The Clinical Relevance of Indeterminate Pulmonary Nodules in Patients Amenable to Local Treatment of Colorectal Liver Metastases

Objective: Indeterminate pulmonary nodules are common in patients with colorectal liver metastases (CRLM), and can lead to treatment dilemmas. This study evaluates the clinical relevance of indeterminate pulmonary nodules in patients amenable for local treatment of CRLM. Background: The incidence and prognosis of patients with CRLM and indeterminate pulmonary nodules is unknown. Only small retrospective studies have examined outcomes, and no consensus exists on the optimal management. It remains unknown if the presence of indeterminate pulmonary nodules impacts survival. Methods: All patients who underwent liver resection and/or thermal ablation for CRLM between 2000 and 2021 at a single tertiary centre, were included in the study. Patients with extra-hepatic disease were excluded. Patients were divided into 2 groups based on the absence or presence of indeterminate pulmonary nodules at the time of diagnosis of the CRLM. Indeterminate pulmonary nodules were defined as intrapulmonary nodules of which the nature could not be determined by the radiologist. The primary outcome measure was 5-year overall survival. The secondary outcome measures were disease-free survival and cumulative incidence of lung metastases. Results: A total of 1008 patients were included, of whom 277 (27.5%) presented with indeterminate pulmonary nodules at time of first local treatment of CRLM. The 5-year overall survival in patients with or without indeterminate pulmonary nodules was 40.1% and 44.4%, respectively ( P = 0.14). Corresponding 5-year disease-free survival was 19.0% and 20.4% and ( P = 0.1). The 5-year cumulative incidence of lung metastases was 45.8% for patients with indeterminate pulmonary nodules and 37.6% for patients without ( P = 0.001). Conclusions: More than a quarter of patients who were candidates for local treatment of CRLM presented with indeterminate pulmonary nodules. Although these patients were more likely to develop lung metastases, this did not significantly affect disease-free survival nor overall survival.