Sonja Berndt

NCI, DCEG, OEEB

PLCO (Learn more about this study)

2008-0054

Nov 10, 2008

Examining Questionnaire-Based Risk Factors for Recurrent Colorectal Adenoma in the PLCO Cancer Screening Trial: Fruits and Vegetables, Fiber, and Family History

In a coordinated series from PLCO intramural and extramural investigators of 19 published manuscripts on risk of prevalent colorectal adenoma in the PLCO Trial, risk evaluations were reported for dietary fiber, carbohydrate intake and glycemic load, meat cooking practices and the meat mutagen PhIP, dietary calcium, a gene variant in the calcium-sensing receptor, serum selenium, hormone replacement therapy, insulin-like growth factors, tobacco use, and selected genetics factors. The PLCO Colon Committee has completed a data collection on recurrent polyps in PLCO Trial participants, identifying on follow-up 646 recurrent colorectal adenoma cases and 1,104 control subjects who had a baseline colorectal adenoma, but no recurrence. We plan collaborations with the PLCO Colon Committee and other interested investigators for a coordinated analysis of selected risk factors for colorectal adenoma recurrence. Factors to be evaluated include smoking behavior, use of non-steroidal anti-inflammatory drugs (NSAIDs), body mass index (BMI), energy balance, physical activity, family history, and dietary intake of meat, meat mutagens, heme iron, fruits, vegetables, flavonoids, dietary sources of flavonoids, coffee, tea, caffeine, dairy products, calcium, fatty acids, and fiber. We will use unconditional logistic regression to obtain odds ratios (ORs) and 95% confidence intervals (CI). We will evaluate time to surveillance colonoscopy and number of surveillance colonoscopies as both potential confounders and stratification factors. Colorectal adenomas will also be further categorized into advanced and nonadvanced to evaluate if risk factors vary by clinically relevant adenoma characteristics. Because an active, broad and productive research program on colorectal tumors is underway in the PLCO Trial, there will be added-value opportunities to compare risk factor profiles for recurrent adenoma with the profiles for other colorectal tumor categories in the same study population. No other study of recurrent colorectal adenoma has had this capacity. A working group is formed among the lead investigators (see A.5. Investigator Team) to carry out all 11 proposed analyses in a coordinated fashion. A summary of the literature and the coordinated study design is provided from C.2. to C.5.; specifics for the fruits/vegetables, fiber and family history analyses are detailed in C.6-8.