Contrary to what scientists previously believed, a study by German researchers has suggested that rotating shift work has no effect on the occurrence of prostate cancer. The results of their study were published in the Deutsches Ärzteblatt International journal.
Recent studies have shown that employees who work in rotating shifts may be more susceptible to cancer than salaried employees working traditional daytime hours. In particular, research has suggested this may be the case in regard to breast cancer.
Yet very few studies have looked at the connection between rotating shift work and the risk of prostate cancer.
Which is what a team from the Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI) at the University Medical Center of the Johannes Gutenberg University Mainz, under the direction of Dr P H Hammer, attempted to do.
According to the authors of the study, "While the literature contains evidence that shift work that involves circadian disruption increases the risk of breast cancer, and some studies have reported an increased risk of prostate cancer, this study found no difference between shift and daytime workers."
Comparable numbers in both groups
To reach their conclusion, the scientists studied a total of 27.828 male industrial production workers (15.219 daytime and 12.609 shift) residing in the German federal state of Rhineland-Palatinate who worked for at least one year in a chemical company in the period 1995-2005.
The results, published in the Deutsches Arzteblatt International journal, indicate that during the 10-year study period (270.068 person-years), 555 and 518 cases of cancer were observed in daytime and shift workers respectively, of which 191 and 146 respectively were prostate cancers.
The authors of the study concluded that "In addition to the size of the cohort, the strengths of this study included its documentation, based on personnel files and medical records. This means that recall bias can be ruled out. One feature of the cohort is the balanced numbers of daytime and shift workers from the same parts of the company and with the same working conditions, making them comparable in terms of risk profile, age distribution, and socioeconomic status. This maximized the power of internal comparisons and at the same time minimized the risk of bias caused by other work-related factors."
Because the median year of birth was 1960 in the first group and 1959 in the second, in the authors' opinion, further follow-up of this relatively young cohort is required.