Early-onset gastrointestinal cancer patterns in Navarre: incidence, tumour features and patient survival outcomes.

BACKGROUND: Despite growing awareness of the rising incidence and particular features of early-onset gastrointestinal cancer (EOGIC), evidence from Spain remains limited. The purpose of this study was to compare EOGIC with average-onset gastrointestinal cancer (AOGIC) in Navarre, by analysing incidence trends, clinicopathological features and patients' relative survival (RS). MATERIALS AND METHODS: Patients with EOGIC (18-49 years) and AOGIC (≥50 years) diagnosed with colorectal, gastroesophageal, pancreatic and hepatobiliary cancer between 2015 and 2025 were considered. Incidence trends were evaluated using age-standardised incidence rates and annual percentage changes (APCs); survival outcomes were estimated through RS and relative excess risk (RER). RESULTS: A total of 5053 patients were included, of whom 5.38% were EOGIC. Although the incidence of AOGIC declined (APC = -2.80, P < 0.05), the incidence of EOGIC remained stable (APC = 1.77, P = 0.547). Patients with EOGIC presented with more advanced tumour stages (P < 0.05), and those with early-onset gastroesophageal and pancreatic ductal adenocarcinoma (EOGEA and EOPDAC) were enriched with poorly differentiated tumours (P < 0.05). Diffuse histology was more represented in EOGEA (P < 0.05). Patients with EOGIC presented similar 3-year RS (P = 0.911) and a comparable RER to patients with AOGIC. In contrast, by tumour stage, patients with EOGIC with locally advanced or metastatic tumours exhibited better 3-year RS (P < 0.05) and lower stage-adjusted RER (RER 0.738, P < 0.05). CONCLUSIONS: The incidence of EOGIC in Navarre remained stable, whereas AOGIC declined. Patients with EOGIC were mostly females, presented with more aggressive tumours and had lower stage-adjusted mortality risk.