Patients with cancer living in poorer areas have worse survival outcomes
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Cancer clinical trial participants living in poorer neighborhoods had worse OS, PFS and cancer-specific survival than those from affluent areas, according to results of a retrospective study published in Journal of Clinical Oncology.
Despite having the same access to protocol-directed care in clinical trials, patients living in areas with the highest levels of socioeconomic deprivation had a 28% increased risk for death compared with the wealthiest patients, results showed.
“Although it is known that socioeconomic deprivation is associated with poor outcomes in [patients with cancer], an unresolved question is whether these disparate outcomes remain after accounting for access to quality cancer care. But patients enrolled in clinical trials have access to guideline-based care by their participation in a trial,” Joseph M. Unger, PhD, SWOG Cancer Research Network health services researcher and biostatistician at Fred Hutchinson Cancer Research Center, told Healio. “This data source allowed us to rule out initial access to quality care as a principal confounding factor and answer the question of whether socioeconomic deprivation is still influential even among patients receiving state-of-the-art treatment.”
Unger and colleagues collected data of 41,109 patients with cancer (29% aged 65 years or older; 61.5% female; 10.3% Black; 10.4% with Medicaid or no insurance) enrolled in 55 phase 3 and large phase 2 clinical trials that SWOG conducted from 1982 to 2012. Most patients (71.8%) had either breast, colorectal, lung or prostate cancer, and 36.8% had advanced-stage disease.
They measured socioeconomic deprivation by using trial participants’ residential ZIP codes linked to the Area Deprivation Index (ADI) — for which researchers scored patients by quintile, from highest (most deprived, 81%-100%) to lowest (most affluent, 0%-20%) — which they then correlated with survival outcomes.
OS served as the study’s primary endpoint. Researchers examined 5-year OS, PFS and cancer-specific survival using Cox regression frailty models adjusted for age, sex, race and, separately, for insurance status, prognostic risk, and rural or urban residency.
Results showed, compared with trial participants in the most affluent areas, those from the areas with the highest socioeconomic deprivation had worse OS (HR = 1.28, 95% CI, 1.2-1.37), PFS (HR = 1.2, 95% CI, 1.13-1.28) and cancer-specific survival (HR = 1.27, 95% CI, 1.18-1.37).
“Although access to guideline-based care is obviously key to improving outcomes for [patients with cancer], it alone is not sufficient to eliminate disparate outcomes related to socioeconomic deprivation,” Unger said.
Moreover, the results were similar after adjusting for insurance status, prognostic risk, and rural or urban residency. Researchers also noted a continuous increase in risk as ADI quintile increased.
“I was surprised to see the very clear trend of a consistently increasing risk for death as the level of deprivation increased,” Unger said. “This suggests a kind of ‘dose response’ to the increasing burden of deprivation.”
Researchers noted that the study may be limited by a lack of patient-level socioeconomic information, but that ADI “likely correlates with individual-level measures” and “is useful in discriminating outcomes between different individuals in numerous settings.”
Socioeconomic disparities could be mitigated in the future with policies emphasizing access to care beyond initial treatment, including supportive care and reliable access to treatment if the patient’s cancer progresses, Unger said.
The next step of the research is underway, Unger added, as investigators examine clinical trial data on whether patients with limited to no insurance have different outcomes than patients with private insurance.
“This is a key extension of our work as it will help illuminate whether similar patterns are apparent when using an individual-level measure of socioeconomic status,” he said.
For more information:
Joseph M. Unger, PhD, can be reached at Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N, M3-C102, Seattle, WA 98109; email: junger@fredhutch.org.
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