photo: telegraphuk
A US study, recently published, details findings of a much higher incidence of ovarian cancer in those women who worked the night shift as compared to those who worked day shifts.
The percentage of higher incidence was very significant, 49%, more than their day working counterparts.
The study was made with 3,000 women. However, many warn that this is a preliminary study that needs corroboration. But it has an interesting link to breast cancer, which was also found to be higher in night working women, although not in concomitance.
The current study demonstrated that there was a link between ovarian cancer and the work shift in the women studied. It showed that 25% of the advanced ovarian cancer illnesses were in women who worked the night shift, compared to 20% in the control group. That resulted in a 24% increase in advanced stage ovarian cancer and 49% in early stage disease for night workers.
However the results seem to point to an age differential in the incidence, with women over 50 being more affected. Also most of the women had worked the graveyard shift for two to three years in different industry sectors.
Scientists believe that melatonin levels might be at play. The hormone is only produced at night, so that in those women who are working into the wee hours the production is hampered or reduced. That in turn destabilizes the levels of estrogen, which has known cancer protecting factor in preventing DNA damage.
But those who work nights, might also have different eating habits or other factors which might be important in this study, so that further teasing of the data and corroborative studies are needed.
Another thing that oddly seemed important was whether the person was a day person or a night person, the so called chronotype of the individual. A person who called herself a night owl seemed to have less cancer than one who worked the night shift but called herself a day person, a person who likes to wake up early in the morning.
Scientists however, believe that the link could be reaffirmed in future studies and they point to the fact that the risk factor does not change with a longer night shift career in the women studied. However, women who do night work tend to have fewer or no children, which is also considered a risk factor for ovarian cancer by itself.
Source : BBc 3.15.13
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