Funding for this research was provided by:
St. Olavs Hospital Universitetssykehuset i Trondheim (35/15)
The Cancer Trust (Unknown)
Hole's Legacy (Unknown)
Norwegian Hospital Foundation (335007)
Received: 29 June 2020
Accepted: 26 September 2020
First Online: 9 October 2020
Ethical approval and consent to participate
: Both surveys included in this study were conducted according to Norwegian regulations for surveys. The Regional Committee for Medical and Health Research (REK) South East approved the 1996 and 2015 studies. Return of the questionnaire was regarded as informed consent.
: Not relevant.
: The authors declare that they have no competing interests.