Heavy usage of cannabis may facilitate the development of cancerous cells and tumors in the testes.

‚ÄčThis study evaluated the association between the use of cannabis and the prevalence of testicular cancer among Swedish men. Researchers followed 49,343 men conscripted into the Swedish military for a duration of 42 years, assessing their frequency of use of cannabis and occurrence of cancer of the testes. 

Researchers observed that the propensity to develop testicular cancer was high among heavy cannabis users (defined as individuals who used cannabis for more than 50 times in their lifetime). "The current study provides additional evidence to the limited prior literature suggesting cannabis use may contribute to the development of testicular cancer," the researchers concluded.