Occurrence of cancer in people with intellectual disabilities in Germany.
Authors: Sappok Tanja , Rosenbusch Marie-Luise , Hering Ramona , Schulz Mandy , Kowalski Christoph , Sibert Nora Tabea , Seufferlein Thomas , Berger Andreas 
Published: May 2024

1595 Background: Intellectual disability (ID) affects about 1% of the general population, involving approximately 1 million people in Germany. People with ID experience shorter life expectancies and one of the most common causes of death include malignancies (20%). In addition to life-style factors, possibly genetic mutations causing ID may contribute to oncogenesis. Whether individuals with ID have a higher-than-expected risk of cancer in Germany remains unknown. Methods: A cross-sectional study was conducted using nationwide outpatient health insurance data in Germany from 2019. The data set included 438 028 people with ID and 65 762 146 people without ID (0-107 years, male/female). After matching for age, sex, and district code, data from 437 802 people with ID (4.23 % with cancer) and 4 378 020 without ID (5.06 % with cancer) aged 0-95 years were analyzed. Univariate odds ratios estimated the association between ID and cancer occurrence for various cancer diagnoses (ICD-10: C00-C97). The study was approved by the ethics committee of the Berlin Medical Association (Eth-11/23). Results: Across all cancer types, people with ID showed lower risks for a cancer diagnosis than those without ID (Odds Ratio [OR] 0.83; 95% Confidence Interval [95% CI] 0.82-0.84); p < .0001 for all data. Certain cancer types occurred more often, such as malignant neoplasms of the brain (C71; OR 2.80; 95% CI 2.58-3.03), other parts of the central nervous system (C72; OR 2.45; 95% CI 1.76-3.34), the testicles (C62; OR 1.80; 95% CI 1.68-1.93), the ovary (C56; OR 1.26; 95% CI 1.13-1.4), the corpus uteri (C54; OR 2.02; 95% CI 1.86-2.19), leukemia of unspecified cell type (C95; OR 1.86; 95% CI 1.67-2.06) and other leukemia of specified cell type (C94; OR 1.81; 95% CI 1.43-2.25). However, other entities such as malignant melanomas (C43; OR 0.55; 95% CI 0.51-0.59), prostate cancer (C61; OR 0.59; 95% CI 0.56-0.62), tumors in the respiratory system (C30-39; OR 0.69; 95% CI 0.64-0.74) and the breast (C50; OR 0.82; 95% CI 0.79-0.85) occurred less often. Conclusions: People with ID showed a decreased risk for being diagnosed with cancer. This may be caused by lower exposition to certain risk factors in some cancer types such as skin or lung cancers. Difficulties in accessing the health care system and lower cancer screening rates leading to fewer diagnoses may partly explain the results. Later recognition of cancer in a more advanced stage of the disease may be associated with premature deaths and lead to lower prevalence rates. Certain oncological diseases such as malignant neoplasms of the central nervous system, urogenital tumors and hematological neoplasms require a special focus in prevention and therapy. Medical services, screening programs and patient education for people with ID need to be established, adapted and expanded to meet the needs of people with ID and to reach this highly vulnerable population group for guideline-based oncological screening and treatment.