# Melatonin as a cancer adjunct

Source: https://onco.cc/technologies/melatonin-cancer/  
OnCo record `melatonin-cancer` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Melatonin helps some people sleep and is safe at usual doses, but the claim that high-dose melatonin improves survival rests on a series of small unblinded trials from one group that has never been reproduced elsewhere. It is not a cancer treatment.

## Summary

Melatonin, the pineal hormone that signals night, has antioxidant, immunomodulatory and antiproliferative effects in laboratory models. A 2012 meta-analysis of randomised trials of 20 mg melatonin alongside chemotherapy reported improved one-year survival and reduced toxicity, but almost all included trials came from a single Italian group, were unblinded and small, and independent trials have not replicated the survival effect. Better-conducted trials of melatonin for sleep, delirium and fatigue in cancer patients are mixed, with some benefit for sleep quality and little for fatigue. Low-dose melatonin is a reasonable short-term sleep aid in survivors when behavioural therapy is unavailable. High-dose melatonin as an anticancer adjunct is unproven; it may interact with sedatives and anticoagulants.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-09-10
- Tags: complementary; supportive-care; evidence:insufficient
- Principle: Melatonin acts on MT1 and MT2 receptors and as a free-radical scavenger, with circadian and putative oncostatic effects observed mainly in vitro and in rodents.
- Strengths: Safe and cheap; Plausible for sleep disturbance
- Limitations: Survival trials from a single unblinded source; No independent replication; Fatigue trials negative or mixed

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Melatonin
- Melatonin as adjuvant cancer care with and without chemotherapy: systematic review and meta-analysis (Integr Cancer Ther 2012): https://doi.org/10.1177/1534735411425484
- MSK About Herbs: Melatonin: https://www.mskcc.org/cancer-care/integrative-medicine/herbs/melatonin

## Connected records

- fronts: [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/), [Sleep and circadian interventions in cancer](https://onco.cc/technologies/sleep-circadian-interventions/)
- bottlenecks: [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/), [Preclinical results do not reproduce](https://onco.cc/bottlenecks/b-reproducibility/)
- key papers: [Melatonin as adjuvant cancer care with and without chemotherapy: a systematic review and meta-analysis of randomized trials](https://onco.cc/key-papers/paper-seely-integr-cancer-ther/)

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