Cancer Risk in Patients with Down Syndrome—A Retrospective Cohort Study from Germany

Background: Individuals with Down syndrome are thought to have a unique tumor profile. Methods: Using the IQVIA Disease Analyzer database, patients aged ≥18 years diagnosed with Down syndrome in German general practices between 2005 and 2021 were compared with patients without Down syndrome for cancer incidence, adjusting for age, sex, average annual visit frequency, and comorbidity. The 5-year cumulative incidence of cancer overall and specific cancers was analyzed using Kaplan–Meier curves and compared using the log-rank test. In addition, univariable Cox regression analysis was performed. Results: A total of 2438 patients with Down syndrome and 12,190 patients without Down syndrome were included; 3.9% of patients with Down syndrome and 3.1% of patients without Down syndrome were diagnosed with cancer (p = 0.143). Regression analysis showed no significant association between Down syndrome and subsequent cancer in the total population (HR: 0.79; 95% CI: 0.57–1.09), in women (HR: 0.89; 95% CI: 0.56–1.37), or in men (HR: 0.69; 95% CI: 0.43–1.11). Analyses by cancer type and sex showed a strong but not significant negative association between Down syndrome and breast cancer in women (HR: 0.33; 95% CI: 0.12–0.93). Conclusions: Our results could form the basis for future studies to clarify whether and to what extent an adapted screening program needs to be modified for individuals with Down syndrome due to the particular cancer distribution pattern.