BMI and colorectal adenomas in familial colorectal cancer

A. Botma1, M. Calligaro1, A.E. van der Meulen- de Jong2, H.F.A. Vasen2,3, E. Kampman2

Wageningen University, division of Human Nutrition1; Department of Gastroenterology, Leiden University Medical Center2; Netherlands Foundation for the Detection of Hereditary Tumours, Leiden3

For persons with one 1st degree family member diagnosed with colorectal cancer under 50 years of age or with two 1st degree family members diagnosed at any age, colorectal cancer risk is increased. This increased risk may be due to shared genes, shared environment or a combination of both. Overweight is positively associated with sporadic colorectal tumour development. In some studies this is most pronounced among those with at least one 1st degree family members diagnosed with CRC at any age.

Therefore, we examined the association between body mass index (BMI) and histological confirmed colorectal adenomas in 512 persons who participated in the Familial Colorectal Tumour Screening (FACTS)-study between 2003 and 2006. All participants underwent a colonoscopy and filled out a lifestyle and dietary questionnaire. In 82 participants (16 %) adenomas were found to be present, while 68 persons (13 %) had exclusively hyperplasic polyps. BMI was calculated using self reported weight and height. Prevalence ratios (PRs) were calculated using a modified Poisson regression approach adjusting for age, gender, energy intake and number of family members affected.

High BMI (≥27.0 kg/m2) was associated with a 1.2 times (95%CI 0.7-1.9) higher risk of colorectal adenomas as compared to those in the lowest tertile (BMI <23.7 kg/m2). Stratified analyses showed that PRs were increased in persons with the strongest family history: PR 1.8 (95%CI 0.9-3.7) highest versus lowest tertile. No associations were found between BMI and hyperplastic polyps. These results suggest a positive association between BMI and colorectal adenomas in persons with a strong family history. Even stronger associations were seen when the strength of the family history increased. In future we will also evaluate this association in an ongoing study among at least 440 individuals with the Lynch Syndrome.