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Race in Colorectal Cancer Screening Strategies: A Solid Determinant Factor or a “Moving Target”?

2014; Elsevier BV; Volume: 147; Issue: 6 Linguagem: Inglês

10.1053/j.gastro.2014.06.044

1528-0012

Faraz Bishehsari,

Global Cancer Incidence and Screening

I read with great interest the study by Lieberman et al1Lieberman D. et al.Gastroenterology. 2014; 147: 351-358Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar on effect of race/ethnicity and sex on risk of large polyps in average-risk individuals. This interesting study provides strong evidence that the “one-size-fits-all” strategy for colorectal cancer (CRC) screening is not optimal. The increased polyp rates by age, mirroring the linear age-specific incidence rate curves for CRC incidence reflects a logical epidemiologic consequence of the adenoma-to-carcinoma sequence. The paper elegantly confirms the effect of gender on the adenoma rates, repeatedly shown by prior studies.2Ferlitsch M. et al.JAMA. 2011; 306: 1352-1358Crossref PubMed Scopus (201) Google Scholar Based on the observation of differential large adenoma rates between racial groups, the authors proposed that race should be taken into account in customization of a risk-based strategy in CRC screening. Although at first glance this seems to be a rational interpretation of the presented data, I wish to draw attention to a few limitations of such a conclusion. Since the mid 1980s, despite an overall decrease in incidence of CRC, the disease rates have remained higher than whites.3American Cancer SocietyColorectal cancer facts & figures 2011–2013. American Cancer Society, Atlanta2011Google Scholar The slower trend in reduction of CRC incidence among blacks was at least partly attributed to their relatively restricted access to screening programs. The results of the current study, however, indicate higher rates of precancerous lesions in “average-risk” blacks compared with whites. The observed racial/ethnical disparities may be more related to differential exposures than to genetic makeup of a race/ethnicity. Several studies have demonstrated a dramatic rise in CRC rates in originally low-risk ethnic groups when they migrated to high-risk areas, highlighting environmental factors as dominant etiologic elements in majority of CRCs.4Bishehsari F. et al.World J Gastroenterol. 2014; 20: 6055-6072Crossref PubMed Scopus (161) Google Scholar Factors associated with risk of colorectal neoplasms such as dietary intake and lifestyle, among others, can show racial pattern as well, and are proposed to have phenotypic consequences on the disease. Blacks are shown to have less access to healthy foods and consume a lower quality diet.5Franco M. et al.Am J Clin Nutr. 2009; 89: 897-904Crossref PubMed Scopus (194) Google Scholar Higher prevalence for diabetes in blacks versus whites, may partly explain their higher rates of proximal CRCs.6Irby K. et al.Cancer Epidemiol Biomarkers Prev. 2006; 15: 792-797Crossref PubMed Scopus (109) Google Scholar Exposure to CRC risk factors vary substantially even within 1 ethnicity and may account for an almost 2-fold geographical variation of CRC incidence in blacks among different states.3American Cancer SocietyColorectal cancer facts & figures 2011–2013. American Cancer Society, Atlanta2011Google Scholar The current study encompasses 84 practices throughout the country, and it is possible that adenoma rates, too, vary among centers/states reflecting differential risk factors exposures. Without excluding such a variation, one cannot exclude that a disproportionate contribution of each ethnicity from different locations to the pool of data has not accounted for part of the observed racial dissimilarities. Therefore, in the absence of testing for environmental CRC risk factors, adjustment of the analysis for the location of the screening program to evaluate the racial effect independent from the geography would have strengthened the authors’ results. Of note, recent reports from single states showed similar adenoma prevalence in both blacks and whites7Corley D.A. et al.Clin Gastroenterol Hepatol. 2013; 11: 172-180Abstract Full Text Full Text PDF PubMed Scopus (144) Google Scholar and Hispanics and whites.8Thoma M.N. et al.Gastrointest Endosc. 2013; 77: 430-435Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar It would be interesting to see if the pattern of racial disparities observed by Lieberman et al1Lieberman D. et al.Gastroenterology. 2014; 147: 351-358Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar remains similar across geographic locations. Race can be a surrogate for several environmental risk factors for CRC that are usually individual, although these factors may cluster in households or ethnicities. The authors may agree that the group of 45-year-old, cigarette smoking, morbidly obese whites who consume a high meat diet may not enjoy a racial advantage for the risk of large adenoma, compared with a similar age group of nonsmokers, lean, and physically active black individuals who eat “healthy.” Moreover, the pattern of exposure could be dynamic within 1 race, and can alter in response to lifestyle changes, making a racial-based strategy a “moving target.” Although using race/ethnicity as a proxy for environmental CRC risk factors may seem rational at the epidemiologic level, its implications in screening recommendations at an individual level may not be accurate. Therefore, it seems more appropriate to think of race as a social characteristic that reflects the environmental risk factors for an individual rather than a biological definition of an ethnicity when implementing personalized screening colonoscopy strategies. Race, Ethnicity, and Sex Affect Risk for Polyps >9 mm in Average-Risk IndividualsGastroenterologyVol. 147Issue 2PreviewColorectal cancer risk differs based on patient demographics. We aimed to measure the prevalence of significant colorectal polyps in average-risk individuals and to determine differences based on age, sex, race, or ethnicity. Full-Text PDF ReplyGastroenterologyVol. 147Issue 6PreviewBishehsari notes that geography and environmental risk factors could influence the risk of colon neoplasia in race and ethnic subgroups. There is documented geographic variation in the risk for colorectal cancer (CRC) within the United States, as pointed out by Bishehsari, which may be owing to many factors, and we agree that this is a subject worthy of further study. Full-Text PDF