Evaluation of maximum standardized uptake value at fluorine-18 fluorodeoxyglucose positron emission tomography as a complementary T factor in the eighth edition of lung cancer stage classification.

OBJECTIVES

This retrospective cohort study aimed to analyze the prognostic effect of maximum standardized uptake value (SUVmax) as a complementary T factor in addition to the clinical T category of the eighth-edition staging system for the prediction of disease-free survival (DFS) in patients with resected lung adenocarcinomas.

MATERIALS AND METHODS

A total of 572 patients (male:female = 235:337; median age, 64 years) with clinical stage I (T1-T2aN0M0) adenocarcinomas underwent preoperative fluorine-18 fluorodeoxyglucose positron emission tomography and subsequent lobectomy between 2009 and 2015. The prognostic values of SUVmax and T category [categorized SUVmax; T1 (SUVmax ≤2), T2 (2< SUVmax ≤7), and T3 (SUVmax >7)] in conjunction with the clinical T category were analyzed using a multivariable Cox regression and a likelihood-ratio test, respectively. The clinical T category was then upstaged or downstaged (cT) based on T. This new categorization system was evaluated using a Cox regression and then compared with the clinical T category.

RESULTS

Multivariable-adjusted Cox regression revealed that SUVmax and T were independent and significant predictors with the current clinical T category for DFS. Regarding SUVmax, the adjusted hazard ratio (HR) was 1.048 (95% CI: 1.009, 1.089; P = 0.017). Regarding T, the adjusted HRs were 2.365 (95% CI: 1.034, 5.406; P = 0.041) in T2 and 3.005 (95% CI: 1.258, 7.179; P = 0.013) in T3. The inclusion of the PET-derived factors substantially improved the model fit (P < 0.05). cT was a significant predictor of DFS, which improved the prognostic discrimination of lung adenocarcinomas.

CONCLUSION

SUVmax and T are independent prognostic factors after adjustment for the clinical T category. The T category could be used to adjust the clinical T category preoperatively.