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<0.001), liver only (aHR 0.51, 95% CI 0.46–0.57, p<0.001), and lung + liver (aHR 0.75, 95% CI 0.67–0.83, p<0.001) showed lower hazards of mortality over one year, while brain + liver (aHR 1.34, 95% CI 1.13–1.59, p=0.001), brain + bone (aHR 1.64, 95% CI 1.20–2.23, p=0.002), brain + liver + bone (aHR 1.89, 95% CI 1.50–2.38, p<0.001), and all four sites (aHR 1.74, 95% CI 1.45–2.09, p<0.001) showed higher hazards of mortality. Chemotherapy use ranged from 39.9% (brain only) to 65.6% (liver only). Radiation was most common in brain-involved groups (e.g., 53.7% in brain only). Primary-site surgery was most common in liver only (52.0%). Conclusions: In stage IV colon cancer, metastatic site patterns showed important heterogeneity in survival and treatment. Lung only and liver only groups had the highest OS, while brain-involved groups and all four sites had the worst OS. This data can directly inform prognosis counseling for patients by oncologists. Overall survival and treatment patterns by metastatic group (top 8). Metastatic Site Group n Median OS (mo) 6-mo OS (%) 1-yr OS (%) % Chemo % Radiation % Primary-site Surgery Liver only 71,952 16.1 69.9 57.3 65.6 2.5 52.0 Lung + Liver 17,683 9.7 59.0 44.5 62.7 2.0 29.4 Lung only 6,396 19.0 72.8 60.4 59.3 4.8 45.8 Liver + Bone 2,478 5.6 48.3 32.6 59.2 20.2 24.3 Lung + Liver + Bone 2,169 5.3 47.6 31.5 59.8 21.3 18.1 Bone only 1,292 5.8 49.3 34.2 46.3 27.1 30.0 Lung + Bone 503 5.3 46.8 30.8 52.7 27.6 18.3 Brain only 484 5.2 44.3 31.1 39.9 53.7 42.6 </jats