The Effect of Melatonin on Depression, Anxiety, Cognitive Function and Sleep Disturbances in Breast Cancer Patients

About 1.4 million women are diagnosed with breast cancer every year. Breast cancer is the most common malignancy among women worldwide constituting about 1/5 of all cancer types. Breast cancer diagnosis and treatment, and the months following primary therapy are stressful times for most women. Aside from the actual "cancer threat" many women experience various degrees of depression, anxiety, sleep disturbances and memory/concentration problems (cognitive dysfunction). Naturally these factors influence the quality of life but also contribute to morbidity and mortality. Melatonin is a regulatory circadian hormone having, among others, hypnotic, sedative, anxiolytic and possibly anti-depressive effects. It has very low toxicity and very few adverse effects. The purpose of this project is to test melatonin (6 mg daily for 1 week preoperatively to 12 weeks postoperatively) on breast cancer patients and hopefully hereby be able to prevent depression, anxiety, sleep disturbances and cognitive dysfunction. On an overall perspective this will hopefully contribute to improving the quality of life for these patients and extend their lifetime. Furthermore the investigators will be examining whether a specific gene called a clock-gene (HPER3) is correlated with an increased risk of depression, sleep disturbances or cognitive dysfunction. If this is the case it could become possible to identify women with an increased risk and provide prophylactic treatment for those with a risk of developing a depression, sleep disturbances or cognitive disturbances. Sample size calculations were based on our primary outcome parameter. Using a conservative estimate for the incidence of depression, the investigators expect to find a reduction from 30% to 15% with melatonin treatment. Sample size is sufficient to include our secondary and tertiary outcome parameters as well. The sample size calculations were calculated with a power of 80%, a type I error of 5% and a type II error of 20%.