A new study suggests that previous use of cannabis is associated with a lower risk of certain genitourinary cancers.
Prior cannabis use was associated with a reduced risk of renal cell carcinoma (RCC) and bladder cancer in women and a reduced risk of prostate cancer in men.
These findings were published in Cancer Medicine.
The study included 151,945 people with information on cannabis use from the UK Biobank. Of this cohort, 33,449 people said they had ever used cannabis.
In a multivariable analysis of the entire cohort, previous cannabis use was associated with a lower risk for RCC (hazard ratio [HR], 0.61; 95% CI, 0.40-0.93; P =.021) and prostate cancer (HR, 0.83; 95% CI, 0.74-0.94; P =.003).
However, there was no significant association between prior cannabis use and testicular cancer (HR, 0.85; 95% CI, 0.37-1.97; P =.853) or bladder cancer (HR, 0.77; 95% CI, 0.58-1.02; P =.071) in the overall cohort.
When they analyzed patients by sex, the researchers found different associations between men and women.
In women, prior cannabis use was significantly associated with a decreased risk of RCC (HR, 0.42, 95% CI, 0.19-0.94; P =.034) and bladder cancer (HR, 0.43; 95% CI, 0.21-0.86; P =.018). However, these associations were not observed in men.
The researchers suggested that this finding might be explained by hormonal differences between men and women or differences in how cannabinoid metabolism and receptors function.
The researchers also found that current cannabis use was associated with an increased risk for RCC (HR, 129.50; 95% CI, 40.97-409.34; P <.001), bladder cancer (HR, 112.22; 95% CI, 49.74-253.22; P <.001), and prostate cancer (HR, 43.31; 95% CI, 29.59-63.38; P <.001). Data for testicular cancer were not provided.
The researchers noted, however, that some of the current cannabis use might be the result of a cancer diagnosis, so it is “inappropriate” to interpret current cannabis use as a risk factor.
“Due to the limited information in the UKB database, we were not able to distinguish cannabis use because of cancers from the current use of cannabis [not due to a cancer diagnosis],” the researchers wrote.
Huang J, Huang D, Ruan X, et al. Association between cannabis use with urological cancers: A population-based cohort study and a mendelian randomization study in the UK biobank. Cancer Medicine. Published online August 17, 2022. doi:10.1002/cam4.5132