Volume 68 - 2005 - Fasc.2 - Symposium
Report on the Belgian consensus meeting on Colorectal cancer screening
Screening and prevention of colorectal cancer must be a public health priority. It is the most frequent malignancy in Europe, the second leading cause of cancer death, including Belgium where more than 6.000 new cases occur per year. Various screening modalities, from non invasive to invasive are available and cur- rently in use and they are all cost-effective in comparison with no screening. The decision as to which screening test to use should be made by the patient and clinician. Consensus documents prepared by the Belgian scientific community appear in this issue of Acta Gastroenterologica Belgica, summarizing the scientific evidence in favour as well as the limitations of fecal occult blood tests, flexible sigmoidoscopy, videocolonoscopy and virtual colonoscopy. (Acta gastroenterol. belg., 2005, 68, 239-240).
Risk stratification for colorectal cancer and implications for screening
In addition to the well-recognized syndromes described (FAP, HNPCC) clusters of colorectal cancers occur in families much more often than would be expected by chance. This familial clus- tering in about 10-20% of colorectal cancers has implications for screening because the immediate family members of a patient with apparent sporadic colorectal cancer have a twofold to threefold increased risk of the disease. The magnitude of the risk depends on the age at diagnosis of the index case, the degree of kinship of the index case to the at-risk case, and the number of affected relatives. In addition to screening the easily identifiable high-risk groups such as FAP and HNPCC, care should be taken to recognize inter- mediate-risk patients and to provide them with appropriate screening recommendations. Because the molecular basis and the natural history of these intermediate-risk patients are largely unknown, screening recommendations are as yet more empirical. If a person has a first degree relative with colon cancer, average risk colon cancer screening is recommended, but starting at age 40 years. The decreased age is given because the risk at age 40 for those with an affected first-degree relative is similar to the risk at age 50 for the general population. An individual with two first- degree relatives affected with colon cancer or one first-degree rel- ative diagnosed under the age of 60 y should have colonoscopy beginning at age 40, or 10 years younger than the earliest case in the family. Colonoscopy should be repeated every five years if neg- ative. An even stronger family history of colon cancer syndromes of colon cancer.should suggest the consideration of one of the inherited syndromes.. (Acta gastroenterol. belg., 2005, 68, 241-242).
Faecal occult blood test as a screening test for colorectal cancer
Screening for colorectal cancer with faecal occult blood test (FOBT) has been shown in randomised controlled trials to decrease mortality from this disease. The time has come to imple- ment well-organised FOBT screening of the average-risk popula- tion. In order to have a high level of uptake, this program requires a substantial amount of initial planning and resource allocation, including defining roles of the different health professionals, training of the community of general practitioners together with proper education and information of the public on the risk factors for CRC and the alternative screening tools. The strengths and weaknesses of the available FOBT's are discussed and arguments are advanced to their use for screening in the average-risk population. (Acta gastroenterol. belg., 2005, 68, 244-246).
Flexible sigmoidoscopy as a screening test for colorectal cancer
Flexible sigmoidoscopy (FS) is one of the screening modalities for colorectal cancer. The rationale for screening with flexible sig- moidoscopy is that it provides direct visualisation of the colon, and suspicious lesions can be biopsied. The most obvious disadvantage is that it examines only the lower third of the colon. The technical aspects of FS are sufficiently clear to enable us to define what FS can and cannot do. From the point of view of screening, FS clear- ly cannot completely exclude the presence of colon cancer in all asymptomatic people. A distinction must be made between screen- ing the general population and testing the individual seeking screening. For the former, obtaining the greatest mortality benefit safely and at an acceptable cost to the nation is the crux of the mat- ter. Recently published data indicate that FS is a cost-effective screening strategy, although colonoscopy and annual fecal occult blood test avert a greater number of cancer deaths. The results of randomised controlled trials of screening FS and colonoscopy, cur- rently being conducted, will allow us to make a more accurate comparison with the established data regarding fecal occult blood test. In conclusion, flexible sigmoidoscopy every 5 years with or without FOBT is one of the screening methods recommended by major professional organizations. It identifies 50 to 70% of the advanced neoplasms, if any discovery of a distal neoplasia is fol- lowed up with a total examination of the colon by colonoscopy. (Acta gastroenterol. belg., 2005, 68, 248-249).
Colonoscopy as a screening test for colorectal cancer
Colonoscopy is the current gold standard for the diagnosis and treatment of colorectal neoplasms. Several gastroenterological and/or endoscopical societies recommend screening by colonoscopy in high risk patients for colorectal cancer whilst for average risk patients colonoscopy remains a valid option. In some countries screening colonoscopy is now covered by medical insur- ance. It is also the final common pathway of all colorectal cancer screening methods. This paper addresses the advantages and also limitations of colonoscopy as the first procedure for colorectal screening and emphasizes the importance of organized training and continuous assessment of competence of gastroenterologists and the necessity to have quality control audits of the endoscopy units. (Acta gastroenterol. belg., 2005, 68, 251-256).
Computed tomographic colonography
Computed tomographic colonography, also called virtual colonoscopy, is an evolving technology under evaluation as a new method of screening for colorectal cancer. However, its perfor- mance as a test has varied widely across studies, and the reasons for these discrepancies are poorly defined. We provide an overview of some potential causes and discuss the available, often indirect, evidence. In addition, several other obstacles that may influence implementation are discussed. Future investigations should demonstrate the influence of these potential factors on sensitivity of computed tomographic colonography. Despite a growing body of evidence, it remains uncertain to what extent patient accep- tance, radiation issues, flat lesions, and extracolonic findings will be a stumbling block to using computed tomographic colonogra- phy for colorectal cancer screening. (Acta gastroenterol. belg., 2005, 68, 258-260).