Quad-shot-immunotherapy: quad-shot radiotherapy with pembrolizumab for advanced/recurrent head and neck cancer.

Advanced and recurrent head and neck cancers are difficult to treat. Most patients receive systemic therapies, such as chemotherapy or immunotherapy, with modest rates of cancer control. We aim to test the effectiveness of an immunotherapy drug called pembrolizumab in combination with a type of low-dose radiation therapy called quad-shot. Patients will receive pembrolizumab every 3 weeks and will be treated with one to three low-dose radiation therapy courses targeted at their cancer in the head and neck approximately every 12 weeks. We plan to measure how well the cancer responds to treatment, how long this response lasts, how long patients survive and treatment side effects.