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BJC Open article

British Journal of Cancer (2004) 90, 941–943. doi:10.1038/sj.bjc.6601626 www.bjcancer.com
Published online 2 March 2004

Melatonin and cancer risk: does light at night compromise physiologic cancer protection by lowering serum melatonin levels?

E S Schernhammer1,2 and K Schulmeister3

  1. 1Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
  2. 2Ludwig Boltzmann-Institute for Applied Cancer Research, KFJ-Spital, Vienna, Austria
  3. 3ARC Seibersdorf research, Health Physics Division, Seibersdorf A-2444, Austria

Correspondence: Dr ES Schernhammer, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. E-mail: eva.schernhammer@channing.harvard.edu

Received 9 October 2003; Revised 3 December 2003; Accepted 5 December 2003

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Abstract

The suprachiasmatic nuclei in the hypothalamus, one of the most important physiological determinants of alertness and performance, drive a circadian pacemaker in mammals, with an intrinsic period averaging 24h. Light is the primary stimulus to the disruption and resetting of this pacemaker, which is expressed in changing melatonin rhythms. Melatonin production in humans decreases when people are exposed to light at night. Since melatonin shows potential oncostatic action in a variety of tumours, it is possible that lowered serum melatonin levels caused by exposure to light at night enhance the general tumour development. Cancer is the second leading cause of death in industrialised countries like the United States, where a significant proportion of workers engage in shift work, making a hypothesised relation between light exposure at night and cancer risk relevant. Observational studies support an association between night work and cancer risk. We hypothesise that the potential primary culprit for this observed association is the lack of melatonin, a cancer-protective agent whose production is severely diminished in people exposed to light at night.

Keywords:

melatonin; cancer; light exposure; night work

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