I found out about my cancer by accident. I had a gall bladder scan, and part of my lower lung showed up and they thought it might have a nodule or an artifact. I came back for a chest ct a few months later, and a mass was found in my upper left lung.
Looking back on it, I did have one symptom that could suggest a lung problem. I would several times a day have a spontaneous gasp and my pulmonologist said that was my brain telling my lungs, not enough air. Get more. So I would gasp. I doubt that this is an official symptom though.
Don M