A benign lung tumor is an abnormal growth of tissue that serves no purpose and is found not to be cancerous. Benign lung tumors may grow from many different structures in the lung. Determining whether a nodule is a benign tumor or an early stage of cancer is very important.he first thing that may come to mind is a dreaded word: cancer. In many cases, though, a lung nodule turns out to be benign. This means that it isn't cancer. A hard part is waiting and not knowing.