"Cancer clinical trials are how we move the field forward. As a result of patients not participating in clinical trials, it takes a lot longer and it's much more expensive to develop new therapies," said Dr. Dawn Hershman, who worked on the study.

"In this study we found one factor that contributes to that is patient income," Hershman, from Columbia University in New York, told Reuters Health.

Another reason to be worried about people not participating, according to the researchers, is that an underrepresentation of one group in a clinical trial may not make the findings applicable to the general population.

"We need to make sure that we make accommodations so that people in the trials reflect those who are in the general population and those who will be taking the drugs," said Dr. Jean Ford, who was not involved with the new study but has researched barriers to clinical trial participation.

For the new study, the researchers surveyed about 5,500 people who were recently diagnosed with breast, colorectal, lung or prostate cancer between 2007 and 2011.

The online survey asked whether or not the patients were offered to take part in a clinical trial and if they joined. It also collected information about the patient, such as sex, age, education and income.

Overall, 2,174 patients said they talked about clinical trials with their doctors. Of those, 45 percent were offered to join a trial, and about half said yes.

Ultimately, 9 percent of the original group took part in a trial.

The researchers then looked at which patients were most likely to say yes. They found 10 percent of patients making $50,000 or more per year enrolled in a trial, compared to 7.6 percent of those making less than that.

Hershman and her colleagues also found that difference in participation based on income applied to patients 65 years old and older, who don't normally worry about costs because they qualify for the federal insurance program Medicare.

That suggests, the researchers write in the Journal of Clinical Oncology, that the difference between poor and wealthy individuals goes beyond access to care.

OVERCOMING BARRIERS

There could be several reasons why poor patients are less likely to take part in clinical trials. For example, the researchers found doctors were less likely to offer them a spot in a trial - if one was discussed at all.

Also, they found low-income patients were more likely to be concerned about the costs associated with clinical trial treatments, compared to wealthier patients.

Those concerns, said Hershman, can go beyond paying for the treatment to patients being worried about gas money and taking time off work.

"There are numerous barriers, but where we are lacking is in developing interventions that actually work to recruit some of the groups that are underrepresented," Ford, the chair of the department of medicine at The Brooklyn Hospital Center, told Reuters Health.

"The bottom line is that if we are going to bring such populations into trials we are going to have to invest in the infrastructure to make it happen," said Ford.

SOURCE: bit.ly/UWIwlZ Journal of Clinical Oncology, online January 7, 2013.

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