Owing to life expectancy improvements for people with intellectual disabilities, their risk of developing cancer is increasing. Pain is an inevitable aspect of cancerous diseases. However, as pain experience and expression can be atypical in people with intellectual disabilities, this population is vulnerable to late diagnosis of cancer and undertreatment of cancer pain.The objective of this study was to investigate what is currently known about cancer pain in people with intellectual disabilities and provide specific recommendations to improve this knowledge.A systematic review using PubMed, PsycINFO, and CINAHL and an anonymous online survey of Dutch health care professionals were conducted.From 10,146 publications, with intellectual disabilities in the title, and pain or cancer in the title or abstract, 11 articles underwent qualitative synthesis. Discussions within these articles were predominantly unspecific and brief, frequently indicating challenges in symptom presentation, communication, as well as assessment and treatment of cancer pain. The survey received 102 responses. The 63 health care professionals experienced with cancer in people with intellectual disabilities indicated challenges recognizing, assessing, and treating their cancer pain.Cancer pain in people with intellectual disabilities is a topic lacking specific and comprehensive research within scientific literature. We suggest this is due to inherent difficulties regarding the complex interplay of comorbidities and communication issues in people with intellectual disabilities.