Purpose: The aim of this retrospective, multicenter study was to develop a recurrence risk-scoring model in patients with curatively resected stage I lung adenocarcinoma (ADC).
Methods: Clinicopathologic and outcome data for a development cohort of 1,700 patients with pathologic stage I ADC from four institutions resected between January 2000 and December 2009 were evaluated. A phantom study was performed for correction of inter-institutional differences in positron emission tomography-standardized uptake value (PET-SUV). A nomogram for recurrence prediction was developed using Cox proportional hazards regression. This model was validated in a cohort of 460 patients in two other hospitals. The recurrence rate was 21.0 % for the development cohort and 22.1 % for the validation cohort.
Results: In multivariable analysis, three independent predictors for recurrence were identified: pathologic tumor size (hazard ratio [HR] 1.03, 95 % CI 1.017-1.048; p < 0.001), corrected PET-SUV (HR 1.08, 95 % CI 1.051-1.105; p < 0.001), and lymphovascular invasion (HR 1.65, 95 % CI 1.17-2.33; p = 0.004). The nomogram was made based on these factors and a calculated risk score was accorded to each patient. Kaplan-Meier analysis of the development cohort showed a 5-year recurrence-free survival (RFS) of 83 % (95 % CI 0.80-0.86) in low-risk patients and 59 % (95 % CI 0.54-0.66) in high-risk patients with the highest 30 percentile scores. The concordance index was 0.632 by external validation.
Conclusions: This recurrence risk-scoring model can be used to predict the RFS for pathologic stage I ADC patients using the above three easily measurable factors. High-risk patients need close follow-up and can be candidates for adjuvant chemotherapy.