Prevalence and outcomes of cancer and treatment-associated toxicities for patients with ataxia telangiectasia

Background: Ataxia telangiectasia (A-T) is a DNA repair disorder with cancer predisposition. Objective: We sought to characterize the prevalence and outcomes of hematologic and solid cancers and treatment-associated toxicities in individuals with A-T. Methods: Data were retrospectively analyzed from the Johns Hopkins Ataxia Telangiectasia Clinical Center cohort. Cumulative incidence and standardized incidence ratios of cancer, survival probability after cancer diagnosis, and standardized mortality ratios were calculated. Cox regression estimated risk of death on the basis of chemotherapy (standard vs reduced) dosing, and multivariable logistic regression evaluated cancer risk associations with ataxia telangiectasia mutated (ATM) exons and variants. Results: Eighty-four (16.5%) of 508 individuals were diagnosed with a primary cancer, of whom 62 (74%) were hematologic in origin and 22 (26%) were solid-organ cancers. The cumulative incidence of cancer was 29% by age 35 years. Non–Hodgkin lymphoma occurred most frequently (n = 39), whereas solid cancers disproportionately affected those 18 years and older (n = 22). The standardized mortality ratio was 24.6 (95% CI, 21.1-28.4) overall and 232.9 (95% CI,178.1-299.2) among individuals with cancer. Risk of death was higher when treated with standard/unknown versus modified chemotherapy (hazard ratio, 2.2; 95% CI, 1.1-4.4; P =.024). Chemotherapy-associated toxicities developed in 58% of individuals, predominantly neurologic (n = 14) and gastrointestinal (n = 10) systems. Three exons were enriched for cancer-associated variants. Conclusions: Individuals with A-T experience a wide array of blood and solid-organ malignancies, high mortality rates, and treatment-related toxicities, highlighting need for targeted therapies to mitigate toxicity and optimize survival.