Evolving patterns of metastatic spread, treatment, and outcome for patients with oligometastatic colorectal cancer

Introduction: The assessment and management of oligometastatic colorectal cancer has evolved over the last two decades. We aimed to examine trends in the presentation, management and outcomes of patients presenting with liver-only disease, given recent changed standards for baseline imaging, and evolving definitions of resectability. Patients with lung-only disease can provide a contemporaneous control group. Methods: Prospectively maintained data from the multi-site Treatment of Recurrent and Advanced Colorectal Cancer Registry were reviewed over three consecutive periods; 2009–2013, 2014–2018, and 2019–2023. Survival outcomes were determined by Kaplan-Meier method. Results: Of 4613 patients with metastatic colorectal cancer, median age was 66 years (interquartile range 56–76), and 2356 (51 %) patients had a single metastatic site. Compared to the earlier periods, patients diagnosed in 2019–2023, were younger, had better ECOG scores and were more likely to have three or more metastatic sites. The proportion of patients with liver-only metastases decreased over the three consecutive periods, from 32.0 % (n = 462), to 27.0 % (n = 498) to 25.9 % (n = 33), p < 0.001, however the proportion of liver-only metastases patients undergoing resection increased from 41.5 to 59.3 %, p < 0.001. The incidence and resection rate of lung-only metastases was unchanged over time. Conclusion: The increasing number of metastatic sites and reduced number of patients with liver-only metastases is potentially explained by the increased use of FDG-PET imaging at baseline. The increased proportion of patients with liver-only disease undergoing resection may be explained by advancement in surgical techniques, improvements in systemic therapies and the evolving definition of resectable disease. Synopsis: The pattern and treatment of metastatic colorectal cancer has evolved over the last two decades. This study examines the trends in presentation management and outcomes of patients with metastatic colorectal cancer using a multi-site database.