Optimal distance of malignant negative margin in excision of nonsmall cell lung cancer: a multicenter prospective study

Abstract Background Complete excision of nonsmall cell lung cancer is necessary during a limited resection procedure, as a malignant positive margin can lead to margin relapse. Because there is scant information available regarding the optimal size of a malignant negative margin, we conducted a multicenter, prospective study to more fully elucidate this area of concern. Methods Two hundred five pulmonary tumors (22 nonsmall cell lung cancers and 183 undiagnosed lesions) were excised, of which 118 nonsmall cell lung cancer lesions were analyzed. Malignant status was considered positive when either a cytologic or histologic technique revealed the margin to be malignant. Maximum tumor diameter (from 4 to 45 mm with an average of 15.3 mm), margin distance (from 0 to 25 mm with an average of 9.3 mm), tumor location, extent of stapling carried out, and performance of a thoracotomy were the variables. Results Seventy-two of the sample tissues (61%) were malignant negative. The negative group had smaller maximum tumor diameter, greater margin distance, lesions in more easily resectable regions, and more often required stapling only. Using a multivariate analysis, maximum tumor diameter and margin distance were found to be independent factors. The number of malignant negative margins was 7/7 (100%) when the margin distance was greater than 20 mm, and the number of malignant negative margins was 21 of 21 (100%) when the resected tumors had a margin distance greater than the maximum tumor diameter. Conclusions Malignant positive margins were not found when the margin distance was greater than the maximum tumor diameter, which was considered to be the optimal margin distance for prevention against margin relapse.