William G. Rule, M.D., is a radiation oncologist at Mayo Clinic Comprehensive Cancer Center in Phoenix, Arizona. Dr. Rule treats colon cancer, esophageal cancer, stomach cancer, anal cancer, cholangiocarcinoma, pancreatic cancer, neuroendocrine tumors, liver cancer, leukemia, lymphoma and multiple myeloma. He is an expert in proton beam therapy, intraoperative radiation therapy, intensity-modulated radiation therapy, total skin electron beam therapy and stereotactic body radiotherapy. Dr. Rule focuses on the best treatment for your unique cancer while optimizing your quality of life. He speaks English and Spanish. Mayo Clinic is the #1 hospital in Arizona, according to the U.S. News & World Report, and the Cancer Center continually ranks among the top hospitals in the U.S. for Cancer. Mayo Clinic Comprehensive Cancer Center is a National Cancer Institute (NCI)-designated comprehensive cancer center.