Prevalence of adenomas in familial colorectal cancer

A.E. van der Meulen-de Jong1, H. Wolters3, A.M.C. Witte3, J. Vecht3, W.R. ten Hove3, J.M.J.L Salemans3, F.M. Nagengast3, J.H. Kleibeuker3, G.F. Nelis 3, H.F.A. Vasen1,2
Department of Gastroenterology, Leiden University Medical Center1; The Netherlands Foundation for the Detection of Hereditary Tumours, Leiden2.; Member Collaborative Group FACT Study3

Subjects with one or two first degree relatives (FDR) with colorectal cancer (CRC) have a moderate risk for developing CRC (relative risk 4-6). The Familial Colorectal Cancer Study (FACTS) was started in The Netherlands in 2002. It is a national randomized clinical trial to evaluate the optimal surveillance interval (3 versus 6 years) for subjects (age 45-65 years old) with one first degree relative with CRC diagnosed below the age of 50 years (Group A) or two first degree relatives with CRC diagnosed at any age (Group B).

The study group is presented and the yield of first colonoscopy (t=0) is compared with the first life-time colonoscopy in a group of subjects (age > 40 years) comprising individuals  from Lynch Syndrome and FAP families who were found not to carry the mutation identified in the family1.

A total of 551 subjects (242 male) met the selection criteria. Ninety-five subjects did have an earlier colonoscopy and were excluded from this study. Group A included 224 subjects and group B included 232 subjects. Sixty-nine percent of all CRCs diagnosed in the FDRs was confirmed by pathology reports. The control group included 142 subjects aged > 40 years.

Adenomas were detected in 85 (18.6%) FACTS individuals and in 15 (10.6%) control subjects (P =  0.02). High risk adenomas occurred in 15 FACTS subjects (3.6%) and in 7 control individuals (4.9%)(NS). Two CRC were observed in the control group, and one CRC and one carcinoid in the FACTS group. Multiple adenomas were more often detected in the FACTS individuals (30/456; 6.6% vs. 3/142; 2.1%), P = 0.06. No difference in detection of adenomas was observed between FACTS group A and B (15.2% vs. 22.0%, P = 0.06).

The prevalence of adenomas and of multiple adenomas in subjects with familial colorectal cancer (FCC) were significant higher compared to the general population. Individuals with and without FCC are at equal risk of high risk adenomas during first life time colonoscopy. The FACTS will reveal the best surveillance interval for FCC.

1de Jong AE et al. Am J Gastroenterol. 2005;100(1):139-43