Abstract
We often encounter the postoperative recurrence of lung cancer. It is generally diagnosed based on the clinical course and the results of imaging studies, such as computed tomography (CT) and positron emission tomography (PET). The organization diagnosis is often not done. We present the case of a patient who was treated for the postoperative recurrence of lung cancer that was later proven by biopsy to be a second lung cancer. It is possible that cases of a second cancer, like ours, are overlooked because they are incorrectly classified as postoperative recurrences of lung cancer based on the clinical course and imaging findings. However, when we encounter a case of suspected postoperative recurrence, we should also consider that it could be a second lung cancer.