What Is the Evidence Base Regarding Early Onset Colorectal Cancer in Australia and New Zealand? A Scoping Review

Early onset colorectal cancer (EoCRC), commonly defined as colorectal cancer diagnosed in people under 50 years of age, is increasing in incidence in Australia and New Zealand. The underlying cause of this remains unclear, despite its growing public health importance. The objective of this scoping review was to comprehensively map and synthesise the literature for EoCRC across Australia and New Zealand, focusing on themes and data sources.

A scoping review was performed according to the PRISMA guidance.

English language, humans, publications 01/01/2000-31/05/2025, Australian and/or New Zealand patients, studies addressing EoCRC (adenocarcinoma). A systematic literature review was performed: 698 titles and abstracts were screened, 72 full texts were reviewed, with 59 studies included for final analysis.

Studies were mostly derived from national and state-based cancer registries and thus presented results achievable by analysis of these databases: incidence, patient demographics, familial cancer syndromes and genetics, tumour characteristics, treatment, short term outcomes and survival. Direct comparison between studies was difficult due to the heterogeneity of patient groups and outcome measures. Gaps identified in the literature included lack of longitudinal risk factor analysis and detailed clinicopathological data.

Australia and New Zealand benefit from the mandatory reporting of colon cancer into central registries. To further progress our understanding of EoCRC, prospectively collected and detailed clinicopathological data are required. Despite relatively small populations, the incidence of colorectal cancer in Australia and New Zealand remains among the highest in the world; insights obtained locally have potential global impact.