Optimising outcomes in young-onset metastatic colorectal cancer from a multidisciplinary model of care.

Abstract

56 Background: Australia has the highest incidence of young-onset colorectal cancer (yo-CRC) globally (1). Many young patients present with advanced-stage disease, contributing to poor survival outcomes. Contemporary survival data for young-onset metastatic colorectal cancer (yo-mCRC) is limited; the best estimates are based on a QLD study of patients treated between 2000–2020, reporting a 5-year survival of 19% in yo-CRC versus 10% in older adults (2). Methods: Building on our 2024 data demonstrating 5-year survival rate of 70% in selected yo-mCRC patients (3), we analysed a broader real-world cohort of mCRC patients (n=137) treated within out MDT model. All patients treated since 2016 with a minimum follow up of 3 years were included. The objective was to evaluate survival outcomes and the key enablers of success in radical-intent management. Results: Treatment intent emerged as the strongest predictor of long-term outcomes. Of the 137 patients, 6 were untreatable. Five year survival of all treatable patients was 43% (56/131). Among 131 treatable patients, radical intent - defined as a multimodality strategy aiming for substantial remission or cure - was feasible in 64% of patients aged <55 and 53% of those >55. In this group, 5-year survival was 71.6% for >55 and 86.9% (estimated) for <55, demonstrating that outcomes comparable to leading international benchmarks are achievable in Australia using currently available therapies (4,5). Radical intent was maintained even in patients with unresectable disease, challenging the conventional dichotomy of resectable vs. non-resectable mCRC. Enablers of radical treatment included good performance status, ability to tolerate doublet/triplet chemotherapy ± biologics and absence of M1c disease. Molecular profile of RAS/RAF wild-type emerged as an independent favourable factor. Conclusions: In a real world cohort, radical-intent treatment was feasible in the majority of assessable yo-mCRC patients and offers the potential for long-term survival and cure. Multimodality management with curative intent, even in technically unresectable cases, represents a critical strategy to improve outcomes. These findings highlight the urgent need for national visibility, early referral systems, and equitable access to curative-intent MDT pathways for young Australians living with metastatic colorectal cancer.