Aðalbygging
- Free admission
On Wednesday, 11 November 2026, Snædís Ragnarsdóttir will defend her doctoral thesis in biomedical sciences at the Faculty of Medicine, University of Iceland. The thesis is entitled: Aggressive ER-Positive Breast Cancer: Clinical and Biological Insights from TP53 Mutations, BRCA2 Deficiency and Early-Onset Disease.
The opponents are Dr Therese Sørlie, Professor at the University of Oslo, and Dr Sævar Ingþórsson, Associate Professor at the University of Iceland.
Stefán Þ. Sigurðsson, Professor, was the principal supervisor, Þorkell Guðjónsson, Lecturer, was the supervisor, and Linda Viðarsdóttir, Lecturer, was the co-supervisor. In addition, Bylgja Hilmarsdóttir, Lecturer, served on the doctoral committee.
Þórarinn Guðjónsson, Professor, will chair the ceremony, which will take place in the University of Iceland Ceremonial Hall and begin at 13:00.
Abstract
Estrogen receptor-positive (ER-positive) breast cancer generally has a favorable prognosis and responds to endocrine therapy. However, outcomes vary, and some subgroups display aggressive features.
This thesis used clinical, experimental and transcriptomic approaches to examine factors associated with adverse outcomes in breast cancer, with emphasis on ER-positive disease.
In an Icelandic cohort, the association between TP53 mutations and survival was evaluated, including analyses stratified by ER status. TP53 mutations were associated with poorer survival in ER-positive disease; exploratory analyses suggested that this association was particularly pronounced in Luminal A tumors.
Experimental studies showed that estradiol increased DNA damage and chromosomal instability in BRCA2-deficient ER-positive breast cancer cells, suggesting that BRCA2 deficiency may make these cells more susceptible to genomic stress associated with estrogen exposure.
Transcriptomic analyses showed that BRCA2-mutated tumors and ER-positive BRCA2 wild-type tumors from younger patients had partially overlapping activity patterns in pathways related to proliferation, cell-cycle progression and growth-factor signaling. Despite these similarities, higher homologous recombination deficiency (HRD) scores were observed only in BRCA2-mutated tumors. The results provide insight into biologically aggressive subgroups of ER-positive breast cancer and improve our understanding of the clinical and molecular factors associated with adverse outcomes.
About the Doctoral Candidate
Snædís Ragnarsdóttir was born in Reykjavík in 1989. She completed the natural sciences programme at Kvennaskólinn in Reykjavík in 2009, earned a bachelor's degree in biomedical science from the University of Iceland in 2016, and a master's degree in biomedical science from the same university in 2019. She began her doctoral studies at the University of Iceland in the autumn of 2019.
Alongside her doctoral studies, Snædís has been involved in teaching practical classes in biochemistry, molecular life sciences and genetics, as well as training bachelor's and master's students at the University of Iceland.
Snædís's parents are Ragnar Karlsson and Karen Rögnvaldsdóttir. Her fiancé is Viktor Kristmannsson, and together they have two children, Viktoría Stella Viktorsdóttir and Andri Hrafn Viktorsson.
About events held at the University of Iceland
The content of events organised within the University of Iceland is the responsibility of the organisers, speakers, and other participants. The views, opinions, and statements expressed at such events, whether orally or in writing, are those of the individuals concerned and do not necessarily reflect the views, policies, or positions of the University of Iceland.
Share
Buses 14, 1, 6, 3 and 12 stop at the University of Iceland in Vatnsmýri. Buses 11 and 15 also stop nearby. Let's travel in an ecological way!