Research Links Night Shift Work to Increased Haematopoietic Cancer Risk

Overview of Haematopoietic Cancers

Recent research, the largest of its kind, has established a connection between long-term night shift work and a heightened risk of haematopoietic cancers. These cancers, including leukaemia and lymphoma, target immune system cells found in the blood, bone marrow, lymphatic system, and lymph. In the United States, a new case of haematopoietic cancer is diagnosed every three minutes, constituting 10% of all new cancer cases.

Understanding the Research Study

While each type of haematopoietic cancer has unique risk factors, the underlying causes often remain elusive. To better understand these risks, researchers explored the relationship between rotating night shift work and the likelihood of developing haematopoietic cancer. Their findings were published in the JNCI Cancer Spectrum, drawing from data collected in the United States Nurses’ Health Study and Nurses’ Health Study II—ongoing studies involving female registered nurses.

The first Nurses’ Health Study enrolled over 120,000 participants aged 30 to 55 years, while Nurses’ Health Study II included more than 115,000 participants aged 25 to 42 years. The study revealed that nurses who worked rotating night shifts for over 15 years exhibited a significantly greater risk of developing haematopoietic cancer.

Investigating the Mechanism Behind the Risk

This correlation raises questions about how night shift work might contribute to increased cancer risk. In 2019, the International Agency for Research on Cancer classified night shift work as a probable carcinogen. Previous research has highlighted the potential carcinogenic effects of disrupting the body’s circadian rhythms.

One speculation is that night shift work may inhibit melatonin production, a hormone essential for regulating the sleep-wake cycle and acting as a powerful antioxidant that protects cells from damage caused by free radicals. Furthermore, individuals engaged in prolonged night shift work may tend to be older, have elevated body mass indexes, consume higher energy levels, smoke more frequently, and use specific medications—all factors that could influence cancer risk.

Need for Caution and Further Research

Various occupational, environmental, lifestyle, and physiological elements might elucidate the link between night shift work and a higher occurrence of haematopoietic cancer. However, the researchers advise caution in interpreting these findings, emphasizing the necessity for more extensive studies to deepen the understanding of the association between rotating night shift work and haematopoietic cancer.

References

– Lls.org. (2020). Facts and Statistics | Leukemia and Lymphoma Society. Available at: https://www.lls.org/facts-and-statistics/facts-and-statistics-overview/facts-and-statistics [Accessed 14 Jan. 2020].
– Ward, E., et al. (2019). Carcinogenicity of night shift work. The Lancet Oncology, 20(8), pp.1058-1059.
– Zhang, Y., et al. (2020). Rotating nightshift work and hematopoietic cancer risk in U.S. female nurses. JNCI Cancer Spectrum.