Seen on CT can be characterized based on several factors in their appearance. If it looks benign, they can be left alone. Intermediate lesions may warrant a follow-up CT. Lesions that are more suspicious for cancer may be biopsied under CT guidance, or may warrant a PET-CT scan.

Not all masses are cancerous, however, the majority of cancers in smokers are cancerous. Your doctor probably wants to do a screen CT to exclude lesions not seen on a routine chest x-ray. He is being cautious which is good