What is the clinical evidence from this study?

Study design: Cohort. Population: Cancer (n=904995). Intervention: Black race vs. White race. Primary outcome: Cardiovascular disease mortality (HR 1.30-4.04).

July 20, 2023Open Access

Mediators of Black–White inequities in cardiovascular mortality among survivors of 18 cancers in the USA

Key Result

Black cancer survivors had a higher risk of cardiovascular mortality than White survivors across 18 cancer types (HR 1.30-4.04), largely mediated by neighborhood socioeconomic status and insurance.

Study Design

Type

Cohort (n=904,995)

Multicenter

Yes

Structured PICO

Does Black race increase cardiovascular disease mortality compared to White race among adult-onset cancer survivors?

Population

904,995 US survivors of 18 adult-onset cancers diagnosed at ages 20-64 years during 2007-16 from 17 Surveillance, Epidemiology and End Results registries

Intervention

Black race

Comparator

White race

Outcome

Cardiovascular disease (CVD) mortalityhard clinical

Socioeconomic factors, particularly neighborhood socioeconomic status and health insurance, are major mediators of the racial disparities in cardiovascular mortality among cancer survivors.

Main Result

Effect estimate: HR 1.30-4.04

Absolute Event Rate: 1.9% vs 1%

Limitations

Wide CIs for less common cancers due to limited statistical power
Causes of death based on death certificates are subject to misclassification
Missed mediations and residual confounding due to incompleteness of covariates
Lack of individual-level SES and cardiovascular risk factors in SEER
SEER registries cover only 28% of the US population

Abstract

BACKGROUND: This study aims to quantify Black-White inequities in cardiovascular disease (CVD) mortality among US survivors of 18 adult-onset cancers and the extent to which these inequities are explained by differences in socio-economic and clinical factors. METHODS: Survivors of cancers diagnosed at ages 20-64 years during 2007-16 were identified from 17 Surveillance, Epidemiology and End Results registries. Associations between race and CVD mortality were examined using proportional hazards models. Mediation analyses were performed to quantify the contributions of potential mediators, including socio-economic health insurance, neighbourhood socio-economic status (nSES), rurality and clinical (stage, surgery, chemotherapy, radiotherapy) factors. RESULTS: Among 904 995 survivors, 10 701 CVD deaths occurred (median follow-up, 43 months). Black survivors were more likely than White survivors to die from CVD for all 18 cancers with hazard ratios ranging from 1.30 (95% CI = 1.15-1.47) for lung cancer to 4.04 for brain cancer (95% CI = 2.79-5.83). The total percentage mediations (indirect effects) ranged from 24.8% for brain (95% CI=-5.2-59.6%) to 99.8% for lung (95% CI = 61.0-167%) cancers. Neighbourhood SES was identified as the strongest mediator for 14 cancers with percentage mediations varying from 25.0% for kidney cancer (95% CI = 14.1-36.3%) to 63.5% for lung cancer (95% CI = 36.5-108.7%). Insurance ranked second for 12 cancers with percentage mediations ranging from 12.3% for leukaemia (95% CI = 0.7-46.7%) to 31.3% for thyroid cancer (95% CI = 10.4-82.7%). CONCLUSIONS: Insurance and nSES explained substantial proportions of the excess CVD mortality among Black survivors. Mitigating the effects of unequal access to care and differing opportunities for healthy living among neighbourhoods could substantially reduce racial inequities in CVD mortality among cancer survivors.

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