Erik Fernström: Biological effects in the brain after radiotherapy can be measured in body fluids Erik Fernström’s thesis explores the balance
Erik Fernström’s thesis explores the balance between effective cancer treatment and the risk of long-term side effects affecting healthy brain tissue. A better understanding of what causes these side effects could make it easier to provide patients with the right care and support.
ERIK FERNSTRÖM
Dissertation defense: 2 October 2026 (click for details)
Doctoral thesis: The brain in the beam path – outcomes and biomarkers in clinical radiotherapy
Research area: Oncology
Sahlgrenska Academy, The Institute of Clinical Sciences
Radiotherapy is an important part of both curative cancer treatment and treatment aimed at relieving symptoms. At the same time, nearby healthy tissue may also be exposed to radiation, potentially causing side effects that can persist for a long time.
As more people are cured of cancer and live for many years after treatment, understanding and reducing long-term side effects is becoming increasingly important. Radiation targeting tumors in the brain or head and neck region can, for example, cause long-term problems affecting the eyes, as well as severe fatigue and difficulties with concentration or memory.
“There are, of course, many factors that can contribute to fatigue, low mood or memory problems in patients with cancer, and it can be difficult to determine whether radiation exposure to the brain is one of them,” says Erik Fernström, oncologist at Sahlgrenska University Hospital and doctoral student at the Institute of Clinical Sciences.
Reducing local damage and measuring biological effects
The thesis follows two lines of research: how to reduce local tissue damage during radiotherapy for tumors of the nose and sinuses, and how to measure biological effects in the brain after radiotherapy.
“We measured how the levels of different proteins released from the brain change in cerebrospinal fluid and blood after radiotherapy involving the brain. We then investigated whether these biological changes reflect the radiation dose as well as patients’ memory function and quality of life.”
Tracking the protein NfL may provide an important clue
The findings show that biological effects in the brain after radiotherapy can be measured in body fluids, and that the protein neurofilament light (NfL), which can be detected in both blood and cerebrospinal fluid, is a particularly promising marker. NfL is found mainly in the long projections of nerve cells and can be released when nerve cells are affected or damaged.
“We also found a strong association between NfL levels in blood and cerebrospinal fluid. This suggests that NfL levels in the blood could potentially be used to monitor effects on nerve tissue after radiotherapy.”
NfL levels were also associated with quality of life and depressive symptoms during follow-up. The findings suggest that the radiation dose received by healthy brain tissue during treatment for head and neck cancer may play a role in both side effects and biological processes in the brain. A better understanding of the causes of these side effects could make it easier to provide patients with appropriate care and support.
“These methods could potentially be used to evaluate the side effects of new treatment techniques for tumors located close to the brain. However, the studies are small, and the findings need to be confirmed in larger groups of patients before blood tests like these can be used to assess the risk of side effects in individual patients.”
What has been the most rewarding and challenging part of your doctoral project?
“The most rewarding part has been the opportunity to delve deeper into and learn more about the effects of the treatments I work with every day – knowledge that is directly useful in my daily work with patients. One challenge is that the research has to fit in with the patients’ regular treatment while also being carried out alongside my own clinical work.”
Text: Susanne Lj Westergren