I've seen the devastation that addiction and cancer both cause. I've heard this comparison before and in my opinion they are 2 totally different things. I've lost family members to cancer. They WANTED to live, they WANTED to spend more time with their loved ones and see their kids grow up. They FOUGHT with everything they had until physically they couldn't fight anymore.
My AH has been blessed with great physical health and what does he do? He deliberately poisons himself with drugs. Nobody chooses to get cancer. The same can't be said for drug use. Yes, the drugs harm the body, the brain and they have horrible side effects. But I've never heard of anyone seeking to get another hit of cancer, or paying to actually get it. On the contrary, they try to do everything they can to get rid of it.