Real-world comparative outcomes of chemo-immunotherapy versus chemotherapy in colon cancer: A multi-center retrospective cohort study.

e15579 Background: Immunotherapy and chemotherapy are key treatments for metastatic colon cancer, but their comparative effects on survival and adverse events remain unclear, warranting further investigation. Methods: This retrospective study used the TriNetX database (January 2017–December 2022) to evaluate patients with stage II-IV colon cancer. Outcomes were compared between patients receiving a combination of chemotherapy and immune checkpoint inhibitors with Ipilimumab, Pembrolizumab, Nivolumab, and Atezolizumab (chemo-immunotherapy), and those treated with chemotherapy alone (5-FU or capecitabine). Propensity score matching ensured balanced cohorts. Results: After matching, each cohort was reduced to 171 patients, achieving balance in demographics such as age (mean 64.9 ± 14.1 vs. 66 ± 13.5 years), sex (51.46% male vs. 49.70% male), ethnicity (59.06% vs. 55.56% non-Hispanic), and White race (63.74% vs. 67.25%). The median follow-up was shorter in the chemo-immunotherapy group (498 days; IQR: 944 days) compared to the chemotherapy group (772 days; IQR: 734 days). Median overall survival (OS) was significantly shorter in the chemo-immunotherapy group (648 days) compared to the chemotherapy group, with survival probabilities at the end of the time window of 40.75% and 58.94%, respectively. The hazard ratio (HR) for survival was 1.883 (95% CI: 1.356–2.616, p = 0.0001), indicating a significantly higher risk of mortality in the chemo-immunotherapy group compared to the chemotherapy group. The risk of Major Adverse Cardiovascular Events (MACE) was similar between the chemo-immunotherapy and chemotherapy groups (HR: 0.889, 95% CI: 0.608–1.299, p = 0.9209). The risk of Major Adverse Kidney Events (MAKE) was comparable between the groups (HR: 1.298, 95% CI: 0.843–1.998, p = 0.8126). The risk of liver metastases was higher in the chemo-immunotherapy group compared to the chemotherapy group (HR: 1.548, 95% CI: 1.127–2.126, p = 0.2519). The risk of gastrointestinal (GI) bleeding was similar between the two groups (HR: 1.537, 95% CI: 0.727–3.253, p = 0.7349). Conclusions: Chemo-immunotherapy in metastatic colon cancer showed a shorter overall survival compared to chemotherapy alone, with no significant differences in MACE, MAKE, liver metastases, or GI bleeding risks.