Screening for Sporadic Colorectal Cancer

In a recent edition of Endoscopy, Lambert et al. provided a comprehensive overview of “Early Diagnosis and Prevention of Sporadic Colorectal Cancer” [1]. There are, however, errors, inaccuracies, and omissions in the review on which we feel obliged to comment. Under the subheading “Severe Complications of Screening,” a reference is made to “a small study of flexible sigmoidoscopy screening in Oslo” [2]. This study was not in Oslo. It was conducted in Telemark (a county in southern Norway), which is why it was called the “Telemark Polyp Study No. 1.” Admittedly this is no big deal, but it is surprising that reference is made to [2] and not to another paper from the same study [3], which refutes the suggestion that procedural complications might have been the cause of the observed increased mortality, and presents data suggesting more likely causes [3]. This is all the more surprising, since some of the co-authors of the review are very well acquainted with the study and with both of these Telemark Polyp Study publications [2] [3].

Under the subheading “Impact of Screening on Mortality and Incidence: Rigid and Flexible Sigmoidoscopy,” it is stated that “following rigid sigmoidoscopy a consistent 60 - 80 % decrease in the incidence of distal bowel cancer has been observed (Table 3)”. The reference to Table 3 implies that Thiis-Evensen et al. [2] is a study using rigid sigmoidoscopy - which it was not, as flexible endoscopy was used. Also, the design was a prospective, randomized study (not a case-control study, as stated in the table). Similarly, the study by Muller and Sonnenberg [4] referred to in the same table used flexible endoscopy, not rigid sigmoidoscopy.

Furthermore, under the same subtitle, there is reference to only three flexible sigmoidoscopy screening trials in progress - in the USA, UK [5] and Italy [6], respectively, the first testing the efficacy of flexible sigmoidoscopy repeated at 5-year intervals, the two latter ones evaluating a single flexible sigmoidoscopy screen. Again, it is surprising that no mention is made of the ongoing once-only flexible sigmoidoscopy screening study in Norway, with 21 000 individuals included in the screening arm [7], as this study is well known to some of the authors. To our knowledge, this is also the only study combining a randomized controlled design and a design intended to meet the requirements of a management study mimicking a national screening program.

References

• 1 Lambert R, Provenzale D, Ectors N. et al . Early diagnosis and prevention of sporadic colorectal cancer.  Endoscopy. 2001;  33 1042-1064
• 2 Thiis-Evensen E, Hoff G, Sauar J. et al . Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I.  Scand J Gastroenterol. 1999;  34 414-420
• 3 Hoff G, Thiis-Evensen E, Grotmol T. et al . Do undesirable effects of screening affect all cause mortality in flexible sigmoidoscopy programs? Experience from the Telemark Polyp Study 1983-96.  Eur J Cancer Prev. 2001;  10 131-137
• 4 Muller A D, Sonnenberg A. Prevention of colorectal cancer by flexible endoscopy and polypectomy: a case-control study of 32702 veterans.  Ann Intern Med. 1995;  123 904-910
• 5 Atkin W, Edwards R, Wardle J. et al . Investigators MF-ST. UK randomized trial of “once only” flexible sigmoidoscopy screening: baseline results.  Endoscopy. 1999;  31 (Suppl 1) E1
• 6 Senore C, Segnan N, Rossini F. et al . Screening for colorectal cancer by once-only sigmoidoscopy: a feasibility study in Turin, Italy.  J Med Screen. 1996;  3 72-78
• 7 Hoff G, Grotmol T, Bretthauer M. et al . Flexible sigmoidoscopy screening: a randomized, controlled study of the population in the south of Norway: the Norwegian Colorectal Cancer Prevention study (NORCCAP) [abstract].  Gastroenterology. 2001;  120 (Suppl 1) A 1195