medwireNews: Researchers have identified an association between socioeconomic deprivation and poor survival in people with cancer participating in clinical trials.
“These findings suggest that 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,” say Joseph Unger (Fred Hutchinson Cancer Research Center, Seattle, Washington, USA) and colleagues.
“Policies to mitigate socioeconomic differences in cancer outcomes should emphasize access to cancer care services beyond initial therapy,” they propose.
The study included data for 41,109 participants from 55 phase 3 and large phase 2 clinical trials conducted by the SWOG Cancer Research Network between 1985 and 2012; participants had one of 24 different cancers, most commonly breast (42.6%), prostate (12.0%), colorectal (10.6%), and lung (6.6%) cancer.
To measure socioeconomic deprivation, the researchers linked patients’ residential zip codes to the Area Deprivation Index (ADI), which comprises 17 indicators reflecting diverse socioeconomic variables including employment, poverty, housing quality, and neighborhood-level measures of education.
In the primary Cox regression frailty model that adjusted for age, race, and sex, patients from the most socioeconomically deprived areas, defined as those in the highest ADI quintile (81–100%), were a significant 28% more likely to die within 5 years of follow-up than those from the most affluent areas (lowest ADI quintile, 0–20%).
The results were similar in a secondary model in which the researchers additionally accounted for the influence of insurance status, prognostic risk, and rural or urban residency, such that individuals living in the most deprived areas had a significant 22% increased risk for death relative to those living in the most affluent areas.
“There was a clear trend toward consistently increasing risk of death as the level of deprivation increased,” says the team, adding that the findings were similar for progression-free and cancer-specific survival.
Indeed, patients in the most deprived areas were a significant 20% and 27% more likely to have worse progression-free and cancer-specific survival, respectively, than those in the most affluent areas in the primary model.
“The observation that socioeconomic disparities in cancer outcomes persist despite access to treatment is consistent with the idea that low socioeconomic status represents a risk factor for poor health outcomes because of poor access to resources (including medical, technical, and financial resources),” the researchers write in the Journal of Clinical Oncology.
“In this setting, the receipt of protocol-guided therapy may provide beneficial initial access to guideline-based cancer care, but will not otherwise materially alter the tendency toward poor access to healthcare resources over the long term.”
Unger et al conclude: “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—determined using linked data sources such as Medicare claims—not reflected by protocol staging criteria.”
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