This phase III trial compares the effect of the combination of fluorouracil, oxaliplatin, and leucovorin calcium (FOLFOX) or capecitabine and oxaliplatin (CAPOX) followed by limited surgery with transanal endoscopic surgery (TES) versus chemoradiation followed by TES for the treatment of early stage rectal cancer. The usual approach for patients who are not in a study is surgery to remove the rectum or treatment with chemotherapy and radiation therapy, followed by surgery. Fluorouracil stops cells from making deoxyribonucleic acid (DNA) and it may kill tumor cells. Leucovorin is in a class of medications called folic acid analogs. When used with fluorouracil, it enhances the effects of this chemotherapy drug. Oxaliplatin is in a class of medications called platinum-containing antineoplastic agents. It damages the cells DNA and may kill cancer cells. CAPOX is a combination of two drugs (capecitabine and oxaliplatin) and used as standard chemotherapy in treatment of rectal cancer. CAPOX works by damaging the DNA in tumor cells, and may cause the cells to stop growing and die. Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill tumor cells and shrink tumors. This study will help researchers find out if chemotherapy with FOLFOX or CAPOX prior to surgery works better, the same, or worse than the usual approach and improves the quality of life in patients with early rectal cancer.

This phase III trial compares pembrolizumab with radiation therapy to pembrolizumab without radiation therapy (standard therapy) given after pembrolizumab plus chemotherapy for the treatment of patients with squamous cell carcinoma of the head and neck that has spread from where it first started (primary site) to other places in the body (metastatic). Pembrolizumab is a type of immunotherapy that stimulates the body's immune system to fight cancer cells. Pembrolizumab targets and blocks a protein called PD-1 on the surface of certain immune cells called T-cells. Blocking PD-1 triggers the T-cells to find and kill cancer cells. Radiation therapy uses high-powered rays to kill cancer cells. Giving radiation with pembrolizumab may be more effective at treating patients with metastatic head and neck cancer than the standard therapy of giving pembrolizumab alone.