@jmah My father, too, was diagnosed at the age of 71. He smoked for 58 years. He was in for a routine checkup, but when his doctor came in, he said, “Tell me how long you’ve been coughing up blood.” My father hadn’t told anyone but my mother at that time. They did x-rays and found a spot on his lung.
Looking back, prior to his diagnosis, he started slowing down a bit and had a pain in his shoulder, but nothing that really seemed like lung cancer, other than his gradual loss of lung capacity over the 58 years of smoking.
Shortly after the lung cancer was fixed up (by removing half of one lung), he had an aortic aneurysm diagnosed and fixed, and most recently, a quadruple bypass. Smoking is one of the risk factors for all of his problems.