I heard that marjhana causes testicular cancer in young males. Now I worry so much about my relative what can be done?

Marijuana is Safe. Hi; this myth that you have heard is not true. There is very little science that shows that marijuana is in any way physically harmful. Now that does not mean that one with an addiction or an addictive personality may have mental health troubles and have unwanted consequences when using this drug. But, from a medical setting mj does not cause testicular cancer.
Credible? Periodically theories are put forth about cannabis causing cancer. To my knowledge these reports have not been substantiated by unequivocal studies. In 1940's, leading medical authorities told us that "reefers" caused "madness". Certainly that science has entered trashbin of history. Most discussions about cannabis are infused with strong personal opinions of all shades and varieties.