lower the chance of your cancer growing back by adding a study drug after your surgery? We are doing this study because we want to find out if this approach is better or worse than the usual approach for your Merkel Cell Carcinoma. The usual approach is defined as care most people get after surgery to remove the cancer.