Highly unusual... ...But not unheard of. There are a select few reports of fetuses who developed exceedingly rare lung tumors during gestation. Practically speaking, the overwhelming majority of lung cancers occur in adults and have genetic, environmental, and other causes, many of which only present themselves much later in life.
Unheard of. Developmental abnormalities can occur in any organ, but lung cancer, as we know it, is an acquired malady caused by alterations of many normal genes...Smoking is the biggest "alterer". However, we may inherit genetic predispositon or susceptible genes that can lead to lung cancer later in life. Lung masses in the new born occur, but it is not lung cancer.