Can Prognostic Significance of Lymph Node Dissection Be Assessed by Randomized Clinical Trials in Patients with Lung Cancer?

The clinical significance of lymph node dissection in patients with lung cancer has been thought to lie in the confirmation of the accurate staging and the improvement of prognosis by better local control. The latter benefit, however, has not been scientifically demonstrated. Based on the data of National Cancer Center, we have estimated the feasibility of the clinical trial by comparing the prognoses of patients undergoing either systematic lymph node dissection or sampling alone. Under the condition of 5-year survival of the control arm (sampling alone) at 60% and hazard ratio at 0.9 (α = 0.05, 1-β = 0.80), 2,387 patients should be required for each treatment arm. Considering the acceptable mortality rate related to the lymph node dissection, which was already demonstrated in many previous reports, and very large number of patients necessary for this clinical trial, we think that this trial in an attempt to prove the survival advantage of lymph node dissection cannot be achieved with satisfactory quality, and is not always necessary at the present situation.