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

OBJECTIVES: We aimed to assess the predictive value of different T descriptors, including the whole tumour size (D-whole) and solid component size (D-solid), in patients with clinical Stage IA adenocarcinoma who underwent sublobar resection. METHODS: According to computed tomography images in the lung window, T descriptors, D-whole and D-solid, 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. RESULTS: 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 D-whole to D-solid, 37 tumours (15%) were downgraded to T1a status from T1b/ T1c status. Multivariable Cox analysis showed that D-solid 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 D-whole 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 D-whole and D-solid used to identify pathological malignant behaviours were 0.598 and 0.739, respectively. CONCLUSIONS: The T descriptor, which is represented by D-solid, rather than D-whole, 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 D-solid >2 cm.