Objectives: Phase III trials regarding the feasibility of segmentectomy for lung cancer ≤ 2 cm in size are now underway in Japan and the USA. However, despite their small size, lung cancers that show a pure-solid appearance on thin-section computed tomography (CT) are considered to be invasive with a high frequency of nodal involvement.
Methods: Between 2008 and 2011, 556 clinical Stage IA lung cancer patients underwent pulmonary resection. For all patients, the findings obtained by preoperative thin-section CT were reviewed and the maximum standardized uptake value (SUVmax) on positron emission tomography was recorded. Several clinicopathological features were investigated to identify predictors of nodal metastasis using multivariate analyses.
Results: One hundred and eighty-four clinical Stage IA lung cancer patients showed a pure-solid appearance on thin-section CT. Among them, air bronchogram was found radiologically in 58 (32%) patients. Nodal involvement was observed in 10 (17%) patients with air bronchogram, compared with 43 (34%) without air bronchogram, in clinical Stage IA pure-solid lung cancer. A multivariate analysis revealed that air bronchogram, clinical T1a and SUVmax were significant predictors of postoperative nodal involvement (P < 0.01, <0.01, and 0.03, respectively). Furthermore, nodal metastasis was never seen in patients with clinical T1a pure-solid lung cancers who had both air bronchogram and low SUVmax.
Conclusions: The presence of air bronchogram was a novel predictor of negative nodal involvement in clinical Stage IA pure-solid lung cancer. Segmentectomy with thorough lymph node dissection is a feasible option for these patients despite a pure-solid appearance.
Keywords: Air bronchogram; Lymph node metastasis; Prognosis; Pure-solid nodule.