Effectiveness and efficiency of CT-colonography compared to conventional colonoscopy for the early detection and diagnosis of colorectal cancer

HEALTH POLITICAL BACKGROUND: Colorectal cancer (CC) is the second most common cancer and cause of cancer death for both men and women in Germany. Various methods for early detection of CC exist, including conventional coloscopy which is reimbursed within the scope of cancer screening, as well as computertomography-coloscopy (CTC) which is currently not reimbursed. SCIENTIFIC BACKGROUND: CTC is a mere diagnostic procedure which has a lower risk of perforation than conventional coloscopy. However, as it is an x-ray procedure, it exposes the patient to radiation. Conventional coloscopy is considered the gold standard due to its high sensitivity and specificity for locating adenomas. Furthermore, it offers the advantage that in addition to extended diagnostic measures therapeutic measures can be undertaken during the procedure. RESEARCH QUESTIONS: This HTA-report aims to evaluate the effectiveness and efficiency of CTC in comparison to conventional coloscopy in the early detection and diagnosis of colorectal cancer and/or its precursors and which ethical and legal aspects have to be considered. METHODS: The systematic literature search (27 international literature data bases) yielded a total of 1,713 abstracts. After a two-step selection process 36 publications remained to be assessed. RESULTS: The results regarding the effectivity of CTC in diagnosis and screening for colorectal cancer and/or its precursors are partly promising, however, they are very heterogeneous. Therefore, regarding its sensitivity and specificity, CTC cannot be considered an equivalent alternative to conventional coloscopy for diagnosis and screening. The heterogeneity of results is due to technical (device type, settings), patient dependent (preparation) and operator dependent (training) factors. No economic results for a comparison of the procedures for diagnosis exist. Regarding the cost-effectiveness of a CTC-screening, international model calculations are available. According to this calculation, the CTC-screening is cost-effective compared to the option ‘no screening’; however, conventional coloscopy-screening is generally more cost-effective. DISCUSSION: If modern CTC-devices are used with adequate technical settings, software, appropriate patient preparation and training of the operator, better results regarding sensitivity can be expected. Basically, the fact that no therapeutic measures (polypectomy) can be taken during CTC compared to conventional coloscopy needs to be considered. Unanswered medical questions pertain to the interval of examinations for screening (considering the radiation exposure), the approach to small polyps and the significance of flat and depressed lesions. Regarding its cost-effectiveness, conventional coloscopy-screening results in greater health benefits and lower costs than CTC-screening in most model calculations. These results cannot be applied to Germany directly. An important ethical aspect is the consideration of patient preferences regarding the procedures. Legal aspects concern the stipulation and maintenance of quality standards. CONCLUSIONS: At this time, a clear endorsement of CTC as an alternative procedure for diagnosis and screening to the current gold standard conventional coloscopy cannot be given. On the basis of the available literature this holds true for both the medical as well as the economic assessment. However, despite the numerous studies and analyses on this topic, this assessment is afflicted with uncertainties. Due to the rapid development of CTC, short term revisions of these research questions are needed.