eP722 - The Optimal Management of Isolated Synchronous Lung Metastasis in Stage IV Colon Cancer

Purpose/Background: The optimal treatment of isolated synchronous lung metastasis in stage IV colon cancer is unknown. Current National Comprehensive Cancer Network (NCCN) and the American Society of Colon and Rectal Surgeons (ASCRS) guidelines indicate a preference for surgical resection of lung metastasis in highly select patients, due to suggestions of improved overall survival (OS) compared to non-intervention. Guidelines suggest consideration of non-operative alternatives such as radiotherapy (RT), but OS related to these treatments is unknown. The aims of this study were to compare OS between surgical resection, RT, and non-intervention management approaches for lung metastasis and to evaluate treatment trends using a large national database.Methods/Interventions: Adult stage IV adenocarcinoma colon cancer patients with isolated synchronous lung metastasis who underwent both radical resection of the primary tumor and systemic chemotherapy were identified from the National Cancer Database (NCDB) (2010-2020). The primary outcome was 5-year OS, compared between the three management approaches (surgical resection vs. RT vs. non-intervention), analyzed using Kaplan-Meier survival curves, log-rank test and Cox proportional hazards models.Results/Outcomes: Among 1,834 included patients, 303 (16.5%) underwent surgical resection of lung metastasis, 67 (3.7%) underwent RT, and 1,464 (79.8%) had non-intervention. The proportion of patients receiving non-intervention for lung metastasis remained constant over the study period (from 81.9% in 2010-2012 to 80.8% in 2019-2020). The use of surgical resection decreased from 16.9% to 14.0% and RT increased from 1.2% to 5.3%. Median survival times for the surgical resection, RT, and non-intervention groups were 49.8 months, 43.2 months, and 38.6 months, respectively. There was no significant difference in the 5-year OS rates between surgical resection and RT (43.5% vs. 36.1%, respectively; p=0.337). Surgical resection was associated with a better OS when compared to the non-intervention group (43.5% vs. 30.4%, p < 0.001), though OS following RT was not significantly different from non-intervention (36.1% vs. 30.4%, respectively; p=0.197) (Figure 1). On adjusted analysis, there was no difference in the risk of mortality between the surgical resection and RT management groups (RT Hazards Ratios [HR] 1.10, 95% CI 0.73, 1.66, p=0.643). The non-intervention group was associated with an increased risk of mortality (HR 1.39, 95% CI 1.15, 1.68, p=0.001).Conclusion/

Discussion: Surgical resection of lung metastasis offers better 5-year OS than non-intervention for colon cancer patients with isolated synchronous lung metastasis. There was no difference in OS between the surgical resection and RT management groups. These results support current NCCN and ASCRS guideline preferences for surgical resection and suggest that in highly select patients RT may be an effective alternative to surgical resection.Figure 1Kaplan Meier 5-year overall survival curves stratified by treatment type.