You need to read your own source. It does not say Cannabis causes cancer. Like I said if you had actual evidence of this claim it would be a world's first. Also you don't need to smoke cannabis to reap it's benefits.

Whether cannabis can cause cancer is not a simple question to answer. We know from very clear evidence that tobacco causes cancer. But we are still learning about the effects of cannabis and whether it has the same effects as tobacco. There are a number of factors that suggest that cannabis could cause cancer