Working nights reduces skin cancer risk

Hi all

I found this quite interesting. Night workers have an increased risk of cancers generally but not skin cancers. I wonder if it is due to reduced sun exposure or something else?



BOSTON, March 3 (UPI) — Working nights is linked to increased risk of some cancers, heart disease and diabetes, but workers may have less risk of skin cancer, U.S. researchers say.

Lead author Dr. Eva Schernhammer of the Channing Laboratory at Brigham and Women’s Hospital in Boston documented 10,799 incidents of skin cancer in 68,336 women in the Nurses’ Health Study over an 18-year period.

The study, published online in the Journal of the National Cancer Institute, found higher duration of working rotating night shifts was associated with a significantly lower risk of skin cancer.

Although the risk for each skin cancer — basal cell carcinoma, squamous cell carcinoma and melanoma — decreased, the strongest association was observed for melanoma, which was associated with a 44 percent decreased risk of melanoma after working shifts for 10 years.

Working night shifts has been linked to decreased production of melatonin, which is known to have cancer-protective properties.


  1. #1 by hein vandenbergh on March 4, 2011 - 7:03 am

    Yeah, interesting stuff – but a lot of confounding variables. Less exposure to sunlight may, in fact, increase individual melanoma risk, as was demonstrated in a Finnish study about 15 yrs ago. Not a great deal of exposure all year, then 3 weeks baking in Spain –> high incidence of melanoma. Regular, non-excessive exposure to UV induces a DNA repair mechanism. Night workers who sleep during the day may have ‘unprepped’ skin, then they go into a weekend of surfing and SHOULD have more melanomas – but in this study they do not. Also, their Vit D levels are likely to be lower. Which meand less, not more, protection.

    Thus, I think (lack of) exposure is not the factor at play here, but some sort of hormonal change related to an alteration of circadian rhythm. Melanotonin is one of the obvious suspects, but what do we know about HGH (circadian fluctuation) and carcinogenesis? What about alterations in ‘normal’, circadian or physiological cortisol production, possibly affecting the immune system and its response to neoplasia?

    It talks about a ‘significant’ reduction etc – I’d like to see the stats, confidence intervals etc. I think we need to correlate these findings with things such as reductions/increases in the various hormones and other ‘humeral’ substances to try and get a fix on this fascinating finding.

    Meanwhile, I’ll keep going to bed at night and to work/play during the sunlight hours!

    Thanks, Ian – food for thought.

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