Individuals with intellectual or developmental disabilities (IDD) experience lifelong limitations in both intellectual and adaptive functioning, which manifest during the developmental period and make up approximately 1–3 % of the population. [1]. Cancer is among the leading causes of death for adults with IDD [2]. However, data on cancer epidemiology for people with IDD are scarce. One hypothesis suggests that delayed diagnoses result in a greater risk of disseminated disease and worse cancer survival. Persons with IDD may experience diminished capacity in verbal communication or reasoning, perceiving, and processing new information, and problem solving, which may create difficulties in recognizing and communicating cancer-related signs and symptoms [3], [4]. A dependency on others can also create barriers to accessing healthcare, which may hinder a timely cancer diagnosis. Higher rates of cardiovascular disease, diabetes, respiratory diseases, and other illnesses and management of their multimorbidity may also interfere with a timely diagnosis [5]. Adults with IDD also disproportionately experience social risk factors, such as low income and low education [3], [4]. Finally, a lack of healthcare provider knowledge, gatekeeping from caregivers, and biases such as ableism may further influence worse cancer outcomes [3], [4]. In the cancer literature, many of these same risk factors have well-established relationships to delayed cancer diagnoses and advanced stage at diagnosis [6], [7]. While there is evidence suggesting adults with IDD have lower rates of cancer screening than the general population, [8], [9] the relationship between IDD and stage at diagnosis is unestablished [10].