Increasing Participation in Research Trials
Two new studies have confirmed not only the importance of clinical trials for the development of promising new cancer treatments, but also the alarmingly low participation rates by cancer patients in these crucial research efforts.
For example, the results of a major new study on the anti-clotting drug heparin, published in the journal Proceedings of the National Academy of Sciences, appear to shed new light on its cancer-fighting potential.
Heparin is used to decrease the clotting ability of the blood, helping to prevent harmful clots from forming in blood vessels. It is sometimes referred to as a "blood thinner," although it does not actually thin the blood.
Dr. Ajit Varki and a team of investigators from the University of California at San Diego found that heparin might also reduce the ability of cancer cells to grow and multiply.
In a series of experiments with laboratory mice, the researchers found that heparin injections dramatically reduced the spread of colon cancer cells to the lungs. It appeared to do so by stripping substances called "mucins" from tumor cells, which in turn inhibited their ability to attach to roaming platelets. When this platelet-tumor adhesion was thwarted, so was platelet-facilitated metastasis.
Varki's team noted that heparin had been found to inhibit metastasis in earlier animal studies in which it was delivered intravenously, but not when it was delivered orally. They suggested that heparin's role in preventing platelet-tumor adhesion might explain why only IV injections into the bloodstream were successful.
As a result of their findings, the researchers called for immediate clinical trials to begin testing whether heparin might be equally effective in preventing cancer metastases in humans.
But while heparin may someday prove to be a powerful new anti-cancer drug, it faces a similar stumbling block to many new cancer medicines-an insufficient number of cancer patients enrolled in clinical trials.
This crisis was confirmed in a study by Dr. Primo Lara and colleagues at the University of California, Davis Cancer Center in Sacramento. They highlighted two reasons for this dearth of clinical trial enrollees: failure by physicians to refer patients to clinical trials, and patient reluctance to participate because of misperceptions and unfounded fears.
Writing in the Journal of Clinical Oncology, the researchers noted that 38 percent of 276 cancer patients who they surveyed said their doctor failed to mention clinical trials as a treatment option. When asked about this lack of communication, many of the doctors said they did not believe that protocols for the trials were available.
This is simply not the case, Lara's team noted, and they encouraged physicians to regularly check protocol lists rather than assume that none are available.
Physicians also hesitated to refer patients with "borderline status" to clinical trials. But the authors countered that "most cancer centers offer a variety of trials, including phase I trials that allow any type of advanced malignancy."
The researchers eventually asked 76 patients to consider participating in a clinical trial-however, only half (51 percent) agreed. When the decliners were asked why they would not participate, they cited a desire for more traditional (non-investigational) therapies, distance from the cancer center, and insurance concerns, among other reasons.
To counteract such concerns, the authors called for much more aggressive patient education programs-something that is long overdue.
A recent survey of nearly 6,000 cancer patients by Harris Interactive found that an alarming 85 percent were either unaware or unsure that they could participate in a clinical trial. Yet, three out of four of these patients "would have been willing to enroll had they known it was possible."
Close to a third of those patients who knew about clinical trials but declined to participate made their decision because they believed the new therapy would be less effective than "the standard treatment."
Similarly, another third feared that they might receive an inactive placebo rather than the treatment under study. Twenty-two percent feared being treated "like a guinea pig," and 20 percent feared the cost would not be covered by their insurance.
Yet, 93 percent of the patients who had actually participated in clinical trials said their overall experience was "positive," and three-fourths said they "would recommend participation to someone else with cancer."
SOURCES:
Proceedings of the National Academy of Sciences, March 13, 2001; 98:3352-3357
Journal of Clinical Oncology, March 15, 2001; 19:1728-1733
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