Survival outcomes and treatment patterns by specific metastatic sites in stage IV colon cancer: A national registry analysis.

82 Background: Existing studies of metastatic colon cancer often group patients with more than one metastatic site into a “multiple” category or focus only on single-organ metastases. To address this gap, we used a large, real-world national registry to analyze survival outcomes and treatment patterns by specific combination of metastases in patients presenting with stage IV colon cancer. Methods: Adult patients with de-novo stage IV colon cancer diagnosed from 2010 to 2020 were identified from the National Cancer Database. Patients with brain, lung, liver, and/or bone metastases were classified into metastatic site groups. Median overall survival (OS) and 6- and 12-month OS were calculated. Multivariable Cox regression (censored at 12 months) adjusted for age, comorbidity score, race/ethnicity, facility type, and diagnosis year. Treatments analyzed included chemotherapy, radiation, and primary-site (colon) surgery. Results: Of 775,733 patients with colon cancer, 162,879 had stage IV disease at diagnosis, of whom 104,466 had complete data for analysis. The largest metastasis groups were liver only (n=71,952) and lung only (n=6,396). Median OS ranged from 2.7 months (all four sites) to 19.0 months (lung only). One-year OS ranged from 31.1% for brain only to 57.3% for liver only to 60.4% for lung only. In adjusted Cox models (compared to brain only as reference), lung only (aHR 0.40, 95% CI 0.36–0.45, p