Lower income cancer patients less likely to join clinical trials

Cancer patients with annual household incomes below $50,000 were less likely to participate in clinical trials than higher income patients and were more likely to be concerned about how to pay for clinical trial participation, according to a large study by the SWOG (formerly the Southwest Oncology Group) cancer research cooperative group.

Led by the Hutchinson Center's Dr. Joseph Unger of the SWOG Statistical Center in the Public Health Sciences Division, the study surveyed 5,499 patients who registered with an online treatment decision tool. The findings are being presented at the annual meeting of the American Society for Clinical Oncology in Chicago this week.

The researchers, including Dr. Carol Moinpour (also of PHS), found 7.6 percent of survey takers with an annual income below $50,000 reported participating in clinical trials, while 10 percent of those with incomes of $50,000 or more said they took part.

Patient and researcher concerns

Lower levels of participation are a concern on at least two fronts, Unger said. "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," he said.

On a broader scientific level, Unger said 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 said that although past research has shown that patient care costs for clinical trials are not appreciably higher than for nontrial 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 suggested that further research is needed to identify the specific cost concerns that may be limiting participation for lower income patients.

Study used actual patient incomes

Unger said this is the largest national study to use actual patient incomes and to also account for other medical conditions. Comorbidities are an important 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.

Because income data are not generally collected from patients when they start treatment, previous studies looking 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.

SWOG is one of the five cooperative groups that together comprise the National Cancer Institute'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 Center houses SWOG's statistical center.

The National Cancer Institute and NexCura funded the study.

[Adapted from a SWOG news release]