A high cannabinoid CB₁ receptor immunoreactivity is associated with disease severity and outcome in prostate cancer

CB₁IR in a core of non-malignant tissue obtained at transurethral resection from a 76-year-old patient. The magnification used was 40×.

CB₁IR in prostate cancer tumour tissue obtained at transurethral resection. Panel A: tissue from a 74-year-old patient (magnification 20×). The tumour size was 10% of the resected tissue, and was given a Gleason score of 6. The numbers in the figure indicate the CB₁IR scores for the individual cells. Panel B: left three images: tumour tissue cores with CB₁IR scores of 1, 2 and 3, respectively. The far right image is a non-malignant tissue core from the same patient who scored 3. Panel C: left column, replicate cores of tumour tissue from a 69-year-old patient, tumour size 95%, Gleason score 8. All five cores were given a CB₁IR score of 3. In the right column, replicate cores from a 71-year-old patient (tumour size 25%, Gleason score 8) are shown. The CB₁IR scores ranged from 3 (top) to 1.5 (bottom), giving a median value of 2. Note that the brightness of the images was adjusted digitally to give similar levels of the background, and that the bottom core in panel B left column was photographed on a different occasion to the others.

Kaplan–Meier plots for the fraction survival of patients followed with active expectancy with tumour CB₁IR scores of <2 or ⩾2. Panel A: all patients (n=269); B: patients with %Ca scores>20; C: patients with Gleason scores 6 or 7; and D: patients with Gleason scores of 6. The hatches on the lines indicate the censored data (i.e. cases other than death due to prostate cancer). The 15-year probabilities of event-free survival for CB₁IR scores of <2 or ⩾2, respectively, were A: 78±7% compared to 50±5%; B: 60±13% compared to 21±6%; C: 85±9% compared to 44±9%; and D: 100% compared to 40±13%.