So, my Nana had lung cancer and she just recently passed away from it because they could not find her a new lungs for a transplant. Signs aren't typically noticeable or seem severe until you get tested and realize you have lung cancer. Some signs would be a new cough that doesn't go away and maybe even have a very heavy chest, shortness of breath, or coughing up blood sputum (spit or phlegm) A lot of the "symptoms" could be similar to a cold or even asthma. I would say if you don't have asthma or asthma history it would be good to go to the doctor to get it checked out. Like I said they are all very similar to a cold or something like that but should be checked out if continuous.
I hope this helps :)