Predictive factors of pathologically proven noninvasive tumor characteristics in T1aN0M0 peripheral non-small cell lung cancer

Background: We 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. Methods: We 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. Results: Multivariate 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. Conclusion: The 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.