Regional patterns of early-onset colorectal cancer from the GEOCODE (Global Early-Onset COlorectal Cancer DatabasE)-European consortium: retrospective cohort study.

Background: The incidence of early-onset colorectal cancer is increasing, but in Europe this growth shows a heterogeneous pattern in different countries and regions.

Methods: Patients from six countries who participated in the Global Early-Onset COlorectal Cancer DatabasE (GEOCODE)-Europe group were included. The inclusion criteria were patients with colorectal adenocarcinoma diagnosed between 18 and 49 years of age, between January 2010 and December 2017, with at least 3 years of follow-up. Patients with inherited colorectal cancer syndromes were excluded.

Results: A total of 851 patients were included with almost equal sex distribution, most were diagnosed at age 39 years or older and 42% of patients were overweight or obese. Diagnoses were predominantly at later stages (62.5% stage III-IV) and tumours were predominantly located in the distal colon (76.9% left colon and rectum). Comparative analysis between countries demonstrated that the UK had a younger age at diagnosis and the Italian cohort had a higher prevalence of being overweight or obese. Patients from Luxembourg had more advanced stage diagnoses and those from The Netherlands had more polyps. Patients from the UK had a greater family history of colorectal cancer. Comparison of Mediterranean versus non-Mediterranean countries showed significant differences in the age at diagnosis and body mass index. The prevalence of early-onset colorectal cancer over the age of 40 years in Mediterranean versus non-Mediterranean countries was 71.4% versus 62.1% (P = 0.002), and early-onset colorectal cancer was diagnosed at a more advanced stage in Mediterranean countries versus non-Mediterranean countries (65.3% versus 54.7%; P = 0.033). Family history of colorectal cancer in a first-degree relative was more common in non-Mediterranean versus Mediterranean countries (19.1% versus 11.4%; P < 0.001).

Conclusion: This study highlights significant geographical disparities in the clinical, pathological and familial features of early-onset colorectal cancer across European countries.