FDG-PET/CT is an integral part of staging and radiation treatment planning for patients with stage III non-small cell lung cancer (NSCLC). In this study, we analysed the correlation between different PET parameters and survival in NSCLC patients treated with chemoradiotherapy (CRT).
Ninety-nine consecutive patients with NSCLC stage IIIA-B and good performance status, who underwent FDG-PET-CT before the start of CRT were analysed. Maximum standardized uptake value of primary tumor (SUVmax_PT) and range between the two most distant PET-positive (SUV≥3) lymph nodes in two directions (cranio-caudal and transversal) were analysed for their correlation with patient survival. The cranio-caudal distance was defined as A- and the transversal as B-line. The area under the ROC curve (AUC) as well as the cut-off SUVmax, A- and B-lines were calculated.
Median survival for the entire cohort was 20.8 months (95% CI: 15.3-26.3). Patients with SUVmax_PT ≥ 8 had poor overall survival (OS) (19 vs. 40 months in patients with SUVmax ≥ 8 and <8, p < 0.0001). A-line was not associated with OS, whereas B-line < 3.7 cm improved OS significantly (30 vs. 16 months in patients with B-line < 3.7 and ≥3.7cm, p = 0.001). The sum of A- and B-lines with the cut-off at 6.7cm correlated with overall survival significantly (29 vs. 18 months in patients with sum < 6.7 and ≥6.7cm, p = 0.04). The PET-CT score was generated on the basis of PET parameters correlated with OS in univariate analysis. The patients were divided into 4 subgroups. The low-risk subgroup (0 points) included patients with SUVmax_PT< 8, B-line < 3.7 cm and the sum of A- and B-lines < 6.7 cm (n = 20, 21.3%). Twenty-eight patients (29.5%) had 1 point (intermediate risk), 20 (21.3%) had 2 points (high) and 26 patients (27.7%) had 3 points (very high risk). Median OS in terms of low/intermediate/high and very high risk subgroups was 40 (95% CI: 0-83)/27 (95% CI: 15-39)/26 (95% CI: 15-37) and 14 months (95% CI: 13-14), (p = 0.0001).
A new PET-CT score was developed for patients with inoperable stage III NSCLC treated with definitive CRT. Initial SUVmax_PT < 8, B-line < 3.7 cm and PET-CT score were predictors of patient long-term outcome.
Clinical trial identification
Legal entity responsible for the study
Has not received any funding.
All authors have declared no conflicts of interest.