Further Potentially Carcinogenic Effects of Chronodisruption
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In addition to the suppression of melatonin production and circadian disruption with deregulation of peripheral growth control functions as discussed in the article, we would like to mention further pathophysiological mechanisms that are fundamental to chronodisruption and may therefore promote the development of cancer (1).
- Sleep disruption as a consequence of shift work can result in disruption of the hypothalamic-pituitary gland axis, which in turn triggers an increased release of glucocorticoids. A resulting chronic suppression of immune response after years of exposure may increase the susceptibility to developing cancer.
- In addition to changes to activity periods and dietary habits, night work can cause further lifestyle changes, for example with regard to alcohol and tobacco consumption, and may thus indirectly affect the pathogenesis of cancer.
- Even though the evidence is inconclusive regarding the cancer-protective effects of vitamin D (2), night work may result in lower exposure to UV light and therefore reduced production of vitamin D, which, for example, may facilitate the development of colorectal cancer.
How molecular-biological mechanisms in nocturnal exposure to light and chronodisruption influence the risk of disease is an important research field in occupational epidemiology. In the future it will be importance to study which shift roster triggers relevant chronodisruption. The increasing use of longitudinal study designs with prospective assessment of shift-work systems-as it would be possible for example in the context of the national cohort-can make a valuable contribution to this important research field.
PD Dr. med. Thomas Behrens, MPH
Dr. med. Birte Mester, MPH
Sabrina Hense, M.A. Soz.
Prof. Dr. rer. nat. Wolfgang Ahrens
Bremer Institut für Präventionsforschung und Sozialmedizin
28359 Bremen, Germany
|1.||Fritschi L: Shift work and cancer. BMJ 2009; 339: 2653. MEDLINE|
|2.||Zeeb H, Greinert R: The role of Vitamin D in cancer prevention—does UV protection conflict with the need to raise low levels of Vitamin D? Dtsch Arztebl Int 2010; 107(37): 638–43. VOLLTEXT|
|3.||Erren TC, Falaturi P, Morfeld P, Knauth P, Reiter R, Piekarski C: Shift work and cancer—the evidence and the challenge. Dtsch Arztebl Int 2010; 107(38): 657–62. VOLLTEXT|