As reported in the Journal of Clinical Oncology by Joseph A. Unger, PhD, and colleagues, a large retrospective observational study investigating the association between socioeconomic deprivation and outcomes among patients with cancer enrolled in clinical trials has found that compared to patients in the most affluent areas, those living in the poorest neighborhoods had a nearly 30% greater chance of dying from their cancer. These findings suggest that access to quality cancer care as represented by treatment in a clinical trial is not enough to eliminate the disparate outcomes related to socioeconomic deprivation.
Joseph A. Unger, PhD
The association between low socioeconomic status and poor health outcomes has been well-documented for many diseases, including cancer. Patients who lack access to cancer screening and treatment often have more advanced stage disease at diagnosis and worse cancer outcomes, despite insurance status.
Study Methodology
The researchers examined survival outcomes for 41,109 patients enrolled in 55 phase III and large phase II clinical trials for major cancer types conducted by the SWOG Cancer Research Network from 1985 to 2012. Socioeconomic deprivation was measured using trial participants’ residential zip codes linked to the Area Deprivation Index (ADI). Five-year overall survival, progression-free survival, and cancer-specific survival were examined using Cox regression frailty models, adjusting for age, sex, and race, and separately for insurance status, prognostic risk, and rural or urban residency.
Results
The researchers found that compared with trial participants in the most affluent areas (ADI = 0%–20%), trial participants from areas with the highest socioeconomic deprivation (ADI = 80%–100%) had worse overall (hazard ratio [HR] = 1.28, 95% confidence interval [CI] = 1.20–1.37, P < .001), progression-free (HR = 1.20, 95% CI = 1.13–1.28, P < .001), and cancer-specific survival (HR = 1.27, 95% CI = 1.18–1.37, P < .001).
Compared with trial patients in the most affluent areas, patients from the highest socioeconomically deprived areas had a 28% increased risk of death (P < .001).
The results were similar after adjusting for insurance status, prognostic risk, and rural or urban residency. There was a continuous increase in risk of all outcomes as the ADI quintile increased.
KEY POINTS
- Compared with those enrolled in clinical trials in the most affluent areas, patients from the highest socioeconomically deprived areas had a 28% increased risk of death. The same pattern was found for progression-free and cancer-specific survival.
- Policies to mitigate socioeconomic differences in cancer outcomes should emphasize access to cancer care services beyond initial therapy.
- Understanding whether there are differences in outcomes for patients from poor areas receiving clinical trial care is important for researchers designing and interpreting clinical trials.
Clinical Relevance
According to the study authors, “Initial access to quality cancer care as represented by treatment in a clinical trial is insufficient to eliminate the disparate outcomes related to socioeconomic deprivation. Policies to mitigate socioeconomic differences in cancer outcomes should emphasize access to cancer care services beyond initial therapy.”
“Joining a clinical trial guarantees uniform, high-quality care, which should help improve outcomes for people with cancer,” said Dr. Unger, Associate Professor, Cancer Prevention Program in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center. “What’s surprising, and dismaying, to learn is that even though all patients benefit from trials, the poorest patients are still much more likely to die of their cancer. The disparity persists.”
Disclosure: Funding for the study was provided by the National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.
