BACKGROUND: Clinical staging of NSCLC helps determine prognosis and management of patients; few data exist on accuracy of clinical staging and the impact on treatment and survival of patients. We assessed whether participant or trial characteristics were associated with clinical staging accuracy as well as impact on survival. METHODS: We used individual participant data from RCTs, supplied for a meta-analysis of pre-operative chemotherapy (+/- radiotherapy) versus surgery alone (+/- radiotherapy) in NSCLC. We assessed agreement between clinical TNM (cTNM) stage at randomization and pathological TNM (pTNM) stage, for participants in the control group. RESULTS: Results are based on 698 patients who received surgery alone (+/- radiotherapy) with data for cTNM and pTNM stage. 46% of cases were cTNM stage I, 23% cTNM stage II and 31% cTNM stage IIIa. cTNM stage disagreed with pTNM stage in 48% of cases, with 34% clinically understaged and 14% clinically over-staged. Agreement was not associated with age (p=0.12), gender (p=0.62), histology (p=0.82), staging method (p=0.32) or year of randomisation (p=0.98). Poorer survival in understaged patients was explained by the underlying pTNM stage. Clinical staging failed to detect T4 disease in 10% of cases and misclassified nodal disease in 38%. CONCLUSIONS: This study demonstrates suboptimal agreement between clinical and pathological staging. Discrepancies between clinical and pathological T and N-staging could have led to different treatment decisions in 10% and 38% of cases respectively. There is therefore a need for further research into improving staging accuracy for patients with stage I-IIIa NSCLC
