Digital Public Defence: Tone Hovda Tone Hovda at Institute of Clinical Medicine will be defending the thesis "Improved breast cancer screening for women and society: A radiological approach" for the degree of PhD (Philosophiae Doctor). 

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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.

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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.

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Adjudication committee

  • First opponent: Principal Investigator Ritse Mann, Radboud University Medical Center, Nijmegen, the Netherlands
  • Second opponent: Professor Sylvia Heywang-Köbrunner, Referenzzentrum Mammographie München, Germany
  • Third member and chair of the evaluation committee: Associate Professor Tor Erik Rusten, Institute of Clinical Medicine, University of Oslo

Chair of defence

Professor Emeritus Torill Sauer, Institute of Clinical Medicine, University of Oslo

Principal Supervisor

Professor Solveig Hofvind, Oslo Metropolitan University


The overall aim of the PhD project was to investigate ways to improve early detection of breast cancers and included analyses of screening techniques and screen-readers’ performance. One study compared outcome of screening with digital breast tomosynthesis (DBT), a new “3D” mammography technique versus standard digital mammography, while the other study was a radiological review of mammograms from diagnosis and prior screening from women diagnosed with screen-detected and interval cancers.

In the first study, 34641, women residing in Oslo were screened with DBT while 57763, women from Vestfold or Vestre Viken were screened with standard 2D digital mammography, DM, during the period 2014-2015. A 50% increase in cancer detection was observed for those screened with DBT versus DM. No difference in rates of interval cancer was observed. Cancers detected with DBT were mainly smaller and less aggressive compared with those detected with DM. Thus, whether the increased cancer detection represents clinically significant cancers, remains debatable, and as of today, the knowledge base for implementation of screening with DBT in BreastScreen Norway is considered insufficient.

In the second study, panels of five radiologists performed nationwide retrospective reviews of mammograms from diagnosis and prior screening from 1225 women diagnosed with screen-detected cancer and 1010 women diagnosed with interval cancer in BreastScreen Norway. The reviews were consensus based and fully informed with all images available. In the majority of the reviewed cases, no abnormalities at all, or only minor, non-specific findings were retrospectively visible at the later cancer site. However, in about 20% of the reviewed cases, findings that were more obvious were observed on prior screening mammograms, with a potential for earlier diagnosis. Education, increased awareness and regular self-audits may increase screen-readers’ performance and reduce cancers missed at screening.

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Published Jan. 17, 2022 3:07 PM - Last modified Jan. 31, 2022 11:10 AM