ANN ARBOR, MICH. -- Cancer patients with annual household incomes below $50,000 were less likely to participate in clinical trials than patients with annual incomes of $50,000 or higher, and were more likely to be concerned about how to pay for clinical trial participation. This is the conclusion of a large study by the SWOG cancer research cooperative group that will be presented at the annual meeting of the American Society for Clinical Oncology (ASCO) in Chicago this week.

The study was a collaboration between SWOG, supported largely by the National Cancer Institute (NCI), and NexCura, which until the recent sale of that company had run an online treatment decision tool that many cancer advocacy organizations made available to patients via their websites.

Led by Joseph M. Unger, M.S., Ph.C., of the SWOG Statistical Center and the Fred Hutchinson Cancer Research Center in Seattle, the study surveyed 5,499 patients who registered with NexCura's treatment decision tool.

In the end, 7.6 percent of survey takers with an annual income below $50,000 reported participating in clinical trials, while 10.0 percent of those with incomes of $50,000 or more said they took part.

Lower levels of participation are concerning on at least two fronts, says Unger. "From the patient perspective, since clinical trials offer state of the art therapy, lower income patients may not have equal access to this important medical resource."

On a broader scientific level, Unger argues that increasing participation rates of lower income patients in clinical trials would give doctors and researchers greater confidence that the results of those trials apply to patients across the income spectrum. In addition, with more patients participating in clinical trials, trials could be done more quickly, ultimately speeding the development of new treatments for cancer patients.

The researchers found that lower income patients were more likely to be concerned about how to pay for the care they would receive as part of a clinical trial. Unger proposes that although past research has shown that patient care costs for clinical trials are not appreciably higher than for non-trial treatments, lower income patients may still be more concerned about co-pays and co-insurance than higher income patients. Also, lower income patients may be more affected by the indirect or hidden costs of clinical trial participation, such as having to take time off work to go to a clinic visit. The researchers suggest that further research is needed to identify the specific cost concerns that may be limiting participation for lower income patients.

Because income data are not generally collected from patients when they start treatment, previous studies that looked at socioeconomic status and trial participation often included surrogate measures to infer income level; for example, median income level from the patient's zip code region was used to estimate individual patient income. Those earlier studies hinted at this correlation, but tended to be less reliable as evidence.

Unger notes that, "This is the biggest study to use patient-level income on a national level that also accounts for patient medical conditions." He emphasizes the importance of the comorbidity factor because lower income patients are more likely to suffer from a range of health conditions that might limit their eligibility for trials. This study was able to control for these differences in health status, yet the difference in participation rates by income level remained.

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Additional authors: D Hershman, KS Albain, C Moinpour, J Petersen, K Burg, JJ Crowley

Funding: National Cancer Institute; NexCura

Disclosure: None

Reference: Unger, JM et al. "Patterns of Decision-Making about Cancer Clinical Trial Participation among the Online Cancer Treatment Community: A collaboration between SWOG and NexCura®." American Society of Clinical Oncology Annual Meeting, June 1-5, 2012, Chicago, abstract No. 6009.

About the SWOG clinical trials network:

SWOG is one of the five cooperative groups that together comprise the National Cancer Institute's (NCI's) National Clinical Trials Network. The group designs and conducts multidisciplinary clinical trials to improve the practice of medicine in preventing, detecting, and treating cancer, and to enhance the quality of life for cancer survivors. The more than 4,000 researchers in the group's network practice at more than 500 institutions, including 22 of the NCI-designated cancer centers as well as cancer centers in almost a dozen other countries. Formerly the Southwest Oncology Group, SWOG is headquartered at the University of Michigan in Ann Arbor (734-998-7140) and has an operations office in San Antonio and a statistical center in Seattle. Learn more at swog.org.

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