MedicalResearch.com Interview with:
Parveen Bhatti, PhD
Fred Hutchinson Cancer Research Center
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Evidence in humans for an association between shift work and cancer has been mixed. This may be due to difficulties in accurately assessing long-term exposures to shift work in studies of cancer risk. We took a different approach that circumvented these difficulties. Rather than look at cancer risk directly, we measured, among actively employed shift workers, a marker of DNA damage that has been linked to cancer.
When repaired by cellular machinery, this particular marker is excreted in urine where it can be measured. We found that, compared to sleeping at night during their night off, shift workers had lower urinary levels of the DNA damage marker during their night work. This effect appears to be driven by reductions in circulating melatonin levels among shift workers during night work relative to night sleep. Given that melatonin has been shown to enhance repair of DNA damage, our results suggest that, during night work, shift workers have reduced ability to repair DNA damage resulting in lower levels being excreted in their urine. Because of this, shift workers likely have higher levels of DNA damage remaining in their cells, which can lead to mutations and cause cancer.