This article has been retracted at the request of the authors. An honest error occurred while exporting data from the original EORTC dataset which was stored as SAS and then transformed into Excel and from Excel into SPSS, significantly affecting the results and conclusions. A revised manuscript, reporting the correct data, will be submitted to the journal where it will be subject to conventional peer review. We would like to apologize to the scientific community, the editors, and the reviewers for this mistake. Ivan Caramanna, Martin Klein, Martin van den Bent, Ahmed Idbaih, Wolfgang Wick, Martin J. B. Taphoorn, Linda Dirven and Jaap C. Reijneveld agree to this retraction. Andrew Bottomley did not respond to correspondence from the Editor about this retraction.
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