Purpose

This phase II/III trial studies how well radiation therapy works when given together with cisplatin, docetaxel, cetuximab, and/or atezolizumab after surgery in treating patients with high-risk stage III-IV head and neck cancer the begins in the thin, flat cells (squamous cell). Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Drugs used in chemotherapy, such as cisplatin and docetaxel, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Cetuximab is a monoclonal antibody that may interfere with the ability of tumor cells to grow and spread. Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. The purpose of this study is to compare the usual treatment (radiation therapy with cisplatin chemotherapy) to using radiation therapy with docetaxel and cetuximab chemotherapy, and using the usual treatment plus an immunotherapy drug, atezolizumab.