Falling Mortality Thanks to Improved Treatment for Colorectal Cancer

Even though it seems obvious to explain the trend towards fewer diagnoses of colorectal cancer with the introduction of screening colonoscopy as a GVK [German National Association of Statutory Health Insurance Funds] service in 2002, the scientific confirmation on the basis of representative epidemiological data constitutes an important step in the sense of evidence based medicine (1). The question that is more difficult to answer is: which role does (screening) colonoscopy have in the reduction of tumor-related mortality? Early detection of preliminary tumor stages and the associated fall in tumor incidence inevitably lead to an absolute reduction in tumor-associated deaths. The authors reporting the study, however, regard the redistribution to lower tumor stages also as a cause for the relative reduction in mortality they observed, and in their discussion section they express the vague suspicion that “advances in CRC treatment” may also have contributed to the decline in CRC mortality. In the past two decades, chemotherapy (2) and radiochemotherapy (3) have undergone significant improvements, but minimally invasive tumor resection has also improved—for example, as a result of laparoscopic surgical techniques (4). On the basis of an at best marginal stage shift between 2002 and 2018 (UICC I: from 17% to 19%, II: from 26% to 26%, III: from 27% to 28%, IV: from 30% to 27%) one can assume that the observed fall in mortality of –35.8% in men and as much as –40.5% in women is mostly the result of these therapeutic advances and to a lesser degree of the introduction of screening colonoscopy. Because of the lack of documented factors, epidemiological cancer registry data, such as the reported study is based on, are only to a limited degree suitable for uncovering the totality of associations between the pure data. This underlines once again that clinical cancer registry data should be used.