Even with access to a clinical trial, cancer patients living in the poorest areas of America are nearly 30% more likely to die from their disease than the richest patients, according to results from the SWOG Cancer Research Network study.
Published in the Journal of Clinical OncologyThe results illustrate the persistently harmful effects of poverty on health and life expectancy, says study director Joseph Unger, PhD, a SWOG researcher and biostatistician at the Fred Hutchinson Cancer Research Center.
“Participating in a clinical trial guarantees consistent, high-quality care that should help improve outcomes for people with cancer,” said Unger. “It is surprising and dismaying to learn that, although studies benefit all patients, the poorest patients are still much more likely to die of cancer. The inequality persists. “
At SWOG, a cancer clinical trial group funded by the National Cancer Institute, part of the National Institutes of Health, Unger is building a high-profile work that examines the causes and effects of health differences in cancer patients. In 2018, he published results of a study that showed that differences in survival rates between cancer patients in rural and urban areas are significantly reduced when patients are enrolled in a clinical trial. With this new work, Unger wanted to investigate the connection between socio-economic deprivation and outcomes in cancer patients for the first time.
To investigate the relationship, Unger and his team analyzed data from 41,109 patients who had participated in 55 phase III and large phase II studies carried out by SWOG between 1985 and 2012. Patients in the studies were diagnosed with any major cancer type and at different stages in the cancer progression.
The team used the patient’s zip codes and linked them to the Area Deprivation Index, a measure of the socio-economic ranking of US neighborhoods. The team categorized patients into five categories, ranging from “most disadvantaged” to “most affluent”. The team also examined patient outcomes in terms of overall survival and progression-free survival. Finally, the team investigated cancer-specific survival or whether and when test patients specifically died from their disease.
The result: the poorest patients live the shortest. Compared to trial patients in the most affluent areas, these patients had a 28% increased risk of death. The same pattern was found for progression-free and cancer-specific survival. Patients in the poorest areas always fared worst, even after considering possible demographic, clinical, and geographic variables that could affect their health and longevity.
The factors causing the differences are many, according to Unger, ranging from a lack of access to good medical care and the money to get it, to an increased risk of smoking, obesity, and other factors that can lead to poor health. His results suggest that the type of guideline-based cancer patients treated in a clinical trial can eradicate about half of the negative effects of poverty.
Edited by Gary Cramer