Melatonin found to lower risk of prostate cancer

Melatonin, a hormone involved in the sleep-wake cycle often taken as a supplement, may reduce the risk for developing advanced prostate cancer, a new Harvard University study has found.

According to findings presented at a meeting of the American Association of Cancer Research in San Diego, medical investigators from the Harvard School of Public Health in Boston who tracked nearly 1,000 Icelandic men found those with higher levels of melatonin were far less likely to develop aggressive prostate cancer than those with lower levels of the hormone.

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The findings, presented at the AACR-Prostate Cancer Foundation Conference on Advances in Prostate Cancer Research, suggests melatonin plays a role in regulating other hormones that influence certain cancers, including breast and prostate cancers.

The hormone is produced at night in the dark and helps regulate the body’s internal 24-hour clock, which is why many people take it to help them get to sleep.

“Sleep loss and other factors can influence the amount of melatonin secretion or block it altogether, and health problems associated with low melatonin, disrupted sleep, and/or disruption of the circadian rhythm are broad, including a potential risk factor for cancer,” said Sarah C. Markt, a doctoral candidate in the Department of Epidemiology at Harvard School of Public Health in Boston.

“We found that men who had higher levels of melatonin had a 75 percent reduced risk for developing advanced prostate cancer compared with men who had lower levels of melatonin.”

Markt said more study is needed, but added that the results “support the public health implication of the importance of maintaining a stable light-dark and sleep-wake cycle.”

For the study, the Harvard team tracked byproducts of melatonin in the urine of 926 men over a seven-year period and compared them to their risk of prostate cancer. The researchers found that 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.

The results showed that 111 men were diagnosed with prostate cancer, including 24 with advanced disease. The researchers found those with higher than normal levels of melatonin had a 31 percent decreased risk for advanced prostate cancer and a 75 percent lower risk of developing an aggressive form of the disease.

“Further prospective studies to investigate the interplay between sleep duration, sleep disturbance, and melatonin levels on risk for prostate cancer are needed,” said Markt.