More than half of all cancer patients do not participate in clinical trials because none are available for their cancer type or stage at their institution, according to a meta-analysis of cancer clinical trials that examined the trial decision-making pathway.

“This is the first effort to systematically both define and quantify domains of clinical trial barriers using a meta-analytic approach,” wrote lead author Joseph M. Unger, PhD, of the Fred Hutchinson Cancer Research Center in Seattle and his coauthors in the Journal of the National Cancer Institute.

To identify trials that addressed barriers to enrollment, Dr. Unger and his colleagues conducted a literature search using the PubMed, Google Scholar, Web of Science, and Ovid Medline databases. The search returned 7,576 unique results, of which they reviewed 38 full articles and eventually decided on 13 studies comprising 8,883 patients. Nine of the studies were focused on academic care settings, and four were focused on community care settings; seven examined patient decision-making patterns in all types of cancers, while the others focused on breast cancer only (n = 2), lung cancer only (n = 2), prostate cancer only (n = 1), and cervix/uterine cancers (n = 1).

Their analysis found that, for 55.6% of patients, no trial was available for their cancer type and stage (95% confidence interval, 43.7%-67.3%). In addition, 21.5% (95% CI, 10.9%-34.6%) were not eligible for an available trial, and 14.8% (95% CI, 9.0%-21.7%) did not enroll; only 8.1% (95% CI, 6.3%-10.0%) enrolled in a trial. Academic sites (15.9%, 95% CI, 13.8%-18.2%) saw much higher rates of participation than community sites (7.0%, 95% CI, 5.1%-9.1%; P less than .001).

The authors acknowledged their study’s limitations, including details on trial availability not being available for all analyzed studies. In addition, several of the studies relied on selected cancer types instead of sampling a representative set of cancers. Finally, these studies may have oversampled research-oriented sites, which would mean “the actual overall trial participation rate may be lower than we estimated.”

The study was supported by the National Cancer Institute. The authors reported no conflicts of interest.

SOURCE: Unger JM et al. J Natl Cancer Inst. 2019 Feb 19. doi: 10.1093/jnci/djy221.