We wish to clarify a comment made in the editorial regarding our systematic review.¹ In an otherwise insightful piece, Holty and Gould² considerably played down the importance of complete mediastinal lymph node dissection (CMLND) in reducing locoregional and distant relapse after lung cancer resection because of what they called “stage migration”. They are correct that about 10% of participants were excluded from analysis after randomisation and minor breaches of intention-to-treat principles occurred in two of the three trials analysed. These, however, should not be confused with the Will Rogers phenomenon,³ where more accurate staging results in better apparent survival for each stage subgroup. This is the problem with every retrospective or stage-matched series comparing CMLND with systematic sampling, but is avoided in trials with patients prospectively randomised and analysed on an intention-to-treat basis. We emphasise that we did not perform any stage-based subanalyses, but compared …