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. 2010 Mar;56(3):229-38.

Dietary interventions for fecal occult blood test screening: systematic review of the literature

Gerald Konrad  1
Affiliations

Dietary interventions for fecal occult blood test screening: systematic review of the literature

Gerald Konrad. Can Fam Physician. 2010 Mar.

Abstract
in English, French

Objective: To determine whether dietary restrictions enhance the specificity of guaiac-based fecal occult blood tests (FOBTs) when screening for colorectal cancer.

Data sources: PubMed-MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases were searched.

Study selection: English-language case series, cohort studies, randomized controlled trials (RCTs), and meta-analyses were selected. Studies that did not include dietary manipulation or the use of guaiac-based FOBTs available in North America were excluded.

Synthesis: Ten case series, 5 cohort studies, 4 RCTs, and 1 meta-analysis were critically appraised. All studies used Hemoccult, Hemoccult II, or Hemoccult SENSA tests. Data from case series involving challenge diets showed no increase in positive FOBT results from high-peroxidase vegetables, but results varied with red-meat challenges depending on the amount of meat consumed and the test used. Case series, cohort studies, and RCTs comparing FOBT results during restricted versus unrestricted diets consistently showed no differences in positive FOBT results.

Conclusion: Most of the evidence evaluating the effect of dietary restrictions on FOBT results is dated and of suboptimal quality. However, 4 RCTs and a meta-analysis of these data do not support dietary restrictions when screening for colorectal cancer. Because patient adherence can be an issue with FOBTs, and dietary restrictions can affect adherence in some populations, it is reasonable to abandon these recommendations without fear of substantially affecting specificity.

OBJECTIF: Déterminer si les restrictions alimentaires accroissent la spécificité des tests au gaïac pour la recherche du sang occulte dans les selles (RSOS) lors du dépistage du cancer colorectal.

SOURCES DES DONNÉES: On a consulté PubMed-MEDLINE, le Cumulative Index to Nursing and Allied Health Literature et la base de données Cochrane.

CHOIX DES ÉTUDES: On a retenu les séries de cas, études de cohorte, essais cliniques randomisés (ECR) et méta-analyses de langue anglaise. Les études qui n’incluaient pas de modification alimentaire ou qui n’utilisaient pas les tests au gaïac pour la RSOS disponibles en Amérique du Nord ont été exclues.

SYNTHÈSE: On a fait une évaluation critique de 10 séries de cas, 5 études des 4 ECR et 1 méta-analyse. Toutes les études utilisaient les tests Hemocult, Hemocult II ou Hemocult SENSA. Les données des séries de cas portant sur des régimes types n’ont montré aucune augmentation de résultats positifs pour la RSOS avec les légumes à haute teneur en peroxydase, mais les résultats variaient pour les régimes riches en viande, selon la quantité de viande consommée et le test utilisé. Les séries de cas, études de cohorte et ECR qui comparaient les résultats de la RSOS en présence d’un régime avec ou sans restriction montraient invariablement l’absence de différence du taux de résultats positifs.

CONCLUSION: Les données concernant l’effet des restrictions alimentaires sur les résultats de la RSOS sont pour la plupart désuètes et de qualité sub-optimale. Toutefois, 4 ECR et une méta-analyse de ces résultats ne supportent pas l’utilisation de restrictions alimentaires lors du dépistage du cancer colo-rectal. Puisque l’observance du patient peut être problématique lors de la RSOS et que les restrictions alimentaires peuvent affecter l’observance dans certaines populations, il paraît raisonnable d’abandonner ces recommandations sans crainte de modifier la spécificité du test.

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Figures

Figure 1.
Figure 1.
Outcome of screening by FOBTs in a case series investigating the effects of dietary restriction on FOBT results
Figure 2.
Figure 2.
Outcome of screening by FOBTs in subjects with any positive results accepting further testing
Figure 3.
Figure 3.
Outcome of screening by FOBT in a case series examining the effects of the number of positive smear results on the need for dietary restrictions when retesting
See this image and copyright information in PMC

References

    1. Canadian Cancer Society, National Cancer Institute of Canada . Canadian cancer statistics 2007. Toronto, ON: Canadian Cancer Society, National Cancer Institute of Canada; 2007.
    1. Hewitson P, Glasziou P, Watson E, Towler B, Irwig L. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (Hemoccult): an update. Am J Gastroenterol. 2008;103(6):1541–9. Epub 2008 May 13. - PubMed
    1. Pignone M, Campbell MK, Carr C, Phillips C. Meta-analysis of dietary restriction during fecal occult blood testing. Eff Clin Pract. 2001;4(4):150–6. - PubMed
    1. Hemoccultfobt.com [website] Patient instructions Hemoccult II slide (test card) Fullerton, CA: Beckman Coulter Inc; 2005. Available from: http://hemoccultfobt.com/docs/English461860.C.pdf. Accessed 2010 Feb 2.
    1. Beckmancoulter.com [website] Hemoccult SENSA product instructions. Fullerton, CA: Beckman Coulter Inc; 2002. Available from: www.beckman-coulter.com/literature/ClinDiag/462489-E.pdf. Accessed 2010 Feb 2.

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