After people pointed out that clinical trials of white men might not represent the population at large, in 1993 Congress passed a law that encourages NIH-funded clinical trials to include women and minorities. To find out if the law is working, researchers at Yale looked at enrollment in cancer trials.

What the researchers wanted to know: How diverse are the patients enrolled in cancer trials?

What they did: The researchers used the list of all patients enrolled in clinical trials funded by the National Cancer Institute, which includes information about age, sex, and race/ethnicity. For this study, they just looked at the 75,215 people enrolled in trials for the four cancers that killed the most people during the study period: breast, colorectal, lung, and prostate cancer. The patients' characteristics were compared with the National Cancer Institute's data on who gets cancer.

What they found: Blacks and Hispanics were considerably less likely than whites to be enrolled in cancer trials; while 3.3 percent of whites with breast cancer were enrolled in a trial, only 2.4 percent of Hispanics and 2.5 percent of blacks were (a statistically significant difference). People over 65 were less likely to be enrolled than younger people, and for colorectal cancer and lung cancer—the only cancers of the four studied that both men and women get—women were less likely to be enrolled than men. (But younger men and women were equal.)

What it means to you: It may be dangerous to apply the results of clinical trials to people who are underrepresented in them, the authors write.

Caveats: The study doesn't included trials funded by anyone other than the National Cancer Institute—for example, drug companies. Since they only studied four cancers, the results may not be representative.

Find out more: National Cancer Institute cancer surveillance program http://www.seer.cancer.gov/

National Cancer Institue database of clinical trials http://www.cancer.gov/search/clinicaltrials/

The National Library of Medicine's list of private and government-funded clinical trials (not just cancer) http://clinicaltrials.gov/

Read the article: Murthy, V.H., Krumholz, H.M., and C.P. Gross. "Participation in Cancer Clinical Trials: Race-, Sex-, and Age-Based Disparities." Journal of the American Medical Association. June 9, 2004, Vol. 291, No. 22, pp. 2720–2726.

Abstract online: http://jama.ama-assn.org/