Intensity-Modulated Radiation Therapy & Nivolumab for Recurrent or Second Primary Head & Neck Squamous Cell Cancer

This phase II trial studies how well intensity-modulated radiotherapy and nivolumab work together in treating patients with head and neck squamous cell cancer that has come back. Intensity-modulation radiation therapy uses varying intensities of radiation beams to kill cancer cells and shrink tumors, thereby reducing the damage to nearby healthy tissue. Monoclonal antibodies, such as nivolumab, may interfere with the ability of tumor cells to grow and spread. Giving intensity-modulated radiation therapy and nivolumab may work better at treating head and neck squamous cell cancer.