Association of circulating tumour cells with early relapse and ¹⁸F-fluorodeoxyglucose positron emission tomography uptake in resected non-small-cell lung cancers

OBJECTIVES: More than 20% of lung cancer patients develop a recurrence, even after curative resection. We hypothesized that relapse may arise from the dissemination of circulating tumour cells (CTCs). This study evaluates the significance of CTC detection as regards the recurrence of non-small-cell lung cancer (NSCLC) in surgically resected patients. Secondly, we investigated the association between CTCs and the uptake of ¹⁸F-fluorodeoxyglucose (FDG) by the primary tumour on a positron emission tomographic (PET) scan. METHODS: In this single-centre prospective study, blood samples for analysis of CTCs were obtained from 102 patients with Stage I-IIIA NSCLC both before (CTC1) and 1 month after (CTC2) radical resection. CTCs were isolated using immunomagnetic techniques. The presence of CTCs was correlated with the maximum standardized uptake value (SUVmax) measured on preoperative FDG PET/computed tomographic scans. Recurrence free survival (RFS) analysis was performed. RESULTS: CTCs were detected in 39.2% of patients before and in 27.5% 1 month after the operation. The presence of CTCs after the operation was significantly correlated with SUVmax on PET scans, pathological stage and surgical approach. Only SUVmax was an independent predictor for the presence of CTC2 on multivariate analysis. Postoperative CTCs were significantly correlated with a shorter RFS (P = 0.005). In multivariate analysis, the presence of CTC2 was associated with RFS, independent of disease staging. CONCLUSIONS: Detection of CTCs 1 month after radical resection might be a useful marker to predict early recurrence in Stage I-III NSCLC. The SUVmax value of the primary tumour on preoperative PET scans was associated with the presence of CTC 1 month after the operation.