What is the percentage of lung tumors being benign vs cancerous?

<5%: Benign tumors of lung are rare many lung nodules are benign, because they are caused by an inflammatory agent.

Details matter: Many lung nodules are benign. This will depend on were you live. Lung nodules can be granulomas, infections, fungal infections, benign growths such as hamartomas, and finally cancerous. It is important to have either serial imaging or a biopsy if a lung nodule is found. There are currently guidelines for this that a pulmonary medicine specialist or thoracic surgeon should follow.