Whenever I tell people I am a lung cancer survivor, they ask me how I knew I had it. I tell them I had a wheeze, just a little wheeze...and that I had never had a wheeze before.
But it wasn't until I got a chest X-ray that it could be diagnosed. And I waited probably 6 months from the time I had the wheeze until I got the chest X-ray. I might have been able to reduce my cancer from a stage III to a stage I if I had been more proactive.
I am pretty sure my cancer came from radon exposure, because I found out later the house I've been living in for 15 years had a very high level (and I had quit smoking over 30 years ago). I encourage people to get a chest X-ray and a radon test kit...both cheap, both important.