Incidence Trends of Early-Onset Colorectal Cancer in Germany: A Registry-Based Study From 2003 to 2023.

Motivated by studies on early-onset colorectal cancer (EO CRC, below 50 years) from the United States (US) and elsewhere, this study aimed to provide national incidence trends of EO CRC for Germany. We retrieved colorectal cancer cases (ICD-10 codes C18-C20) using pooled data from German cancer registries with high-quality data. Appendix (C18.1) was excluded from the main analyses and investigated separately. We calculated age-standardised incidence rates (ASR) by calendar year, age group, sex, tumour site, histological subtype, tumour size, grading and estimated corresponding average annual percent changes (AAPC). For comparison, US cancer registry data was drawn from the Surveillance, Epidemiology, and End Results programs 21 population-based registries (SEER 21). From 2003 to 2023, ASRs of EO CRC (C18-C20 excluding C18.1) increased for men (AAPC: 0.8%) and women (AAPC: 0.9%) in Germany. By 10-year age groups, the increase was limited to men and women aged 20-29 years (AAPC males: 3.3%; AAPC females: 3.9%) and 30-39 years (AAPC males: 2.2%; AAPC females: 2.0%). For appendix cancer (C18.1), ASRs were rising for all age groups below 50 years of age. Increases for both colorectal cancer (excluding the appendix) and appendix cancer tended to be higher for cancers with good prognosis (neuroendocrine neoplasms, small size, low grading). In contrast to the US, Germany had a substantially lower EO CRC incidence in 2003 that increased at a slower pace. It is important to monitor future EO CRC incidence trends. The causes of the observed trends remain unclear.