Reducing Cancer Side-effects With Systematic Light Exposure

Two independent but similar RCTs with a total of 144 breast cancer patients (Group 1 = 72 high risk patients; Group 2 = 72 low risk breast cancer patients) post-treatment screened for fatigue will be randomized to BWL (36 in each of the two groups) or dim light(DL) (36 in each of the two groups) exposure for 30 minutes/morning for 4 weeks, and assessed before, during, immediately and 3 months after the intervention. Measures include questionnaires, cognitive assessment, actigraphy, blood samples, saliva samples, and magnetic resonance imaging (MRI).

1.1 Aims and hypotheses. Aim 1: To test the efficacy of BWL on fatigue (primary outcome) in breast cancer patients.

Hypothesis 1: Compared with control participants exposed to DL, participants randomized to BWL will report less fatigue immediately and 3 months after the intervention.

Aim 2: To test the efficacy of BWL on cognitive functioning (secondary outcome).

Hypothesis 2: Compared with controls, BWL recipients will show improved cognitive functioning immediately and 3 months after the intervention.

Aim 3: To explore the effects of BWL on chronobiological, biological, and neurophysiological markers.

Hypothesis 3: BWL will be associated with normalized circadian activity rhythms (3a); improved sleep (3b); decreased inflammation (3c); increased cortical and subcortical grey matter density (3d); and increased cortical and subcortical white matter integrity (3e). If hypotheses 1 and/or 2 are confirmed, the mediating effects of the markers will be explored.

Inclusion criteria

- Group 1:

• High-risk breast cancer patients as defined by the Danish Breast Cancer Cooperative Group (DBCG) having received treatment according to the DBCG guidelines
• Minimum age of 18 years; completion of adjuvant whole breast radiation treatments
• A score <34 on the FACIT-Fatigue scale (see below) after radiotherapy
• Availability for home-based 4-week BWL/DL-treatment.

Exclusion criteria

• History of chronic fatigue disorders
• Pregnancy
• Confounding underlying medical illnesses such as significant pre-existing anemia
• Diagnosed or suspected psychiatric or medical condition that might contribute to fatigue (other than those caused by the cancer or its treatment)
• History of bipolar disease or mania (which are contra-indications for light treatment)
• Current clinical depression
• History of seasonal affective disorder
• Previous diagnosis of sleep apnea, restless legs or other sleep disorders (not including insomnia) known to affect fatigue
• Employment in shift work
• Chronic use of oral steroid medication
• Prior use of light treatment
• Use of photosensitising medications
• Plans to travel across meridians
• Insufficient Danish language proficiency

Inclusion criteria

- Group 2:

• Low-risk postmenopausal patients as defined by the DBCG having received breast-conserving surgery for lymph node-negative breast cancer
• Completion of adjuvant whole breast radiation treatments
• A score <34 on the FACIT Fatigue scale (see below) after radiotherapy
• Availability for home-based 4-week BWL/DL-treatment.

Exclusion criteria

• History of chronic fatigue disorders
• Pregnancy
• Confounding underlying medical illnesses such as significant pre-existing anemia
• Diagnosed or suspected psychiatric or medical condition that might contribute to fatigue (other than those caused by the cancer or its treatment)
• History of bipolar disease or mania (which are contra-indications for light treatment)
• Current clinical depression
• History of seasonal affective disorder
• Previous diagnosis of sleep apnea, restless legs or other sleep disorders (not including insomnia) known to affect fatigue
• Employment in shift work
• Chronic use of oral steroid medication
• Prior use of light treatment
• Use of photosensitising medications
• Plans to travel across meridians
• Insufficient Danish language proficiency