Large decreases in standardized uptake values after definitive radiation are associated with better survival of patients with locally advanced non-small cell lung cancer

We evaluated potential associations between maximum standardized uptake value (SUV _max) on ¹⁸F-FDG PET before and after radiation therapy (RT) and survival outcomes for patients with locally advanced non-small cell lung cancer. Methods: Patients with stage III non-small cell lung cancer (n = 49) who had undergone ¹⁸F-FDG PET at the M.D. Anderson Cancer Center both before and up to 3.5 mo after undergoing radiochemotherapy were studied; exclusion criteria were patients with a history of thoracic surgery, RT, or other cancer or those who had received a total radiation dose less than 60 Gy. We assessed associations between overall survival (OS) or disease-free survival (DFS) and post-RT SUV _max and the extent of decrease in SUV _max in the primary tumor (PT) and regional lymph nodes (LNs). SUV _max was assessed as a continuous variable by Cox proportional hazards regression analysis. Results: Univariate and multivariate analyses showed that having a high post-RT SUV _max (either PT or LNs) was associated with a higher risk of death (univariate analyses: hazard ratio [HR] for PT SUV _max, 1.27, P < 0.0001; HR for LN SUV _max, 1.32, P = 0.004) and disease recurrence (univariate analyses: HR for PT SUV _max, 1.16, P = 0.004; HR for LN SUV _max, 1.32, P = 0.001). Moreover, after definitive RT, the greater the decrease in SUV _max in the lesion that had the highest SUV _max at diagnosis, the longer the OS (HR, 0.06; P = 0.002), DFS (HR, 0.03; P = 0.001), local-regional control (HR, 0.04; P = 0.002), and distant metastasis-free survival (HR, 0.07; P = 0.028). Conclusion: The post-RT SUV _max in both the PT and the LNs was a predictor of survival - specifically, the higher the residual SUV _max after RT, the poorer the OS and DFS; and the greater the decrease in SUV _max in the lesion with the highest SUV _max at diagnosis, the longer the OS and DFS. This information should help to identify patients who are at high risk of recurrence and for whom additional treatments can be designed accordingly.