Digital Public Defence: Kaitlyn Michiko Tsuruda

MSc Kaitlyn Michiko Tsuruda at Institute of Basic Medical Sciences will be defending the thesis “Overdiagnosis and 'underdiagnosis' in BreastScreen Norway” for the degree of PhD (Philosophiae Doctor).

Image may contain: Glasses, Forehead, Nose, Glasses, Cheek.

Photo: Elisabeth Jakobsen, Kreftregisteret.

The public defence will be held as a video conference over Zoom.

The defence will follow regular procedure as far as possible, hence it will be open to the public and the audience can ask ex auditorio questions when invited to do so.

Click here to participate in the public defence

Download Zoom here

Due to copyright reasons, an electronic copy of the thesis must be ordered from the faculty. In order for the faculty to have time to process the order, it must be received by the faculty no later than 2 days prior to the public defence. Orders received later than 2 days before the defence will not be processed. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

Digital Trial Lecture – time and place

See Digital Trial Lecture.

Adjudication committee

  • First opponent: Associate Professor Håkan Jonsson, Department of Epidemiology and Global Health, Umeå University, Sweden
  • Second opponent: Coordinator of Epidemiology and Evaluation group, PhD Maria Sala Serra, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Spain
  • Third member and chair of the evaluation committee: Professor II Mona Kristiansen Beyer, University of Oslo

Chair of the Defence

Professor Therese Sørlie, Faculty of Medicine, University of Oslo

Principal Supervisor

 Solveig Hofvind, Cancer Registry of Norway


One in eleven women in Norway will be diagnosed with breast cancer by age 75. Organized mammographic screening can detect early stage breast cancer and reduce deaths from this disease. However, screening involves harms, such as the potential detection of a slow growing breast cancer that would never present symptomatically during a woman’s lifetime (overdiagnosis). “Underdiagnosis” can also occur, which was defined as “failing” to diagnose a breast cancer that would present symptomatically during a woman’s lifetime. This thesis aimed to generate knowledge about these harms through three studies.

The first study demonstrated that radiologists and pathologists preferentially round tumour diameter measurements, which can lead to understaging but not overstaging.

The second study considered whether women with “missed” cancers that were diagnosed at a subsequent screening examination could be underdiagnosed. Based on their tumour characteristics and survival profile, it was posited that these women received a timely diagnosis.

The last study indicated that women have relatively less knowledge about overdiagnosis than other topics related to mammographic screening. This study highlights some of the challenges related to communicating information about overdiagnosis and screening.

Additional information

Contact the research support staff.

Published Sep. 10, 2021 1:06 PM - Last modified Sep. 23, 2021 9:24 AM