Trial Information

Screening and Risk Factors of Colon Neoplasia

Colorectal carcinoma is currently the second most common fatal cancer in the United States,
and is largely preventable through the use of screening in the asymptomatic population.
Although colonoscopy is considered to be the most accurate 'gold standard' screening test,
there are a significant proportion of eligible patients who decline colonoscopy or in whom
colonoscopy is not readily available. More recently, testing for aberrant molecular/genetic
markers in stool DNA (sDNA) is emerging as a promising alternative to colonoscopy, and some
professional society guidelines have endorsed the use of sDNA testing in the early detection
of colorectal cancer. However, despite some guidelines that endorse sDNA testing primarily
for the detection of colorectal cancer, data on the efficacy of sDNA testing for advanced
adenomas, and hence prevention of colorectal cancer, are limited.

Colon carcinogenesis is a multifactorial and multistep process that involves both genetic
and environmental influences. Diet clearly plays an important role. However, despite
extensive research, there has been limited success in identifying such specific dietary and
nutritional factors. In particular, a number of within-population studies, including several
randomized trials, have yielded conflicting results and cast serious doubt on the
hypothesized central role of dietary fat and fiber in colon carcinogenesis. In contrast,
there is increasing evidence relating colon neoplasia to obesity, type 2 diabetes and
related metabolic abnormalities. These results, together with the marked and consistent
similarities in the dietary and lifestyle risk factors for type 2 diabetes and colon
neoplasia have led to the notion that insulin resistance resulting from energy imbalance
(excess energy intake, physical inactivity, and obesity) may be the underlying link between
these two entities. Indeed, the insulin resistance-colon neoplasia hypothesis could account
for many of the dietary and lifestyle risk factors of colon neoplasia and for its high
incidence in Western countries. The fact that the incidences of obesity, insulin resistance
syndrome, and type 2 diabetes are escalating at epidemic pace in the Western societies makes
the exploration of the insulin resistance-colon neoplasia hypothesis a subject of pressing
priority.

A Food Frequency Questionnaire (FFQ), a Meat Preparation Questionnaire (MPQ), and a Physical
Activity Questionnaire (PAQ), all developed at the University of Arizona Cancer Center will
be used to collect dietary and physical activity data.The FFQ, MPQ and PAQ questionnaires
will be self-administered by each subject according to detailed written instructions, and
they are mailed to the participant with the consent forms. Subjects will be asked to donate
whole blood and urine samples on the day of routine colonoscopy exams. These samples will
be looked at for disease markers. Stool samples will be collected to evaluate its use at
detecting colon polyps using the sDNA Test and 2 FIT tests (fecal immunochemical test).