An elderly former or current smoker with lung infiltrates (as seen on x-ray) along with a cough and purulent sputum (with or without fever) should be assumed to have lung cancer until proved otherwise. Other potential lung cancer symptoms besides chronic cough would be weakness, fatigue and pneumonia-like symptoms.
In the elderly, lung cancer usually manifests at a less advanced stage, and treatment, therefore, is usually more successful.
merck.com/mkgr/mmg/sec10/ch81…
Get a chest x-ray done if you suspect lung cancer.
good luck
Signs you can see obviously are wheezing/shortness of breath and clubbed fingers.