You question is missing a very important piece of information: What makes you think that past illness is something that'll scare off employers? In other words, what happened, and how did that affect you?
Keep that a secret unless you absolutely have to tell anyone. Insurance companies will impose a huge fee on any employer trying to hire you. This type of discrimination is one reason there are laws against what kinds of questions can and can't be asked in interviews.
Do NOT mention cancer to any potential employer unless you have to. Cancer doesn't just "go away". Any survivor will be on drugs for years and the threat of relapse is always there. In the eyes of anyone who is providing you with health insurance, it immediately makes you a liability.
No health insurance will cover anything for anyone who entered the scheme not disclosing a past treatment for cancer. Health insurance concerns do not go away (quite the opposite) by not disclosing cancer.
Disclose it when they ask for past medical history, then, not at a job interview. At that point, they've already hired you, and this becomes an annoying health insurance hassle and not a reason to not hire you. Why stack the deck against yourself?
You have to disclose it at some point, but it might be more prudent to disclose it as part of the health-insurance registration process after being hired.
Yes, but disclosing it in the resume/CV is way to early. You are basically asking potential employers to pass on you before you have a chance to show how valuable you are.
I don't think anyone will consider me unreliable, but for someone going through a stack of applications it's something that sticks out for the wrong reasons.
Plus, an application can be seen by a lot of people and you don't want to start a new job being THAT guy. I don't mind people knowing, but I like to have it on my terms if possible.