Lindsay CR, et al. - By conducting a pooled analysis of individual patient data, researchers evaluated the clinical validity of the quantification of circulating tumour cell (CTC) for prognostication of individuals with advanced non-small cell lung cancer (NSCLC). For patients with advanced NSCLC who partook in CellSearch CTC studies from January 2003 to March 2017, 9 European NSCLC CTC centres were asked to provide reported/unreported pseudo-anonymised information. According to findings, 7 out of 9 eligible centres provided overall survival data for 550 patients with prognostic information. These data confirm CTCs in advanced NSCLC as an independent prognostic indicator of progression-free survival and overall survival and also show some proof of between-centre heterogeneity. In addition to full clinicopathological predictive models, CTC count improves prognostication.