Tumor size-dependent outcomes of radiofrequency ablation for colorectal cancer pulmonary metastases: a single-center retrospective study

Abstract Radiofrequency ablation (RFA) is an established local therapy for inoperable colorectal cancer pulmonary metastases, with proven efficacy for lesions ≤ 3 cm. However, the optimal selection criteria, particularly for tumors sized 2–3 cm, remain unclear due to conflicting survival data. This single-center retrospective study (2016–2024) aimed to compare the long-term outcomes of RFA in 237 patients stratified by tumor diameter: Group 1 (≤ 2 cm, n = 126) and Group 2 (2–3 cm, n = 111). After a median follow-up of 40.6 months, Group 1 demonstrated a superior 5-year overall survival (OS) of 90.6% versus 69.4% in Group 2 ( P = 0.019). Yet, this association was not independent in multivariable analysis, where tumor size was confounded by factors including pleural distance and procedural complications. Notably, the 5-year local tumor progression (LTP) rate was significantly higher in Group 2 (26.4% vs. 12.2%, P = 0.00037). Multivariable analysis identified a lesion distance > 1 cm from the pleura as an independent favorable prognostic factor for OS (HR = 0.42, P = 0.042), while post-RFA alveolar hemorrhage was a strong predictor of mortality (HR = 7.22, P < 0.001). In conclusion, RFA provides excellent local control and survival for metastases ≤ 2 cm, especially when located > 1 cm from the pleura. For tumors sized 2–3 cm, the significantly higher LTP risk suggests that these patients may benefit from more aggressive strategies, such as combining RFA with adjuvant systemic therapy or considering alternative ablation modalities like microwave ablation. Graphical Abstract