Introduction: The incidence of colorectal cancer in adults younger than 50 years has increased, but the trends of incidence in Switzerland has not been yet described. We assessed long-term incidence, stage distribution, and survival of early-onset colorectal cancer (EOCRC) in Switzerland.

Materials and methods: We conducted a nationwide, population-based study including all patients aged 20 years or older who were diagnosed with a first colorectal adenocarcinoma between 1980 and 2021, based on data from the National Cancer Dataset provided from the National Agency for Cancer Registration (NACR). Age-standardized incidence rates per 100'000 person-years were calculated using the 1976 European Standard Population. Temporal trends were assessed using joinpoint regression, expressed as annual percent change (APC). Stage distribution was analysed for 2010-21, when harmonized TNM data were available. Five-year net survival was estimated using the Pohar-Perme estimator.

Results: Among 96'410 patients, 5'928 (6.1%) were below 50 years old. Rectal cancers comprised 31.8% of EOCRC, versus 22.9% in those aged ≥ 75 years, whereas proximal colon cancers were less common (30.5% vs 42.7%, respectively). From 2010 to 2021, 27.7% of EOCRC were UICC stage IV, compared with 22.1% at ages 50-74 and 19.4% at ≥ 75. EOCRC incidence rose steadily (men: APC +0.46% [95% CI 0.17-0.76]; women: +0.49% [0.17-0.81]), driven by rectal cancers in both sexes and proximal colon cancers in young women. In contrast, incidence declined in older adults after the mid-2000s. Five-year net survival improved and reached a peak of 76.9% in 2010 for young men and 78.2% in 2007 for young women.

Discussion: EOCRC incidence in Switzerland has risen continuously, with advanced stage at diagnosis and heterogeneous survival gains, underscoring the need for adapted prevention, awareness, and screening strategies.

Title	Published in	Access level	OA Policy	Year	Views	Downloads

Rising early-onset colorectal cancer in Switzerland despite declining incidence in older adults : A nationwide population-based study, 1980–2021	European journal of cancer			2026	10	83

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