Funding for this research was provided by:
German Cancer Aid (111232)
Deutsche Forschungsgemeinschaft (Open Access Publishing)
Received: 16 April 2019
Accepted: 19 August 2019
First Online: 2 September 2019
Ethics approval and consent to participate
: Individual consent for this study was waivered because exclusively routinely collected and pseudonymised data was used to conduct secondary data analyses. The project has been approved by the institutional review board of the Medical Faculty of Heidelberg University, Germany (ref. S-319/2013) and by the institutional review board of the Tomsk Regional Oncological Hospital, Russia (reg. no. 60/2019). We declare that research has been conducted in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Not applicable
: The authors declare that they have no competing interests.