New treatment strategies have improved survival of metastatic colorectal cancer in trials. However, it is not clear whether older patients benefit from these novel therapies, as they are often not included in pivotal trials. Therefore, we investigated treatment patterns and overall survival over time in older patients with metastatic colorectal cancer in a population-based study. We identified 22.192 Dutch patients aged ≥70 years diagnosed with synchronous metastatic colorectal cancer between 2005 and 2020 from the Netherlands Cancer Registry. Changes in treatment over time were assessed with logistic regression models. Survival was assessed by Cox proportional hazard ratios (HR). Results showed that chemotherapy use increased between 2005 and 2015, but declined from 2015 onwards, while more patients received best supportive care. Over time, fewer patients underwent primary tumor resection alone. Although survival of both metastatic colon and rectal cancer improved until 2014, survival of colon cancer decreased from 2014 onwards (HR 1.04, 95% confidence interval [CI] 1.01-1.05), which was seen in all age groups. Survival of metastatic rectal cancer patients remained unchanged from 2014 onwards (HR 1.00, 95% CI 0.98-1.03) in all age groups. In conclusion, treatment patterns of Dutch older patients with synchronous metastatic colorectal cancer rapidly changed from 2005 to 2020, with increasing percentages of patients receiving best supportive care. Survival of metastatic colon cancer decreased from 2014 onwards. The implementation of a colorectal cancer screening program and patient selection might explain why only a subset of older patients seem to benefit from the availability of novel treatment options.

© 2023 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.