Cannabidiol for Pain Relief of Patients With End-stage mCRPC

Inclusion Criteria: * Patients diagnosed with mCRPC as documented by increasing PSA despite optimally attempted treatment, and no other therapeutic options. * Treatment-resistance or ineligible to standardized cancer therapy, incl. medical and surgical castration, chemotherapy, and super hormone treatment. * Minimum 3 months since radiation therapy, if part of treatment. * Perception of pain * Daily use of Morphine (ATC: N02AA01) (10mgx2) in relief of pain. Exclusion Criteria: * Perception of worst pain \<4.0 on the NRS within the last week prior to baseline visit70. (Inclusion if: three days with highest pain intensity have an average of ≥4.0 and/or three days where pain intensity is at least 4.0). * Pattern of short duration of response to all previous treatment regimens (\<6 months) clinically assessed by the investigator. * Eastern Cooperative Oncology Group (ECOG) performance status \>3 (scale 0-5). * Change in regular use of conventional pain medication within two weeks prior to baseline visit. * A history of substance use disorder. * Functional liver insufficiency with an alanine transaminase (ALT) \>2X ULN and/or bilirubin \>2X ULN assessed by a blood sample taken at screening. * Renal failure with an estimated glomerular filtration rate (eGFR) \< 30mL/min/1,73m2 assessed by a blood sample taken at screening. * Known heart failure - New York Heart Association III - IV (scale I-IV)71. * Known severe chronic obstructive lung disease (Forced Expiratory Volume in the first second (FEV1) \<50%)72. * Use of THC-containing cannabis products measured by a urine sample at screening. * Any chronic or acute systemic medical condition that, in the opinion of the investigator, may pose a risk to the safety of the patient or may interfere with compliance or the assessment of efficacy in this trial. * Hypersensitivity to the active substance * Not capable of giving informed consent. * Not capable of understanding, write or read Danish.