Risk factors and immune landscape of early local tumor progression after microwave ablation for lung cancer: a retrospective nested case-control study

Background and objectives Microwave ablation (MWA) is an effective therapy for early-stage inoperable non-small cell lung cancer (NSCLC), yet its efficacy is limited by early local tumor progression (LTP). As early LTP is often suggestive of incomplete ablation, this study aimed to identify its risk factors and to characterize the associated changes in systemic immune parameters. Methods This single-center retrospective nested case-control study enrolled patients with NSCLC who underwent MWA between January 1, 2021, and December 31, 2023. Patients were divided into an early LTP group (LTP ≤6 months post-MWA) and a control group. Clinical data and peripheral blood immune parameters at pre-MWA, one-week post-MWA, and one-month post-MWA were collected. Univariate and multivariate logistic regression analyses were used to identify independent risk factors and dynamic changes in immune indicators compared between groups. Results A total of 76 patients were included (19, early LTP group; 57, control group). Multivariate analysis identified three independent risk factors for early LTP: maximum tumor diameter >30 mm (OR = 2.681, 95%CI: 1.218–5.901, P = 0.014), distance to hilum ≤10 mm (OR = 3.280, 95%CI: 1.678–6.411, P = 0.001), and ablative safety margin (≤5.0 mm) (OR = 4.152, 95%CI: 1.922–8.968, P < 0.001). Comparative analysis of peripheral blood immune parameters revealed distinct patterns between groups at one-month post-MWA. Compared to the control group, the early LTP group exhibited a significant reduction in CD4 + T cells (P = 0.040) and IL-2 levels (P = 0.020), whereas IL-10 (P < 0.001) and IL-6 (P = 0.004) levels were significantly elevated. Conclusion Large tumor size, proximity to the pulmonary hilum, and an insufficient ablative safety margin are key risk factors for early LTP post-MWA. The development of early LTP is associated with significant alterations in specific peripheral blood immune cell subsets and cytokine levels at one-month post-MWA.