Predictive Factors of Pathologically Proven Noninvasive Tumor Characteristics in T1aN0M0 Peripheral Non-small Cell Lung Cancer

BackgroundWe retrospectively analyzed preoperative factors that may predict pathologically invasive tumor characteristics, including lymph node involvement, and pleural and vessel invasion in patients with cT1aN0M0 peripheral non-small cell lung cancer (NSCLC), in an attempt to identify candidates for pulmonary resection less than lobectomy.MethodsWe reviewed the charts of 363 patients in whom cT1aN0M0 lung cancer in the lung periphery had been diagnosed or was suspected, based on high-resolution CT scan of 1- or 2-mm-slice intervals, within 1 month of surgical resection, and examined the relationships between preoperative clinical information and pathologic invasive tumor characteristics, corresponding to lymph node involvement and pleural and vessel invasion.ResultsMultivariate analysis showed that a tumor disappearance ratio (TDR) < 0.5, the presence of spiculation, and an absence of air bronchograms were statistically significant independent predictors of pathologic invasiveness. Most TDR ≥ 0.5 tumors were noninvasive (98.7%), and only one patient had a recurrence within 5 years after surgical resection. Of the tumors with a TDR ≥ 0.5 without spiculation, 98.3% were noninvasive, and all those patients remained recurrence-free for 5 years after surgery.ConclusionThe combination of a TDR ≥ 0.5 and the absence of spiculation was highly predictive of noninvasive or minimally invasive NSCLC. Future studies should evaluate whether limited resection of these tumors provides acceptable outcomes.