Cannabis Oil and Radiation Therapy for the Management of Pain

This is a 6-week randomized, double-blind, placebo-controlled, parallel group design trial followed by an open-label extension phase of 12 weeks, to evaluate tolerability of medical cannabis oil to reduce chronic pain intensity. Consecutive adult patients between the ages of 18 and 75, male and female, with cancer pain, with an average weekly pain intensity score greater than 4 on the 11 points Numerical Rate Scale (NRS), will be prospectively recruited and invited to participate in this trial. Informed consent will be obtained by a Research Assistant. After baseline documentation with standardized scales, patients will be randomized to one of two parallel groups: * Cannabis group: Delta-9 Tetrahydrocannabidiol (THC) /Cannabidiol (CBD) ratio 1:1 capsule * Placebo group: Placebo capsule * All patients will receive palliative RT to the symptomatic site. Patients will have a dose titration phase during the first week. The dose escalation will allow patients to adapt to the potential adverse effects (AEs) of the medical cannabis. Follow-up visits either in person or by phone will be at 1 week, 3 weeks and 6 weeks of treatment. At the end of the first phase of the study, patients who wish to participate in the open-label extension phase will have the option to continue in the same treatment regimen. For the placebo group, patients will have the option to receive the active treatment during the 12-week open-label phase if the study physician feels it may potentially provide benefits. Similarly, the dose will be titrated up in the placebo group who wants to receive the active drug in the extension program. The open-label phase is 12 weeks long. For this open-label extension phase the follow-up visits will be done after 4 weeks and 12 weeks of treatment.