On March 24, Danielle Starreveld obtained her doctorate at Leiden University for her dissertation entitled: ‘Light therapy for cancer-related fatigue in (non-)Hodgkin lymphoma survivors’. Her supervisors were Prof. Dr. EMA Bleiker, Prof. Dr. Ir. FE van Leeuwen. Dr LA Daniels acted as co-supervisor. Danielle Starreveld is currently working as a postdoc researcher at Erasmus MC.
What was the aim of your PhD research?
Fatigue after cancer is common in survivors of Hodgkin’s lymphoma or diffuse large B-cell lymphoma. Treatments such as physical activity and cognitive behavioral therapy are effective in reducing this fatigue. The disadvantage of these treatments is that they require a lot of motivation from the patient and/or expensive professional guidance. For this reason, it remains interesting to investigate alternative treatments. Within the SPARKLE study, we looked at whether light therapy can be used as an effective treatment for persistent fatigue after the treatment of these cancers.
What would you like the hematologist to know about your examination?
We conducted a randomized study in which half of the participants were exposed to bright white light (the intervention) and the other half to dim white light (the control). Our participants had been treated on average 13 years ago and had suffered from chronic fatigue all the time. This has a major impact on their daily life. We expected that the intervention would lead to a reduction in this fatigue, but we were surprised to see that both participants in the intervention and control groups experienced a decrease in their fatigue. For a large proportion of the participants this decrease was clinically relevant. This decrease in the whole group is of course very important, but we need to further investigate which parts of our study protocol led to this positive result.
What was the most difficult part of your research?
The most difficult part of this research was, and is, the complexity of fatigue after cancer. We still don’t really know which factors ensure that patient A does develop fatigue after his diagnosis and treatment and patient B does not. The fact that we found no difference between the control and intervention groups may also be due to the fact that the biological clock is no longer disrupted in survivors with chronic fatigue after cancer. The positive results of light therapy are most likely due to light synchronizing the biological clock with the outside world. So if the biological clock is already synchronized, there is little room to restore it. Nevertheless, it is quite possible that the biological clock is disrupted by cancer treatment and that it influences the development of fatigue. If so, then light therapy during treatment may help reduce or prevent fatigue after cancer.
What moment/insight brought about a breakthrough?
We also conducted a questionnaire survey of survivors with and without fatigue to see if the sleep rhythms of fatigued survivors were different from those without fatigue. If the biological clock is disturbed and light therapy in the morning restores this, you expect that the sleep rhythm of people with fatigue is delayed. However, the results of our questionnaire study showed that there is no difference in the sleep rhythm of survivors with or without fatigue. We did see differences in sleep quality. This may therefore play a more important role in chronic fatigue in people who had been treated for a longer period of time before their diagnosis.
Which publication is a ‘must read’ for you?
The main chapter of my thesis is the article describing the most important outcomes of the SPARKLE study: ‘Light Therapy for Cancer-Related Fatigue in (Non-)Hodgkin Lymphoma Survivors: Results of a Randomized Controlled Trial’.