Wu 2002.

Methods	Randomised controlled trial (1989 to 1995)
Participants	Individuals with pathologically confirmed NSCLC, cTNM stage I‐IIIA, age <71 Patients with stage IIIB and IV cancer after re‐staging from resection were excluded after randomisation as were those with incomplete resection and cancer other than NSCLC (total exclusions =61)
Interventions	Intervention group: lung resection plus systematic nodal dissection. Control group: Lung resection plus mediastinal lymph node sampling (hilar lymph node dissection, mediastinotomy & nodes of stations 1‐9 were explored, nodes of station 7 were routinely removed)
Outcomes	Surgical mortality. Overall survival (5 years). Proportion of participants experiencing tumour recurrence.
Notes	C‐factor staging C4 (after thoracotomy) Pathological stages were classified using the 1997 UICC revisions of the international system for staging lung cancer (Mountain 1997)
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Information not reported. After contacting study authors, sequence generation was reclassified as adequate (computer generated)
Allocation concealment?	Low risk	Information not reported. After contacting study authors, concealment of allocation was reclassified as adequate
Blinding? All outcomes	Unclear risk	None described
Incomplete outcome data addressed? All outcomes	Low risk	Description of withdrawals and losses to follow up were adequate (There were six cases lost to follow‐up and the rate of lost to follow‐up was 1.88%)

NSCLC = non‐small cell lung cancer 
 FEV1= Forced expiratory volume in 1 second; FVC = Forced vital capicity; MMEFR= maximum midexpiratory flow rate; MVV= maximum voluntary ventilation 
 SS = systematic sampling 
 CMLND = complete mediastinal lymph node dissection