Medical Statistics and Biomathematics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
Recent Results Cancer Res. 2021;218:15-29. doi: 10.1007/978-3-030-63749-1_2.
Cancer is the second leading cause of death globally. Malignant tumours are responsible for about 9.6 million deaths in 2018 (Ritchie H (2019) How many people in the world die from cancer? https://ourworldindata.org/how-many-people-in-the-world-die-from-cancer ). Worldwide, about 1 in 6 deaths is due to cancer. This confronts researches with the question of their origin and doctors with treatment options. It is common sense that great efforts should be done in order to reduce the number of cancer-specific deaths. In recent years, in lots of countries a variety of cancer screening programs have been developed, investigated and improved. The basic idea of this approach seems to be quite simple: Tumours will be detected at a very early stage when patients do not yet feel clinical symptoms. Thus, using an appropriate therapy, progression of the disease can be prevented and, concerning a whole population, disease-specific mortality should be reduced. Actually, after the introduction of screening programs, an increasing number of new cancer cases can be observed associated with an apparent reduction of the case fatality rate (i.e. the proportion of deaths due to cancer). Partly, the increasing number of cancers may be explained by the fact that people have a higher life expectancy. Under this aspect, the decreased case fatality rate could be considered as a success which may be attributed to screening efforts. However, there is still insufficient evidence affirming benefits of screening programs for crucial outcomes, i.e. all-cause mortality. In this narrative review, the phenomenon that probabilities and risks are rather often interpreted in an inadmissible way will be described. Furthermore, conceptual issues and inconsistencies between evidence and opinion about screening will be explored.
癌症是全球第二大死亡原因。恶性肿瘤导致 2018 年约 960 万人死亡（Ritchie H (2019) 全球有多少人死于癌症？https://ourworldindata.org/how-many-people-in-the-world-die-from-cancer ）。全世界约有 1/6 的死亡归因于癌症。这使研究人员面临其起源的问题，也使医生面临治疗选择的问题。常识是，应该做出巨大努力来减少癌症特异性死亡人数。近年来，许多国家都开发、研究和改进了各种癌症筛查计划。这种方法的基本思路似乎非常简单：当患者尚未出现临床症状时，肿瘤将在非常早期被检测到。因此，通过适当的治疗，可以防止疾病的进展，并且对于整个人群而言，可以降低特定疾病的死亡率。实际上，在引入筛查计划后，可以观察到越来越多的新癌症病例，同时明显降低了病例死亡率（即癌症导致的死亡比例）。部分原因是由于人们的预期寿命延长，导致癌症病例的增加。从这个角度来看，降低的病例死亡率可以被认为是成功的，这可能归因于筛查工作。然而，仍然没有足够的证据证实筛查计划对关键结果（即全因死亡率）有收益。在这篇叙述性综述中，将描述概率和风险经常被以不可接受的方式解释的现象。此外，还将探讨有关筛查的证据和意见之间的概念问题和不一致性。
