Since 2002, statutory health insurances in Germany have offered an endoscopic examination of the colon (colonoscopy) free of charge for all insured persons from the age of 55. Germany was the first country to make nationwide endoscopic screening for bowel cancer a part of its statutory early cancer detection program.
Scientists headed by Professor Hermann Brenner at DKFZ have now published a first calculation of the number of colorectal cancers prevented between 2003 and 2010 thanks to colonoscopy screening. The results will serve as a decision-making basis for an evidence-based evaluation of the program. Moreover, it is important for each participant to know about the benefits of the examination which is wrongly feared by many as being very unpleasant.
The researchers evaluated all 1.8 million colonoscopies which have been carried out to date in the screening program. As a calculation basis they used the number of discovered and removed advanced precancerous lesions (adenomas) which are highly likely to progress into cancer. The epidemiologists have estimated that participation in screening colonoscopy will prevent about 15,000 cases of colorectal cancer by the year 2010.
About 73.000 new cases of colorectal cancer are diagnosed each year in Germany. Around 40 percent of patients die within five years after diagnosis and another portion of sufferers succumb to the disease in the course of the following years. Therefore, Brenner's research team expects that the colonoscopy program will save around 7,500 lives between the years of 2003 and 2010 thanks to the removal of precancerous lesions alone. Moreover, since colonoscopy examinations detect cancer usually at an early stage when it is still curable, the screening program will prevent even more deaths.
The results obtained are based on complex calculations: The number of advanced adenomas found must calculated against the probability that these cancer precursors turn into cancer within a particular period of time. In addition, the calculation takes account of other factors such as the percentage of screening participants who die of other causes before cancer occurs and the participation rate in the respective age groups.
The investigators calculated the number of cancer cases prevented for each year individually and accumulated the values. Although the number of advanced adenomas discovered remains nearly constant over the years, the rate of cancer cases prevented rises each year, since many of the adenomas discovered and removed would otherwise have become cancerous several years later.
The yearly participation rate in colonoscopy screening has remained almost constant since 2003 at about four percent of eligible women and three percent of eligible men. Participants with inconspicuous examination results are offered a second examination free of charge after ten years. Thus, the total participation rate among those under 70, projected to the ten years between first and second screening colonoscopy, is 40 percent among women and 30 percent among men. "This is not bad for a beginning," says Hermann Brenner, "but if we succeeded in encouraging even more people to participate in the screening program – such as by sending personal invitations to examinations due – many more cancers could be prevented."
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