Awarded RFA Grant 2009
Dr Loïc Le Marchand, M.D., Ph.D.
Epidemiology Program, Cancer Research Center of Hawaii
University of Hawaii, USA
Project title
Validation of the Hair as a Tissue to Biomonitor PhIP, a Carcinogenic Heterocyclic Aromatic Amine.
Scientific abstract
Professor Le Marchand will validate the use of hair to monitor chronic exposure to the carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a heterocyclic aromatic amine (HAA) formed in cooked meat.
Short-term urinary biomarkers of PhIP exist; however, these are transient and only capture the preceding 24 hours of exposure. For individuals who chronically (but intermittently) consume cooked meats, urinary PhIP can go undetected, and these individuals can be misclassified.
A biomarker of long-term exposure is critically needed to advance the field and confirm the carcinogenic effect of PhIP in humans.
Professor Le Marchand’s group has recently developed a method to measure PhIP in hair, the levels of which varied greatly among subjects. In the new WCRF-funded project he will examine how dietary exposure to PhIP, cytochrome P450 1A2 activity and hair colour affect hair PhIP level. More specifically, he will validate the biomarker in two feeding studies using already established protocols; and describe its epidemiologic characteristics in a completed study of adenoma.
The proposed studies will enable us to determine the reliability of hair PhIP level as a biomarker of dietary intake and health risk, and the practicality of using it in large epidemiological studies to study the association of HAAs with disease risk.
Project plain language abstract
We propose to validate the use of hair as a tissue in which to assess long-term human exposure to the cancer-causing chemical, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a heterocyclic aromatic amine (HAA) formed in cooked meat. Short-term urinary biomarkers of PhIP exist; however, these are short-lived and only capture the preceding 24 hours of exposure. For individuals who chronically but intermittently consume cooked meats, urinary PhIP can be undetected. A biomarker of long-term exposure is critically needed to advance the field and confirm the cancer-causing effect of PhIP in humans.
We recently developed a convenient method to measure PhIP in hair, the levels of which varied greatly among subjects. We will examine how dietary exposure to PhIP, the activity of liver metabolic enzyme (CYP1A2) and hair color affect hair PhIP level. We propose to: 1) validate the biomarker in two feeding studies using already established protocols; and 2) describe its epidemiologic characteristics in a completed study of adenoma. The proposed studies will enable us to determine the reliability of hair PhIP level as a biomarker of dietary intake and health risk, and the practicality of using it in large epidemiological studies to study the association of HAAs with disease risk.
“Whether heterocyclic amines in well-done meat increase risk of certain cancers in humans, as they do in experimental animals, remain unresolved despite many years of research. This is probably because exposure to these compounds are difficult to measure with questionnaires.
With this new grant, we hope to show that measuring these compounds in hair provide a valid marker of long-term exposure. Such a convenient biomarker would be very useful in epidemiological studies to confirm or exclude any important link to cancer.”
Loïc Le Marchand, M.D., Ph.D.
