The authors of this study set out to determine the association of cannabis (marijuana) use and tobacco use with bladder cancer. The health records of 84,170 participants from the California Men’s Health Study were evaluated.
41% reported cannabis use, 57% reported tobacco use, 27% reported using both, and 29% used neither. The men were followed over an 11-year period. It was found that cannabis use only was associated with a 45% reduction in bladder cancer incidence. Tobacco only users had the highest rate of bladder cancer incidence, followed by those who combined both.
While this does not prove causality, the association does exist that cannabis users developed less bladder cancer. Future studies may answer why. After all, marijuana does have a strong anti-inflammatory effect on the body.