Dtsch Arztebl Int
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The treatment options for patients with progressive malignant tumors despite primary radiotherapy are often limited. In selected cases, re-irradiation can be offered. This article concerns the selection criteria and results of re-irradiation for certain types of cancer. ⋯ Re-irradiation is a treatment option for selected cancer patients. As the available scientific evidence is limited, multidisciplinary collaboration and participatory decision-making are particularly important.
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Observational epidemiological studies often yield different results on the same research question. In this article, we explain how this comes about. ⋯ The above reasons why epidemiological study results can be heterogeneous are explained in this review. Quantitative bias analyses and sensitivity analyses with alternative data evaluation strategies can help explain divergent results on one and the same question.