Association of advanced age and cancer history with autoimmune disease in melanoma patients: a cross-sectional study

Immune-related adverse events (irAEs) are a major toxicity of immune checkpoint inhibitors. Studies have reported that pre-existing autoimmunity increases the risk of irAEs, but it remains unknown which clinical factors are linked to auto-immune disorders in cancer patients. This study aimed to evaluate if the prevalence of autoimmune diseases varied by specific cancer history and advanced age. Our cross-sectional medical record review consisted of 291,333 patients (age, ≥18 years) treated between 2000 and 2018. Patients were classified into four study groups (melanoma only, non-cutaneous solid cancer only, melanoma and non-cutaneous cancer, and no cancer history). Dependent variable was the presence of ≥1 autoimmune disorders based on 98 conditions using 317 ICD codes. Non-cutaneous cancer, in the absence or presence of melanoma, was associated with a higher prevalence of autoimmunity (16.5, 95% CI 16.1-16.9; 20.0, 95% CI 18.3-21.7, respectively) compared to the rates in patients with melanoma only and those without cancer history (9.3, 95% CI 8.6-10.0; 6.2, 95% CI 6.1-6.3, respectively). Among patients with metastases at initial presentation, those in the melanoma and non-cutaneous cancer group had a prevalence of 24.0% (95% CI 20.1-27.9) compared to 19.1% (95% CI 17.2-21.0) in those without metastases. Multiple logistic regression demonstrated that patients > 75 years exhibited the highest odds of autoimmunity relative to other age groups, with age 18-34 as the referent (OR, 1.78, 95% CI 1.67-1.89). Among patients with melanoma, the greatest prevalence of autoimmunity occurred with advanced age and a history of non-cutaneous cancer.