Yes, zab, I agree that existing conditions can be bad. And they needn't be as devastating as lung cancer. I have a nuisance arthritis condition called Reiter's Syndrome. It makes my hands hurt (sometimes quite badly) and the balls of my feet. I occasionally get flares to the point of requiring NSAIDs to treat it. Once every 5 years, perhaps Prednisone.
As you may know, arthritis is one of the 3 A's that insurance companies don't want to touch since they think you are a great candidate for knee/hip replacement. I started a small software company in 1995 and tried desparately to get health insurance for the 18 months of my Cobra coverage (which cost me a bundle). Finally, I just threw up my hands and went back into the big corporate workforce to regain insurance. Like you, I couldn't even get a quote.