Early Detection of Cancer; Lung Neoplasms/prevention & control; Mass Screening; Smoking Cessation; Smoking/therapy; Tobacco Use Cessation Devices; Tobacco Use Disorder/drug therapy; Aged; Benzazepines/therapeutic use; Bupropion/administration & dosage; Dopamine Uptake Inhibitors/administration & dosage; Early Detection of Cancer/methods; Female; Follow-Up Studies; Humans; Italy/epidemiology; Lung Neoplasms/diagnostic imaging; Lung Neoplasms/epidemiology; Lung Neoplasms/etiology; Male; Mass Screening/methods; Middle Aged; Nicotinic Agonists/therapeutic use; Pilot Projects; Propensity Score; Prospective Studies; Quinoxalines/therapeutic use; Severity of Illness Index; Smoking/adverse effects; Smoking/epidemiology; Smoking Cessation/methods; Tobacco Use Cessation Devices/adverse effects; Tobacco Use Disorder/epidemiology; Tobacco Use Disorder/etiology; Tomography, X-Ray Computed; Treatment Outcome; Varenicline