The main purpose of this study is to determine the safety, feasibility, and utility of intranasal (NAS) ketamine in persistent uncontrolled cancer related pain. In this prospective clinical trial the researchers will investigate the use of NAS ketamine in patients with pain related to cancer or cancer treatment. The researchers plan to enroll at least 15 patients meeting inclusion/exclusion criteria, to achieve a minimum of 10 patients who complete the study. Participants will be recruited from the supportive oncology clinic, oncology clinics, the pain clinic and Acute Pain Service at Emory. Participants will be asked to return to the Phase I unit of the Winship Cancer Building C for a total of 5 study visits, each two to five days apart. During these visits participants will complete questionnaires, have blood samples drawn and will have study medication administered to them in escalating doses. For safety monitoring participants will be contacted by telephone 14 days after the last dose of medication administered.