In a study to be presented by Unger et al at the 2019 ASCO Quality Care Symposium, researchers found patients living in socioeconomically deprived areas were more likely to experience worse survival in cancer clinical trials, even after adjustments for race and insurance (Abstract 162).
Methods
Researchers examined survival for patients enrolled in phase III clinical trials for all major cancers conducted by SWOG from 1985 to 2012. Socioeconomic deprivation was measured using residence zip codes linked to the Area Deprivation Index (ADI), a comprehensive index composed of 17 indicators reflecting socioeconomic variables which is scored from 0% to 100% and split into quintiles.
Five-year overall survival, progression-free survival, and cancer-specific survival were examined, adjusting for age (in 5-year intervals), sex, race, and, for a subset of patients, insurance status. Analyses were also stratified by cancer histology and stage. In total, 41,182 patients from 55 trials comprising 24 cancer histology and stage-specific strata were included in the analysis.
"In patients with cancer with access to protocol-directed care in clinical trials, area-level socioeconomic deprivation was associated with worse survival even after adjusting for patient-level race and insurance."— Unger et al
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Results
Compared to trial participants in areas with an ADI score of 0% to 20%, trial participants from areas with the highest socioeconomic deprivation (classified as ADI = 80%–100%) had worse overall survival (hazard ratio [HR] = 1.26, 95% confidence interval [CI] = 1.18–1.35; P < .001), progression-free survival (HR = 1.19, 95% CI = 1.12–1.27; P < .001) and cancer-specific survival (HR = 1.25, 95% CI = 1.17–1.35; P < .001). Results were similar after adjusting for insurance status (Medicaid/no insurance vs other). For each outcome, there was a continuous increase in risk of an event as the ADI quintile increased.
The authors concluded, “In patients with cancer with access to protocol-directed care in clinical trials, area-level socioeconomic deprivation was associated with worse survival even after adjusting for patient-level race and insurance. Future research should examine whether the etiology of this residual disparity is related to reduced access to supportive care or postprotocol therapy, and/or to differences in health status not reflected by protocol staging criteria. Policies to mitigate socioeconomic differences in cancer outcomes should emphasize access to cancer care services beyond initial therapy.”
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
