Comorbidities among American Indian and Alaska Native People with Cancer: A Surveillance, Epidemiology, and End Results-Medicare Study

BACKGROUND: Comorbidities may affect the incidence and management of cancers. The burden of comorbidities among American Indian and Alaska Native (AIAN) patients with cancer and survivors is unknown. METHODS: Using Surveillance, Epidemiology, and End Results-Medicare, we identified AIAN people aged ≥66 years diagnosed with female breast, lung, and colorectal cancers (2000-2019), with at least 1 year of Medicare coverage prior to diagnosis. We used latent class analysis (LCA) to identify comorbidity profiles and multinomial logistic regression to examine associations of class membership with sociodemographic characteristics. RESULTS: The mean NCI weighted comorbidity index was 0.53 (±0.59) for those with breast cancer, 0.59 (±0.65) for those with colorectal cancer, and 0.76 (±0.68) for those with lung cancer. For breast and colorectal cancers, LCA identified three classes (low, medium, and high comorbidities). For lung cancer, LCA identified four classes (two "medium" comorbidity classes differed in the proportion of chronic obstructive pulmonary disease and cardiovascular-related diseases). Sex, age, residence in a purchased/referred care delivery area, and year of diagnosis were associated with class membership for each cancer. Colorectal cancer class membership was associated with the proportion of the population with limited access to a grocery store; lung cancer class membership was associated with the proportion of the AIAN population with limited fluency in the English language. CONCLUSIONS: The NCI comorbidity score among AIAN people with cancer was slightly higher than published reports for those of non-Hispanic Whites. IMPACT: Managing comorbidities and cancer treatment may be complicated for AIAN people due to the provision of noncancer care within the Indian Health Service and the need to coordinate across multiple care systems.