Adverse effects of colorectal cancer screening with fecal occult blood test: a population-based organized program



J Lacroute, I Gendre, JM Boyaval, P Perrin, B Denis

Adverse effects (AE) of colorectal cancer (CRC) screening have not yet been assessed as thoroughly as those of mammography screening. Aim: to assess 1) AE of a CRC screening program with guaiac-based fecal occult blood test (gFOBT) and 2) the optimal method for their routine detection.

Methods        

Identification of AE of the organized CRC screening program with biennial gFOBT in progress in the Haut-Rhin since 2003 through 1) voluntary reporting by gastroenterologists, 2) AE report forms by general practitioners (GPs), 3) retrospective questionnaire mailed to GPs and 4) retrospective questionnaire mailed to persons explored by colonoscopy.

Results        

114,137 persons completed 173,352 gFOBTs in 4 years. 2194 of 3810 colonoscopic procedures displayed no neoplasia that is a 57.6% false positive rate. Overall, 17 (4.5/1000) serious AE were recorded: 4 (1.0/1000) perforations, 8 (2.1/1000) bleeding, 3 postpolypectomy syndromes and 2 major anxiety attacks. They resulted in 15 hospitalizations, 6 colonoscopic procedures, 5 surgical operations and 3 blood transfusions. 10 (58.8%) were voluntarily reported by gastroenterologists, 8 (47.1%) were notified by GPs answering the questionnaire and 1 through the AE report form and 7 (41.2%) by patients via the questionnaire. 4 undue surgical operations were recorded, 1 due to an erroneous CT diagnosis of CRC and 3 to an erroneous pathologic overdiagnosis of T1 malignant polyp. 50 colonoscopic procedures were repeated within 6 months without justification. 2288 (61.6%) persons explored by colonoscopy answered the questionnaire and reported 252 (11.1%) minor AE such as abdominal pain after the procedure (50 cases), change in bowel habits (59 cases), bloating (62 cases), nausea/vomiting (16 cases) and fever (11 cases). 494 (21.6%) reported stress when receiving the mail announcing the positive result, 397 (17.4%) judged the bowel preparation awful and 86 (3.8%) experienced pain during colonoscopy. 16 complained about the waiting period before the colonoscopy appointment. 305 GPs (51.4%) answered the questionnaire concerning 1877 patients and notified 80 AE (4.3%). Only 6 AE were reported with the AE report forms.

Conclusion        

Provided they are actively sought, AE of CRC screening with gFOBT are more frequent than previously reported. Though most of them are minor, the invited population should be informed. The detection of AE must rely on several sources of information. Voluntary reporting by gastroenterologists detects only the half of serious AE. The patient's questionnaire is the most sensitive method for the detection of minor AE and should be routinely proposed to persons screened by colonoscopy.



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