Study: Colon cancer disparities point to healthcare utilization, not biology

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A lower follow-up exam rate for screen-detected colorectal abnormalities was noted among African-American individuals when compared with Caucasian individuals, and healthcare utilization may be to blame instead of biology in regard to the colorectal cancer racial disparity, according to a study published online this month in the Journal of National Cancer Institute.

Researchers from the National Cancer Institute (NCI), part of the National Institutes of Health, wrote: “It is unclear whether the disproportionately higher incidence and mortality from colorectal cancer among blacks compared with whites reflect differences in health-care utilization or colorectal cancer susceptibility.”

Led by Adeyinka O. Laiyemo, MD, from NCI’s division of cancer prevention, the researchers recruited 60,572 non-Hispanic Caucasian and African-American participants from the ongoing Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, a multi-center, randomized, controlled screening designed to evaluate the effect of screening on cancer mortality.

From November 1993 to July 2001, each participant underwent trial-sponsored screening flexible sigmoidoscopy (FSG) without biopsy at baseline in 10 geographically dispersed centers.

The researchers said that participants found to have polyps or mass lesions detected by FSG were referred to their physicians for diagnostic workup--the cost of which was not covered by the trial--and the records of these follow-up evaluations were collected and reviewed.

In addition, to rule out the possibility of other factors influencing the outcome of the study, the authors wrote, “we used log binomial modeling with adjustment for age, education, sex, body mass index, smoking, family history of colorectal cancer, colon examination within previous three years, personal history of polyps and screening center to examine whether utilization of diagnostic colonoscopy and yield of neoplasia differed by race.”

Laiyemo and colleagues found that among the 57,561 Caucasian participants, 13,743 or 23.9 percent had abnormal results, and of the 3,011 African-American participants, 767 or 25.5 percent yielded abnormal exams. Moreover, 9,944, or 72.4 percent of Caucasians, compared to 480, or 62.6 percent of African-Americans had diagnostic colonoscopy within one year following the abnormal FSG screening.

Of the participants that underwent diagnostic colonoscopy, a total of 156 colorectal cancers were diagnosed and there was no statistically significant difference by race in the prevalence of adenoma, advanced adenoma, advanced pathology in small adenomas or colorectal cancer, they wrote.

"Our research suggests that the biology of colorectal cancer may not differ by race, at least in the early stages of tumor development," said Laiyemo. "Instead, healthcare utilization differences among races may play a more important role in colorectal cancer disparities."

While the authors did not have direct information on the socioeconomic status of study participants, the overall educational level was lower for African-American participants than in Caucasian participants. The researchers believe that a lack of knowledge about cancer prevention among patients and a lack of cultural competence on the part of the health care providers could be potential barriers to healthcare utilization.

"This research suggests that targeting interventions toward increasing the use of screening among minority populations might go a long way toward reducing disparities in colorectal cancer," said senior author Christine Berg, MD, from the early detection research group in the NCI’s division of cancer prevention.