Night or Rotating Shift Work Associated With Increased Risk for High PSA
Some data support an association between circadian disruption and prostate cancer. In a study reported in Journal of the National Cancer Institute, Erin E. Flynn-Evans, PhD, of the Division of Sleep Medicine at Brigham and Women’s Hospital, and colleagues assessed the association between night or rotating shift work and prostate-specific antigen (PSA) levels using data from the National Health and Nutrition Examination Survey (NHANES). They found that shift work was associated with significantly increased risk of elevated total PSA level and elevated total PSA combined with free PSA ≤ 25%.
Study Details
Three NHANES surveys (2005–2010) were combined to obtain current work schedule among employed men aged 40 to 65 years with no prior history of cancer except nonmelanoma skin cancer. Men who reported working regular night shifts or rotating shifts were considered “shiftworkers.” Total and percentage free PSA test results for these men were obtained from NHANES data.
The analysis included 2,017 men, of whom 233 were shiftworkers and 1,784 were nonshiftworkers. Shiftworkers were younger (mean age = 50.4 vs 51.4 years, P = .03), had shorter mean sleep duration (6.2 vs 6.7 hours, P < .001), worked more hours in the prior week (47.3 vs 44.3, P = .02), and were less likely to have health insurance (66% vs 75.5%, P < .001). Shiftworkers and nonshiftworkers also differed significantly in marital status (60% vs 72% married, 16% vs 10.5% divorced; P < .001), race/ethnicity (34% vs 47% white, 30% vs 18% black, 30.5% vs 31% Hispanic; P < .001), education level (15% vs 26% college graduates, P = .002), and annual household income (22% vs 15% < $20,000, 17% vs 26% > $75,000; P = .02). There were no differences between groups in height, weight, body mass index (BMI), proportion who were ever smokers, or proportion who had 12 or more alcoholic drinks per year.
Risk of Elevated PSA
Mean total PSA was 1.3 ng/mL in shiftworkers and 1.2 ng/mL in nonshiftworkers (P = .32). Overall, total PSA ≥ 4 ng/mL was found in 3% of subjects, including 5.6% of shiftworkers and 2.8% of nonshiftworkers. The age-adjusted odds ratio for elevated total PSA for shiftworkers vs nonshiftworkers was 2.48 (95% confidence interval [CI] = 1.08–5.70, P = .03). On multivariate analysis adjusting for age, BMI, race/ethnicity, health insurance, average hours of sleep per night, and months on the current job, the odds ratio was 2.62 (95% CI = 1.16–5.95, P = .02). The combination of total PSA ≥ 4.0 ng/mL and free PSA ≤ 25% was found in 5.6% of shiftworkers and 2.6% of nonshiftworkers. The age-adjusted odds ratio for this finding in shiftworkers vs nonshiftworkers was 3.10 (95% CI = 1.32–7.31, P = .01) and the odds ratio on multivariate analysis was 3.13 (95% CI = 1.38–7.09, P = .01).
The investigators concluded, “We observed a strong positive association with shiftwork and elevated PSA level. Our data support the notion that sleep or circadian disruption is associated with elevated PSA, indicating that shiftworking men likely have an increased risk of developing prostate cancer.”
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
