I have ocd with hand washing but think i'm doing harm to my health if don't scrub off all the soap. can obsessive hand washing n soap cause cancer?

Not likely but it: will create skin conditions (making it raw, red, swollen, and prone to infections if broken). A dermatologist might help your skin but its your brain that is the problem. OCD is an anxiety disorder with underlying neurological conditions. Try a psychiatrist for meds and a psychologist for behave mgt. Here's a reference on anxiety: http://www.psychologyproductsandservices.com/page2.html