ATLANTA—It is a phrase heard increasingly during scientific presentations: "Trial stopped early due to lack of accrual." Clinical trials may be running out of volunteers, according to a report at the American Society of Clinical Oncology 2006 meeting (abstract 6016).

In a review of breast, lung, and prostate cancer studies currently accruing patients, lead investigator Jennifer Tam-McDevitt, PharmD, PhD, of the Geriatric Oncology Consortium, Baltimore, and her colleagues found that 238,000 patients are needed to fulfill enrollment aims for these studies. For breast cancer, the number of patients needed represents a significant percentage of the breast cancer incidence for 2005. Currently, only about 10% of cancer patients are enrolled in US trials. With more drugs in the pipeline and more clinical trials being conducted, demand for participants may be outpacing the current "supply," she said.

The researchers derived data from the Clinical Trials database maintained by the NIH (www.clinicaltrials.gov). This database was selected because it has been proposed as the mandated repository for clinical trials information. Over a 2-month period, the database was mined for all active US trials recruiting patients for phase I, I/II, II, and III clinical trials in breast, lung, and prostate cancers.

The researchers found 290 breast, 212 lung, and 177 prostate cancer trials; the number of patients needed for the trials was 151,311 (breast), 33,498 (lung), and 53,181 (prostate). These figures represent 19.4% to 71.6% of the American Cancer Society incidence estimates of the studied tumors. About half of the studies (51%) were phase II, and about half the patients had advanced disease.

"Although many studies have an anticipated enrollment period over several years, the number of trial participants needed to complete these studies is quite daunting," Dr. Tam-McDevitt said, adding that the results are likely underestimates, as not all studies currently enrolling patients may be included in the NIH registry, and not all studies in the database specified the recruitment goal.

"It is clear that, given the current trial participation rate, demand has outpaced supply," she said. "The number of anticancer agents in the pipeline heading into clinical trials will continue to fuel the competition for research patients."

One solution to the problem, she said, could be rationing patients to important studies. "But more important, we support the creation of a national task force to facilitate better communication with the medical community, the government, the public, and the industry, to address current challenges to study enrollment and retention," she said.

Patients Unaware of Trials