Women who work in night shifts have a higher risk of developing breast cancer than those who work in day shifts, revealed a new study. Breast cancer is the major cause of mortality among women, which affect one hundred out of one hundred thousand women each year in developed nations.
In a bit to examine the effect of night work on the health researchers from Inserm (Institute National de la Sante et de la Recherche Medicale), investigated the routine of three thousand women in France between 2005 and 2008, including each period of night work.
The study found that women working in night shifts seemed to carry thirty percent higher risk of breast cancer, compared to those who worked during the day time. These negative effects were particularly marked in women who had worked nights for over four years, or in women whose working rhythm was less than three nights per week.
Researchers believe that disturbance in circadian cycle could be accountable for this association between breast cancer and working at night. Several oscillations in hormones such as melatonin could disturb its anti-cancer characteristics, thereby increasing body’s susceptibility to cancer. The constant switching on of light during the night shift appeared to block the production of melatonin hormone.
Lead author Pascal Guenel from Inserm, stated their work has corroborated the results of previous studies and poses the problem of taking night work into consideration in public health management, especially since the number of women working a typical hours is on the increase. Night shifts prior to first conception could increase the risk because the mammary cells before first conception are not completely differentiated.
These mammary cells are more vulnerable to acquire tumour. The study was published in the International Journal of Cancer.