Pulmonary Subsolid Nodules: Upfront Surgery or Watchful Waiting?

Abstract

Background: Patients with pulmonary subsolid nodules (SSNs) of ≤ 2 cm in diameter and a consolidation to tumor ratio (CTR) of ≤ 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 with diameter of ≤ 2 cm and CTR of ≤ 0.25?

Study design and methods: Patients with SSNs who underwent thin-section CT scan examination between February 2005 and December 2018 were followed up retrospectively until December 2023 or until all-cause death or lung cancer recurrence or metastases. Patients were divided into observation and surgery groups and categorized further 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 a noninferiority trial.

Results: Data from 1,676 patients were included (surgery group, n = 1,122 [66.9%]; observation group, n = 554 [33.1%]), with a median EFS of 70.2 months (range, 0.3-213.6 months). Comparing the observation group with the surgery group, the 5-year EFS rates in category A (diameter ≤ 2 cm and CTR ≤ 0.25), category A1 (diameter ≤ 1 cm and CTR ≤ 0.25), category A2 (1 cm < diameter ≤ 2 cm and CTR ≤ 0.25), and the combined category (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 < .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: In patients with SSNs of ≤ 2 cm in diameter and CTR of ≤ 0.25, watchful waiting could be more appropriate than upfront surgical intervention.

Keywords: follow-up; lung cancer; prognosis; pulmonary subsolid nodules; surgery.