MADRID, 2 Feb. (EUROPA PRESS) –
Working outdoors for many years is linked to a lower risk of breast cancer in women after the age of 50, according to research published online in the journal Occupational & Environmental Medicine.
Outdoor workers are exposed to more sunlight, which increases their levels of vitamin D, which can protect against illness, the researchers explain.
Vitamin D has a well-recognized role in maintaining bone and musculoskeletal health, but it may have other roles, including helping to prevent infection and cancer.
The main source of vitamin D is UVB rays from the sun. However, concerns about skin cancer risk and the increasing use of computers for both work and play have reduced the amount of time people spend outdoors.
The increasing incidence of breast cancer during the last half of the 20th century has led to the suggestion that this could be related to vitamin D deficiency.
Previous research indicates that higher levels of vitamin D in the blood may be associated with a lower risk of breast cancer, but the evidence is not conclusive.
Most studies have relied on limited assessments of vitamin D levels rather than looking at long-term levels.
Exposure to sunlight can be used as a surrogate marker for long-term vitamin D levels, and since the body produces vitamin D mainly in the middle of the workday (between 10 a.m. and 3 p.m. afternoon), outdoor workers are exposed to considerably higher levels than those working indoors.
The researchers identified 38,375 women under the age of 70 who had been diagnosed with primary breast cancer from the Danish Cancer Registry. They compared each of them with five women born in the same year and randomly selected from the Danish Civil Registration System.
Full employment history was retrieved from Danish pension fund records and an occupational exposure matrix was used to assess each woman’s occupational exposure to sunlight.
After taking into account potentially influential factors, such as reproductive history, no association emerged between occupational exposure to sunlight and overall risk of breast cancer.
But long-term occupational exposure was associated with a lower risk of breast cancer after age 50.
In these women, occupational exposure for 20 years or more was associated with a 17% lower chance of a breast cancer diagnosis, while the highest cumulative exposure level was associated with an 11% reduced chance.
This is an observational study, so you cannot establish the cause. However, the researchers conclude that “this study indicates an inverse association between long-term occupational exposure to sunlight and late-onset breast cancer. This finding needs more attention in future occupational studies,” they claim.
–
