Night shift tied to lower prostate cancer risk among selected men

Men who carry the G allele of melatonin receptor 1B gene (MTNR1B) rs10830963 are at lower risk of prostate cancer when exposed to night shift work, according to a study.

Researchers examined the interaction between MTNR1B rs10830963 (which influences the dynamics of melatonin secretion) and night shift work (which disrupts internal circadian rhythms and dysregulates the production of melatonin) on prostate cancer in 133,416 employed male participants (mean age 53.13 years) from the UK Biobank.

The genotype distribution of rs10830963 was 52.8 percent for CC, 39.4 percent for CG, and 7.8 percent for GG. There were 15,298 (11.5 percent) male workers who reported taking night shift work. These men were younger and more likely to be of non-White ethnicity, have lower education, and not living with wife or partners. They also tended to be smokers but consume alcohol less frequently, obese, sleep for abnormal durations, have insomnia symptoms, and have the eveningness type.

In addition, fewer night shift workers reported a family history of prostate cancer and ever had prostate specific antigen tests than those without night shift work.

A total of 2,646 (1.98 percent) participants developed prostate cancer over a mean follow-up of 7.76 years, among whom 245 died because of prostate cancer over a follow-up of 12.17 years.

Analysis revealed a significant interaction between night shift work and MTNR1B rs10830963 on the incidence of prostate cancer (p=0.009). Among night shift workers, GC carriers had a significantly lower risk of prostate cancer (hazard ratio [HR], 0.69, 95 percent confidence interval [CI], 0.51–0.93), as did GG carriers (HR, 0.33, 95 percent CI, 0.15–0.75), compared with CC carriers.

Among non-night shift workers, rs10830963 polymorphism was not associated with the risk of prostate cancer.