Sleep duration linked to PCa mortality risk in younger men

Sleeping less than 7 hours per night is linked to increased risk of prostate cancer mortality in men younger than 65 years of age, but not among their older counterparts, according to a study presented at the American Association for Cancer Research annual meeting in Washington.

While previous research uncovered a similar association among employed men, this study looks at sleep duration and prostate cancer mortality risk in men regardless of employment status, said lead author Susan M. Gapstur, PhD, MPH, of the American Cancer Society in Atlanta.

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“In a previous analysis that was limited to employed men in the Cancer Prevention Study (CPS)-II, one of the American Cancer Society’s large prospective cohort studies, we found that sleeping 3 to 5 or 6 hours per night was associated with a higher risk of fatal prostate cancer compared to sleeping about 7 hours per night. We found this association only during the first 8 years of study follow-up and in men younger than 65 years of age,” Dr. Gapstur told Urology Times. “The purpose of this study is to expand on the earlier findings from CPS-II, by examining the association between sleep duration and prostate cancer death in a combined analysis of men in CPS-II and in an earlier cohort study, CPS-I, regardless of employment status.”

The results, she said, support a growing body of evidence that factors associated with circadian rhythm disruption might play a role in prostate carcinogenesis.

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The new analysis of 407,649 men from CPS-I, followed from 1950 through 1972, and 416,040 men from CPS-II followed from 1982 through 2012, suggests men younger than 65 years of age who got 3 to 5 hours of sleep a night were 55% more likely to die from the cancer than patients who got 7 hours of sleep. Even men who got 6 hours of sleep per night had an increased mortality risk. They had a 29% increased risk of death, compared to men sleeping 7 hours nightly.

All the men were prostate cancer-free at baseline, and they reported their sleep-related behaviors, including sleep duration. Nearly 1,550 died of prostate cancer in the follow-up for CPS-I and 8,704 died of the cancer in CPS-II.

The precise biologic mechanism for the increased mortality risk isn’t clear, but Dr. Gapstur said that sleep deprivation and the associated presence of light at night can inhibit the production of melatonin, a hormone that affects sleep cycles. Inhibition of this hormone has been linked to carcinogenesis.

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“The reasons for a lack of association between sleep deprivation and death from prostate cancer in older men are unclear, but might be related to the natural decline in nocturnal melatonin levels with age, possibly reducing the relative impact of sleep deprivation,” she said.

If these findings are confirmed in other studies, they could contribute to compelling evidence about the importance of obtaining adequate sleep for better health. In essence, the evidence suggests that getting adequate sleep is better for overall health, and may be good for prostate health, according to Dr. Gapstur.

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