HealthDay News — Men with higher levels of melatonin may have a lower risk of developing prostate cancer, according to researchers at the American Association for Cancer Research’s Conference on Advances in Prostate Cancer Research.

Risk for advanced prostate cancer was 75% lower in men with levels of 6-sulfatoxymelatonin — a measure of melatonin breakdown in urine — that were higher than the median value, Sarah C. Markt, MPH, from the Harvard School of Public Health in Boston, and colleagues reported.

They examined the association between urinary 6-sulfatoxymelatonin concentrations, sleep patterns and prostate cancer risk in 928 Icelandic men from the from the AGES-Reykjavik cohort from 2002 to 2009.

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Overall, 111 men were newly diagnosed with prostate cancer, including 24 with advanced disease. The median concentration of 6-sulfatoxymelatonin was 17.14 nanograms per milliliter.

One in seven men reported problems falling asleep, one in five men reported problems staying asleep, and almost one in three reported taking sleeping medications.

Levels of 6-sulfatoxymelatonin were significantly lower in men who reported sleep problems at baseline, the researchers found. Higher urinary 6-sulfatoxymelatonin levels were associated with a decreased risk of prostate cancer, particularly advanced disease. After adjusting for potential confounders, men with high levels of 6-sulfatoxymelatonin had a significantly lower prostate cancer risk (hazard ratio, 0.25).

“Our results require replication, but support the public health implication of the importance of maintaining a stable light-dark and sleep-wake cycle,” Markt said. “Because melatonin levels are potentially modifiable, further studies of melatonin and prostate cancer risk and progression are warranted.”


  1. Markt S. Abstract # A21, PR04. Urinary melatonin levels, sleep disruption, and risk of prostate cancer. Presented at: AACR Conference on Advances in Prostate Cancer Research. Jan. 18 to 21; San Diego, Calif.