Funding for this research was provided by:
Fundação para a Ciência e a Tecnologia (SFRH/BD/102181/2014, SFRH/BD/92630/2013)
Text and Data Mining valid from 2017-06-16
Received: 11 April 2016
Accepted: 31 May 2017
First Online: 16 June 2017
Compliance with ethical standards
: FF and ARC have received co-funded by the “Fundação para a Ciência e a Tecnologia” and the POPH/FSE Program (grant numbers SFRH/BD/92630/2013 and SFRH/BD/102181/2014, respectively). Data management activities were supported by the Chair on Pain Medicine of the Faculty of Medicine, University of Porto and by the Grünenthal Foundation – Portugal.
: The authors declare that they have no conflicts of interest.
: The study was approved by the Ethics Committee of the Portuguese Institute of Oncology of Porto (Ref. CES 406/011) and by the Portuguese Data Protection Authority (Ref. 9469/2012). All participants provided written informed consent.