Received: 16 September 2021
Accepted: 7 March 2022
First Online: 21 March 2022
: The project was performed in accordance with the Declaration of Helsinki. The Regional Committee for Medical and Health Research Ethics (REC) in Norway approved the study (2016/2172/REK midt). Written informed consent was waived due to the retrospective observational nature of the study. All treatment was given according to local guidelines from 1980–1992, and according to similar, national guidelines from 1993–2016.
: Not applicable.
: The authors declare no competing interests.