PHILADELPHIA — Men who reported sleep problems, including difficulty falling asleep and staying asleep, had up to a twofold increased risk for prostate cancer, according to data published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
"Sleep problems are very common in modern society and can have adverse health consequences," said Lara G. Sigurdardóttir, M.D., at the University of Iceland in Reykjavik. "Women with sleep disruption have consistently been reported to be at an increased risk for breast cancer, but less is known about the potential role of sleep problems in prostate cancer."
Previous studies have generated conflicting results for an association between sleep disruption from working night shifts and the risk for prostate cancer. Sigurdardóttir and her colleagues, therefore, investigated the role of sleep in influencing prostate cancer risk.
The researchers followed 2,102 men from the prospective Age, Gene/Environment Susceptibility-Reykjavik study, which involved an established, population-based cohort of 2,425 men aged 67 to 96. Upon enrollment into the study, the participants answered four questions about sleep disruption: whether they took medications to sleep, had trouble falling asleep, woke up during nights with difficulty going back to sleep or woke up early in the morning with difficulty going back to sleep.
Among the participants, 8.7 percent and 5.7 percent reported severe and very severe sleep problems, respectively. None of the participants had prostate cancer at study entry. The researchers followed the participants for five years, and during this period, 6.4 percent were diagnosed with prostate cancer.
After the researchers adjusted for age, they found that compared with men who reported no problems with sleeping, the risk for prostate cancer increased proportionately with reported severity of problems falling and staying asleep, from 1.6-fold to 2.1-fold. Further, the association was stronger for advanced prostate cancer than for overall prostate cancer, with more than a threefold increase in risk for advanced prostate cancer associated with "very severe" sleep problems.
To rule out the possibility that the problems with sleeping were because of undiagnosed prostate cancer or an enlarged prostate, the researchers reanalyzed the data after excluding men with symptoms of sleep disturbance that might be indicative of nocturia (waking up during the night to urinate). The results remained unchanged.
According to Sigurdardóttir, these data should be confirmed with a larger cohort with longer observation times. "Prostate cancer is one of the leading public health concerns for men and sleep problems are quite common," she said. "If our results are confirmed with further studies, sleep may become a potential target for intervention to reduce the risk for prostate cancer."
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Founded in 1907, the American Association for Cancer Research (AACR) is the world's first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 18,000 attendees. In addition, the AACR publishes eight peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the scientific partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of team science and individual grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www.AACR.org.