Pulmonary subsolid nodules: upfront surgery or watchful waiting?

Background: Patients with pulmonary subsolid nodules (SSNs) ≤ 2 cm in diameter and a consolidation-to-tumor ratio (CTR) ≤ 0.25 have good postoperative prognoses, but their management remains controversial.

Research Question: Does upfront surgical intervention lead to higher survival than watchful waiting in patients with SSNs diameter ≤ 2 cm and CTR ≤ 0.25?

Study Design And Methods: Patients with SSNs who underwent thin-section CT examination between February 2005 and December 2018 were retrospectively followed until December 2023 or until all-cause death or lung cancer recurrence/metastases. Patients were divided into observation and surgery groups and further categorized by the diameter and CTR of these SSNs. Event-free survival (EFS) was evaluated using Kaplan-Meier analysis, multivariable-adjusted Cox proportional hazards modeling, propensity score matching, and non-inferiority trial.

Results: Data from 1676 patients were enrolled (surgery group: 1122 [66.9%]; observation group: 554 [33.1%]), with a median EFS of 70.2 (range 0.3-213.6) months. Comparing the observation group to the surgery group, the 5-year EFS rates in categories A (diameter ≤ 2 cm and CTR ≤ 0.25), A1 (diameter ≤ 1 cm and CTR ≤ 0.25), A2 (1 cm < diameter ≤ 2 cm and CTR ≤ 0.25), and Combined (diameter ≤ 3 cm and CTR ≤ 0.5) were 100% vs. 99.0%, 100% vs. 99.6%, 100% vs. 98.6%, and 100% vs. 97.4%, respectively. In the above categories of SSNs, the EFS of the observation group was noninferior to that of the surgery group (P < 0.001 for noninferiority), and the results remained consistent after propensity score matching. Category A2 achieved the maximum hazard ratio of 0.0668, with corresponding 5-year EFS rates for the observation and surgery groups being 100% vs. 93.3%, respectively.

Interpretation: Patients with SSNs ≤ 2 cm in diameter and CTR ≤ 0.25, watchful waiting could be more appropriate than upfront surgical intervention.