Sleep disruption, melatonin levels, and risk for prostate cancer

There have been a number of studies in the past suggesting that men who work night-shifts have a higher risk for prostate cancer than those of us who work during normal “day time” hours.

Now a new paper by Siggurdardottir et al. has suggested that there may, perhaps, be a close association between levels of 6-sulfoxymelatonin in a first morning void urine sample and subsequent risk for prostate cancer. However, as the authors are careful to point out, there are significant limitations to this study, and so we need to interpret these finding with considerable caution.

The data are based on a cohort of 928 Icelandic males who had no prior diagnosis of prostate cancer. Of these 928 men, 111 went on to be diagnosed with prostate cancer, and 24 were diagnosed with advanced forms of the disease.

Siggurdardottir et al. also note that:

  • Men who reported sleep problems at baseline had lower morning levels of 6-sulfoxymelatonin compared with those who reported no sleep problems.
  • Men with morning levels of 6-sulfoxymelatonin below the median level had a statistically significant, increased risk for advanced disease compared with men with levels above the median (hazard ratio [HR] = 4.04).

These results, however, are based on a single assay of morning levels of 6-sulfoxymelatonin in the 928 study participants (as opposed to several assays over a period of time).

What this study does tell us is that there is a possibility that there is some real increase in risk for clinically significant prostate cancer that is associated in some way with morning levels of 6-sulfoxymelatonin. What this study does not tell us is why there should be such an association; nor does it tell us that working night-shifts is necessarily associated with lower morning levels of 6-sulfoxymelatonin.

Having said that, it is likely that these data will stimulate further research into such associations and the possible, consequent, risk for clinically significant forms of prostate cancer.

3 Responses

  1. I have worked a lot of nights, never got a shift differential in pay, and then ended up with prostate cancer. Since finishing treatment, I have given up night work, mainly because I am too old, and I never liked it anyway. But my PSA has, thankfully, stayed low. I had never connected those things in my mind before. I guess the lesson is … keep your day job.

  2. Dear Dr. Hanline:

    I think we are going to need some more data before we start drawing radical conclusions based on the analysis of data from a relatively small number of Icelandic men in a epidemiological study of this type. However, for those who don’t like night work anyway, keeping one’s day job seems like a smart idea. For those who do like night work … keep watching this space!

  3. Both melatonin and vitamin D3 supplementation could be considered by male night workers as multiple studies of both seem to impact prostate cancer risk and both are day/night dependent.

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