JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION VOL. 100, NO. 3, MARCH 2008 291 o r i g i n a l c o m m u n i c a t i o n introduction M inority populations in the United States, espe- cially blacks and Hispanics, have historically been underrepresented among participants in clinical trials. 1,2 Adequate representation of these groups in clinical trials is important in order to insure equitable distribution of the risks and benefits of participation in research, and in order to enable the detection of possible interactions of treatment effect by race/ethnicity based on biological, social or cultural factors related to race. 1-3 Such inclusion is particularly important when a minor- ity group has an increased burden of the disease being studied. Recently, efforts have been made to increase minority representation in clinical research, especially phase-III trials. In 1990, the NIH issued policy guide- lines on the inclusion of minorities (and women) in clin- ical research. These guidelines were updated in 1993 and 2001, with the current guidelines stating that minor- ity groups and their subpopulations must be included in all NIH-supported biomedical research projects involv- ing human subjects, unless a clear and compelling rationale is given showing that such inclusion would be inappropriate. 4 The guidelines further support efforts at the study planning stage to ascertain whether there is evidence of significant differences in the effect of the intervention among racial and ethnic subgroups of the population and, if so, to design the study so that such differences can be validly assessed. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial is an ongoing, large, multicenter, randomized controlled trial designed to evaluate the mortality benefit of screening for these four cancers in © 2008. From the Division of Cancer Prevention, National Cancer Institute, Bethesda, MD (Pinsky, Marcus, Gohagan); Henry Ford Health System, Detroit, MI (Ford, Lamerato); University of Colorado Health Sciences Center, Denver, CO (Gamito, Tenorio); University of Alabama at Birmingham, Birmingham, AL (Higgins); and Pacific Health Research Institute, Honolulu, HI (Jenkins). Send correspondence and reprint requests for J Natl Med Assoc. 2008;100:291– 298 to: Dr. Paul Pinsky, 6130 Executive Blvd., EPN 3064, Bethesda, MD 20892; phone: (301) 402-6480; fax: (301) 402-0816; e-mail: pp4f@nih.gov Background: Minority populations in the United States, espe- cially blacks and Hispanics, are generally underrepresented among participants in clinical trials. Here, we report the experience of enrolling ethnic minorities in a large cancer screening trial. Methods: The Prostate, Colorectal, Lung and Ovarian (PLCO) Cancer Screening Trial is a multicenter randomized trial designed to evaluate the effectiveness of screening for the PLCO cancers. Subjects were recruited at 10 U.S. centers between 1993 and 2001. One screening center had a major special recruitment effort for blacks and another center had a major special recruitment effort for Hispanics. Results: Among almost 155,000 subjects enrolled in PLCO, minority enrollment was as follows: black (5.0%), Hispanic (1.8%) and Asian (3.6%). This compares to an age-eligible population in the combined catchment areas of the PLCO centers that was 14.0% black, 2.9% Hispanic and 5.4% Asian, and an age-eligible population across the U.S. that was 9.5% black, 6.5% Hispanic and 3.0% Asian. About half (45%) of His- panics were recruited at the center with the special Hispanic recruitment effort. Seventy percent of blacks were recruited at two centers; the one with the major special recruitment effort and a center in Detroit whose catchment area was 20% black among age-eligibles. Blacks, Hispanics and (non- Hispanic) whites were all more highly educated, less likely to currently smoke and more likely to get regular exercise than their counterparts in the general population. Conclusion: Significant efforts were made to recruit racial/ ethnic minorities into PLCO, and these efforts resulted in enrollment levels that were comparable to those seen in many recent cancer screening or prevention trials. Blacks and Hispanics were nonetheless underrepresented in PLCO compared to their levels among age-eligibles in the overall U.S. population or in the aggregate PLCO catchment areas. Key words: African Americans n Latinos n cancer n clinical investigation n screening Enrollment of Racial and Ethnic Minorities in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial Paul F. Pinsky, PhD; Marvella Ford, PhD; Eduard Gamito; Darlene Higgins; Victoria Jenkins, MEd; Lois Lamerato, PhD; Sally Tenorio; Pamela M. Marcus PhD; and John K. Gohagan, PhD