Rotating Night Shifts, Sleep Duration, and the Risk of Colorectal Adenoma

Details

• Personal Author:
  Schernhammer E ; Wei EK
• Description:
  Night-shift work has been associated with cancer risk and is considered a "probable carcinogen". Occupation exposure to light at night, can lead to disrupted levels of melatonin, a hormone intimately involved in the body's internal clock and that has been shown decrease cancer cell growth in animal and laboratory studies. Disrupted melatonin levels likely increase the risk of developing cancer. Colorectal cancer (CRC) is the third most common cancer in the United States. CRC often starts first as an adenoma (polyp). Adenoma that are detected/removed will no longer develop into cancer. Night shift work has been associated with CRC, but few have evaluated whether night-shift work contribute to the early stages of CRC (e.g., adenoma). Studies suggest that habitual duration of sleep increases risk of death from cancer, cardiovascular disease, and other causes. However, only one prior study has evaluated sleep duration and colorectal cancer. We evaluated whether working rotating night shifts, habitual sleep, and directly measured melatonin levels were associated with colorectal adenoma. We used data from the Nurses' Health Study II (NHS II), a large cohort of over 116,000 women who have been followed biennially since 1989 for lifestyle, diet, medication use, and health outcomes. Using self-reported sleep duration and history of night-shift work, we analyzed whether longer duration of night shift-work or habitual sleep duration were associated with colorectal adenoma. We did not find any evidence of an association. We ran secondary analyses by sub-site within the colon, and also by the type of adenoma (low risk versus high risk), but did not observe any statistically significant variation in risk. We combined the null results from Aim 1 and Aim 3 into one manuscript that was published in 2017: "Rotating night shift work, sleep, and colorectal adenoma in women". We evaluated whether lower melatonin levels were associated with risk of distal colorectal. We assayed stored urine samples for melatonin (aMT6s) in a subset of our study population. Using a nested case/control design, we evaluated whether the risk of distal, high-risk colorectal adenoma (most likely to develop into cancer) varied by levels of aMT6s. We did not find any evidence of an association. We ran secondary analyses by subgroups of smoking and body mass index (BMI), and results were equivocal and non-statistically significant. We have prepared a manuscript of these results that will be submitted for publication. Although we found no evidence for an association between night shift work, sleep duration, urinary melatonin, and the risk of colorectal adenoma, we cannot rule out the possibility that these associations exist. Our study was limited by sample size, particularly for sub-group analyses. Next steps from this project include pooling our data with other data sources, accruing additional follow-up from this study, and/or evaluating other adenoma outcomes (multiple, serrated, etc.). We have generated valuable, novel data from the melatonin assays for future studies. Exposure to light at night and sleep remain important modifiable occupational risk factors for cancer; many opportunities still exist to intervene to improve worker safety in this area. [Description provided by NIOSH]
• Subjects:
  Carcinogens Endocrine System Health Personnel Neoplasms Occupational Health Safety Sex Characteristics Shift Work Schedule Sleep Women
• Keywords:
  Adenoma Author Keywords: Rotating Night Shift Work Colonoscopy Colorectal Cancer Gender Factors Hormones Nurses Nursing Polyps Risk Assessment Sex Factors Shift Work Tumors Work Schedules

  More +
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  California ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-23
• NIOSHTIC Number:
  nn:20052568
• NTIS Accession Number:
  PB2018-101655
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R21-OH-010204, 2017 Nov; :1-23
• Email:
  weie@cpmcri.org
• CAS Registry Number:
  Melatonin (CAS RN 73-31-4)
• Federal Fiscal Year:
  2018
• NORA Priority Area:
  Healthcare and Social Assistance
• Performing Organization:
  California Pacific Medical Center Research Institute, San Francisco
• Peer Reviewed:
  False
• Start Date:
  20130901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20170831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ccc62e72f8d1271e71eaf3e0513f0a45ccf57643bdad6d6ba81d4b0ff54097f6453bc066d00fde3c1cd3c82a7008fab74517f7f87006a00696fdc76b6917b2aa
• Download URL:
  https://stacks.cdc.gov/view/cdc/218711/cdc_218711_DS1.pdf
• File Type:
  [PDF - 215.81 KB ]