From the Guidelines
Melatonin has shown no significant impact on anxiety in cancer survivors.
Findings on Anxiety
- A clinical trial of 128 participants with colorectal cancer found no impact on anxiety when 6 mg of melatonin was taken at bedtime compared to zolpidem for sleep during chemotherapy 1.
- Another RCT found no impact on anxiety with the use of perioperative melatonin for breast cancer in a small sample of 54 women 1.
- A trial among patients with lung cancer post resection also found no impact on anxiety in a small subset of participants, although anxiety was a relatively minor secondary outcome and not a presenting concern for the participants upon enrollment 1.
Findings on Depression
- A small RCT found a significant reduction in the number of women with depression according to the Major Depression Inventory in the perioperative period for women with breast cancer when melatonin was given at 6 mg once daily at night 1.
- However, other trials found no changes in depression when melatonin was taken at 6 mg once daily at night for 30 days in participants with colorectal cancer while receiving chemotherapy 1, or when 3 mg of melatonin was taken daily in a trial exploring melatonin for sleep, mood, and hot flashes 1.
Findings on Fatigue
- A small phase II crossover RCT found no significant differences in fatigue in patients with advanced cancer receiving 20 mg of melatonin once daily for 1 week compared to placebo 1.
Overall
The current evidence suggests that melatonin may have a limited role in managing symptoms such as anxiety, depression, and fatigue in cancer survivors, although more research is needed to fully understand its potential benefits and limitations.
From the Research
Melatonin and Cancer Treatment
The studies on melatonin, a hormone that regulates sleep-wake cycles, have shown promising results in cancer treatment. The key findings of these studies are:
- Melatonin has been found to mitigate cancer at the initiation, progression, and metastasis phases 2
- It has been shown to improve the sensitivity of cancers to inhibition by conventional drugs and render cancers previously resistant to treatment sensitive to these therapies 2, 3
- Melatonin has been found to inhibit molecular processes associated with metastasis, limiting the entrance of cancer cells into the vascular system and preventing them from establishing secondary growths at distant sites 2
Mechanisms of Melatonin's Anticancer Effects
The mechanisms of melatonin's anticancer effects are not fully understood, but studies suggest that it may:
- Act through membrane receptor-mediated and membrane receptor-independent pathways 2
- Have antioxidant, antiproliferative, immune-modulating, and hormone-modulating properties 4, 5
- Disrupt the circadian cycle, which may contribute to its anticancer effects 3, 5
Clinical Applications of Melatonin in Cancer Treatment
The clinical applications of melatonin in cancer treatment are being explored, with studies showing that it may:
- Improve survival and ameliorate the side effects of chemotherapy 4, 6
- Be used as an adjuvant therapy to improve the efficacy of conventional cancer treatments 4, 6
- Have potential as a preventive and therapeutic agent for cancer treatment, although further research is needed to fully understand its effects and to overcome the challenges of its clinical application 5
Benefits and Limitations of Melatonin in Cancer Treatment
The benefits of melatonin in cancer treatment include:
- Improved survival and reduced risk of death at 1 year 4, 6
- Amelioration of chemotherapy-associated toxicities, such as asthenia, leucopenia, nausea and vomiting, hypotension, and thrombocytopenia 4 The limitations of melatonin in cancer treatment include:
- The need for further research to fully understand its mechanisms of action and to overcome the challenges of its clinical application 5
- The potential for variability in response to melatonin treatment, depending on the type of cancer and individual patient characteristics 3, 5