Estimation of Recurrence Risk After Normal (18)F-FDG PET/CT in Nonsmall-Cell Lung Cancer

The authors aimed to assess the risk of recurrence in patients with nonsmall-cell lung cancer after surgery with no evidence of disease (NED) demonstrated on (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). A total of 140 subjects with adenocarcinoma or squamous cell carcinoma of the lung were included in this study. Patients had FDG PET/CT scans within a year after surgery between January 2007 and December 2014. Patients with PET/CT scans with NED were included. Following an NED PET/CT scan, recurrence or metastasis was found in 14 patients (10.0%), and deaths in 4 (2.9%) during a median follow-up of 636 days. Although the rates of recurrence or metastasis were very low, the risk for recurrence continuously increased after 600 days up to 0.03%. The risk was higher in patients with positive margin at surgery, lymphovascular invasion, N2 stage, and TNM stage III/IV. In conclusion, according to the smoothed hazard functions, there was a very low risk of recurrence until 600 days after normal (18)F-FDG PET scans. The risk was higher in patients with positive margin at surgery, lymphovascular invasion, N2 stage, and TNM stage III/IV.