Swollen fingers cannot be a precursor to lung cancer. It may be due to allergic reaction, infectious lesions, immune disease or pestle finger. 1. Allergic reaction: When contact with substances that cause skin allergy leads to finger allergy, the local blood vessels of the finger will dilate, and the increase in permeability will lead to fluid exudation and swelling of the finger. 2. Infectious lesions: when the finger is infected due to trauma or nail ingrowth, the inflammatory exudate from the local soft tissue will lead to finger swelling. 3. Rheumatoid arthritis: when suffering from rheumatoid arthritis, the inflammation usually affects the small joints such as fingers, and the inflammation of the joints will lead to finger swelling. 4. Pestle finger: Cyanosis congenital heart disease, bronchopulmonary cancer, bronchiectasis, idiopathic fibrosis, etc. may also lead to hyperplasia and thickening of the ends of fingers or toes. Therefore, when patients have finger swelling, they should go to the local regular hospital for timely consultation, to clarify the cause of the disease and timely treatment.