Funding for this research was provided by:
North Rhine-Westfalia Association for the Fight against Cancer, Germany
Text and Data Mining valid from 2018-07-20
Received: 9 March 2017
Accepted: 20 June 2018
First Online: 20 July 2018
Ethics approval and consent to participate
: Ethical committee approval was granted by the General Medical Council of Hamburg, Germany (reference number PV3547, 08 October 2010). The study has been approved by the department of data security of the German Pension Insurance Agency, Berlin, Germany. All study participants provided written informed consent for study participation, data analysis and publication.
: Not applicable.
: The authors declare that they have no competing interests.
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