Everything can causes cancer
Cancer is best known as a Radical cell(a cell that does not do anything good in the body and just feeds upon it. /logic), and yes they are the same as our cancers in the community and society.
Cancer is a product of excessiveness in our body, we can be very healthy and still create cancer, simply because inside the body there might be too much of "something".
Anyways, we are getting off-topic and this is about addiction, OP, in addictions there are two types:
1. Mental Addiction
2. Chemical Addiction
Though every kind of feeling is product by some "locally" produced chemical(particularly in the brain), from sad to happy, it's all due to an irregularity in the brain.
These can still be considered Mental Addictions(these are easier to overcome and even get rid off), Chemical(3rd Party) are basically meant to release those "locally" made chemicals in your brain, but, at an excessive amount this excessive amount is basically impossible to create by simple means(like masturbation, Video Games, etc.) .
I would say the main difference between Chemical and Mental addictions is... Withdraw, the common occurrence that happens to drug abusers, most are send into a state of lunacy and they may get chills, repulsion and such, a real sad view on an addicted person.