 The purpose of this research study is to learn about the effectiveness of using lower-intensity radiation and chemotherapy to treat human papillomavirus HPV associated low-risk oropharyngeal andor unknown primary squamous cell carcinomas of the head and neck. The cure rate for this type of cancer is estimated to be high, 90. The standard treatment for this cancer is 7 weeks of radiation with 3 high doses of cisplatin. Sometimes surgery is performed afterwards. This standard regimen causes a lot of side effects and long term complications. This study is evaluating whether a lower dose of radiation and chemotherapy may provide a similar cure rate as the longer, more intensive standard regimen. Patients in this study will receive 1 less week of radiation and a lower weekly dose of chemotherapy. 