Extrapulmonary metastases impact survival outcomes of thermal ablation for colorectal lung oligometastases: A multicenter study

BACKGROUND Colorectal cancer (CRC) frequently metastasizes to the lungs, and image-guided thermal ablation (IGTA) has emerged as a promising treatment for oligometastatic colorectal lung metastases (CRLM). However, high-quality multicenter data remain limited, and the prognostic impact of site-specific extrapulmonary metastases is not well defined. AIM To assess IGTA efficacy in potentially curable oligometastatic CRLM and determine prognostic impacts of extrapulmonary metastatic patterns. METHODS This multicenter real-world study analyzed 336 CRLM patients treated with IGTA from 2014 to 2022. Inclusion criteria included pathologically or clinically confirmed oligometastatic CRC, tumor diameter < 50 mm, fewer than 5 metastatic lesions, and ≤ 2 organs involved. Kaplan-Meier and Cox regression methods assessed survival outcomes, including local tumor progression-free survival, progression-free survival (PFS), and overall survival (OS). RESULTS The 3-year cumulative local tumor progression rate was 14.0%. Median PFS and OS were 15.6 and 51 months, respectively, with 3- and 5-year OS rates of 59.5% and 41.0%. Poor survival outcomes were associated with a higher tumor burden (larger size and greater number), carcinoembryonic antigen > 20 ng/mL, carbohydrate antigen 19-9 > 37 U/mL, and extrapulmonary metastases. Patients without extrapulmonary metastasis had 1-, 3-, and 5-year PFS rates of 65.4%, 31.0%, and 27.3%, respectively, which were longer than those of CRLM patients with liver metastasis [hazard ratio (HR) = 1.449, P = 0.019] and abdominal cavity metastasis (HR = 1.864, P = 0.010). The 1-, 3-, and 5-year OS rates for patients without extrapulmonary metastasis were 96.4%, 71.0%, and 53.0%, respectively, which were significantly longer than those for patients with bone metastasis (HR = 4.538, P < 0.001), abdominal cavity metastasis (HR = 4.813, P < 0.001), and pelvic cavity metastasis (HR = 3.105, P < 0.001). CONCLUSION Metastatic patterns significantly influence PFS and OS, emphasizing the need for careful patient selection. Notably, patients with liver-only extrapulmonary metastasis demonstrate comparatively favorable outcomes, suggesting a distinct biological behavior and better prognosis within this subgroup.