There's nothing wrong w/ a shadow line, but a scar--that's in another and bigger league. Transplants leave scars like all other surgery. I'd even say do Hairclub before surgery, but shave first--it will grow back. As you can see from my current avatar, I've got a pronounced shadow and it troubled me for a while. Now it's my sign to the world that I'm in control.
Re: Cancer, do like a guy on this forum said about 14 months ago when I raised that concern after shaving, "Tell them, 'No, Libra (or enter your sign) actually, what's your sign?" It works unless you're born in July1!