Disparities in the Occurrence of Long-Term Effects of Bone Marrow Suppression after Treatment in Adolescent Young Adult Breast Cancer Survivors.

Background: Many adolescent and young adult (AYA) patients with breast cancer (BC) receive adjuvant therapy as initial treatment, with long-term bone marrow suppression as a potential complication, but no studies have evaluated the impact of race/ethnicity on the development of bone marrow suppression in AYA BC survivors.

Patients And Methods: Female patients ages 15-39 years diagnosed with BC (2006-2018) and surviving ≥ 2 years were identified from the California Cancer Registry and linked to statewide hospitalization data. We estimated the cumulative incidence of developing late effects of bone marrow suppression, such as leukopenia, anemia, thrombocytopenia, bleeding, and infection/sepsis, during hospital discharge diagnoses present ≥ 2 years after diagnosis. We examined the impact of sociodemographic and clinical factors on late effects using multivariate Cox proportional hazards regression.

Results: Of 11,293 patients, 42.8% were non-Hispanic (nH) White, 28.8% Hispanic, 19.5% nH Asian/Pacific Islander, and 7.5% nH Black. In multivariable analyses, nH Blacks had the highest risk (versus nH Whites) of anemia [hazard ratio (HR) 1.72, 95% confidence interval (CI) 1.47-2.02], leukopenia (HR 1.56, CI 1.14-2.13), thrombocytopenia (HR 1.46, CI 1.08-1.99), major infection/sepsis (HR 1.64, CI 1.4-1.92), and bleeding (HR 1.89, CI 1.39-2.58). Hispanics had a higher risk of developing anemia (HR 1.17, CI 1.04-1.32), bleeding (HR 1.4, CI 1.12-1.76), and major infections/sepsis (HR 1.36, CI 1.21-1.52). Asian/Pacific Islanders had only a higher risk of developing bleeding (HR 1.33, CI 1.03-1.72). Patients from a low neighborhood socioeconomic status had a 20% higher risk of infection/sepsis (HR 1.21, CI 1.1-1.34), but there were no associations for the other late effects.

Conclusions: We identified that AYAs of nH Black, Hispanic, and Asian/Pacific Islander race/ethnicity are at an increased risk of several late effects after adjuvant therapy compared with nH White patients. From these data, providers can implement early/frequent screening of hematologic late effects in these high-risk survivors.