Local Therapy of Metastases in Colorectal Cancer: Utilization and Survival in a Nationwide Population

PURPOSE: Local therapy (LT) for metastatic colorectal cancer (mCRC) is recommended when eradicating all metastases is feasible. Although LT is widely used, its population-level impact remains unclear. This study aims to use real-world population-based data to assess LT utilization and survival trends in mCRC. METHODS: Patients diagnosed with mCRC from 2010 to 2023 were included, using data from the Cancer Registry of Norway and the Norwegian Patient Registry. LT was defined as surgery, stereotactic radiotherapy (SRT), or ablation targeting liver, lung, or brain metastases. Outcomes were reported as median overall survival (OS) and 2-, 5-, and 10-year OS. The effect of the first versus last time period on survival was assessed using univariable and multivariable Cox regression. RESULTS: Among 64,112 CRC cases, 20,210 had mCRC. Of these, 21% received LT, 39% systemic therapy only, 12% other therapies, and 29% no therapy. Metastasectomy was the primary LT (87%), whereas SRT use was limited. LT use increased by 12% annually from 2010 to 2015 and then stabilized. The overall mCRC survival improved, with the 5-year OS increasing from 16% to 23% and the median OS from 15 to 18 months (adjusted hazard ratio, 0.92; 95% CI, 0.89 to 0.95). No significant survival improvement was observed between time periods in the LT or systemic therapy only subgroups. The 5-year OS for patients receiving LT for liver, lung, and brain metastases was 50%, 62%, and 5%, respectively. CONCLUSION: LT utilization increased, with outcomes comparable with more selected populations. Survival in treatment subgroups remained stable over time, but improved in the overall mCRC population, suggesting that the population-level gains may reflect changes in treatment allocation rather than improvements within modalities.