It is common for patients to have pulmonary nodules detected 0n CT. These are often nonspecific, which means that it can be difficult to determine the cause. For patients without history of cancer, follow-up is based on Fleischner Society guidelines, which takes into account nodule size and appearance, as well as if patient is low risk or high risk for lung cancer (e.g., smoking history). For patients with history of cancer, as in your case, Fleischner Society guidelines do not apply. Instead, follow-up is based on the specific clinical situation and at the discretion of ordering provider.