Cannabis Oil and Radiation Therapy for the Management of Pain

Inclusion Criteria: 1. Ability to consent to the study-specific written consent form, in English or French; 2. Adult patients, male and female between the ages of 18 and 75 (inclusively); 3. Patients with confirmed diagnosis of metastatic carcinoma of the prostate, lung or breast; 1. No limitation with respect to number of metastases (bone and visceral); 2. Location of metastases limited to exclude any brain metastases 4. Patients experiencing an average weekly pain intensity score of 4 or higher on a 11 points NRS and requiring palliative RT; 5. KPS of equal or higher than 60; 6. Subject agreed to follow the protocol; 7. Patients who are referred to receive RT and are non-regular users of cannabis in any form (three times per week or more) and are willing to abstain for 1 week prior and during the study; 8. Patients receiving opioids and other concomitant pain medications must have a stable dose for the last 15 days; 9. Normal cognitive status according to MiniCog; 10. Normal liver function (defined as aspartate aminotransferase 10-40 U/L and alanine aminotransferase 7-56 U/L) 11. Normal renal function (defined as serum creatinine level \<133 µmol/L and Estimated Glomerular Filtration Rate (eGFR) equal or higher than 60) 12. Negative result on βhuman chorionic gonadotropin pregnancy test (if applicable) 13. A female volunteer must meet one of the following criteria: 1. If of childbearing potential - agrees to use one of the accepted contraceptive regimens from at least 28 days prior to the first drug administration, during the study and for at least 60 days after the last dose. 2. If of non-childbearing potential - should be surgically sterile or in a menopausal state 14. A male volunteer with sexual partners who are pregnant, possibly pregnant, or who could become pregnant must be surgically sterile or agrees to use one of the accepted contraceptive regimens from first drug administration until 3 months after the last drug administration. Exclusion Criteria: 1. Patients who are unable to consent or to comply with the instructions of the study; 2. Patients suffering primarily from pain not related to cancer; 3. KPS of \< 60; 4. Previous serious adverse event or hypersensitivity to cannabis or cannabinoids; 5. Presence of significant cardiac disease (history of unstable ischemic heart disease, heart failure, severe and uncontrolled hypertension) that, in the opinion of the investigator, would put the patient at risk of a clinically significant arrhythmia or myocardial infarction; 6. Current substance use disorder according to the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM 5); 7. Life-time history of dependence on cannabis or diagnosis of cannabis use disorder (CUD) according to the DSM 5; 8. Life-time history of DSM 5 schizophrenia, bipolar disorder, or previous psychosis with or intolerance to cannabinoids; 9. Current suicidal ideation according to the Columbia-Suicide Severity Rating Scale (C-SSRS); 10. Pregnant, breast-feeding or female patients of child-bearing potential and male patients whose partner is of child-bearing potential, unless willing to ensure that they or their partner use effective contraception; 11. Hepatic impairment (aspartate aminotransferase more than three times normal) or renal function impairment (serum creatinine level \>133 µmol/L. 12. Cognitive impairment according to MiniCog; 13. Current use of cannabis in any form more than 3 times per week or use of cannabinoid-based medications within 7 days of study entry and refusal to abstain for the duration of the study; 14. Positive blood test for cannabinoids at screening or positive urine screening for other potential abuse substances (e.g. alcohol, cocaine, amphetamines and methamphetamines, unprescribed opioids); 15. Participation in another clinical trial within 30 days of screening visit