Which T descriptor is more predictive of recurrence after sublobar resection: whole tumour size versus solid component size?

Abstract

We aimed to assess the predictive value of different T descriptors, including the whole tumour size (Dwhole) and solid component size (Dsolid), in patients with clinical Stage IA adenocarcinoma who underwent sublobar resection. According to computed tomography images in the lung window, T descriptors, Dwhole and Dsolid, were applied. To evaluate the predictive value of these 2 different descriptors in predicting tumour recurrence and pathological malignant behaviours, Cox hazard regression and a receiver-operating characteristic curve analysis, respectively, were used. In total, 247 patients were included. Of these patients, 109 and 138 had ground glass and solid nodules, respectively. When the T descriptor was changed from Dwhole to Dsolid, 37 tumours (15%) were downgraded to T1a status from T1b/T1c status. Multivariable Cox analysis showed that Dsolid was an independent risk factor of worse recurrence-free survival [hazard ratio (HR) 2.36, 95% confidence interval (CI) 1.24-4.47; P = 0.009], while Dwhole was not (HR 1.51, 95% CI 0.79-2.89; P = 0.215). In the receiver-operating characteristic analysis, the areas under the curves for Dwhole and Dsolid used to identify pathological malignant behaviours were 0.598 and 0.739, respectively. The T descriptor, which is represented by Dsolid, rather than Dwhole, is a better predictor of tumour recurrence after sublobar resection in clinical Stage IA lung adenocarcinoma. Furthermore, our results provide some clues indicating that sublobar resection should be performed cautiously in patients with lung adenocarcinoma manifesting as ground glass nodule with Dsolid >2 cm.