Among the various age groups, Tejeda et al., (1996) found that overall, younger patients tend to be heavily represented in Clinical Trials Cooperative Groups, because slightly less than half of trial participants are under age 50 years, even though more than 85 percent of cancer diagnoses occur among people 50 years of age or older. Within age groups, the level of accrual of African-American and Hispanic patients appeared in most instances to be proportional to the incidence or slightly below the incidence of cancer in these populations. Among African-American and Hispanic patients ages 0 to 19 years, the level of enrollment (11.0 and 12.0 percent respectively) was very close to rates of incidence (12.4 and 11.9 percent, respectively); the same held true within the 20- to 49-year-old age group (10.6 and 4.8 percent enrollments for African Americans and Hispanics, respectively, compared to incidence rates of 11.4 and 6.0 percent, respectively) and the group consisting of those 50 years of age and older (8.5 and 2.5 percent enrollment for African Americans and Hispanics, respectively, compared to incidence rates of 9.1 and 2.9 percent, respectively).
When accrual was examined by specific cancer sites (leukemia and breast, colorectal, lung, and prostate cancer), Tejeda et al., (1996) found that, with a few exceptions, the level of ethnic minority enrollment in Clinical Trials Cooperative Groups generally was proportional to or greater than the expected incidences. Enrollment of African Americans in trials involving colorectal cancer (8.4 percent enrollment) and prostate cancer (9.8 percent enrollment) lagged slightly behind the incidence rate among this group (9.4 percent of cases of colorectal cancer and 11.1 percent of cases of prostate cancer among African Americans). Similarly, the level of enrollment of Hispanics in trials involving lung cancer (1.4 percent enrollment) also lagged slightly behind the incidence (2.2 percent). The greatest disparities in accrual were observed among African Americans ages 20 to 49 years with leukemia (9.4 percent enrollment compared with 12.4 percent incidence), colorectal cancer (10.2 percent enrollment compared with 15.7 percent incidence), and lung cancer (17.2 percent enrollment compared with 20.4 percent incidence) and among Hispanics ages 20 to 49 years with lung cancer (1.8 percent enrollment compared with 3.2 percent incidence).
The analysis of Tejeda et al., (1996), however, did not examine cancer incidence among Asian-American, Alaska Native; and American Indian populations in determining the proportionality of accrual patterns because of the small number of cases of cancer among these groups in the SEER program database. Similarly, the study does not report on the proportionality of accrual of low-income, low-literacy-level, rural, or otherwise medically underserved populations, presumably because these data are not reported in the SEER program registry (see Chapter 2).
NCI provided to the committee raw data and percentages of total enrollment