Women who use sunbeds more than once a month for several decades had a 37 percent lower risk of contracting breast cancer, according to a new prospective study of nearly 50,000 Swedish women followed for 15 years — a strong addition to data suggesting that the benefits of regular UV exposure from any source outweigh the manageable risks of overexposure.

Researchers at the University of Oxford in England, the University of Oslo in Norway, The Karolinska Institute in Sweden and the Harvard School of Public Health in the United States published the study in the peer-reviewed journal Cancer Epidemiology, Biomarkers and Prevention on-line this week. The study shows that women who spent more than 1 week a year on sunbathing vacations between ages 10-29 had a 30 percent lower overall risk of any internal cancer — and 44 percent fewer breast cancers — compared to non-tanning women.

“UV exposure earlier in life was related to reduced overall and breast cancer risk,” the authors reported. “Further research is needed to define the amount of solar or artificial UV exposure that may, or may not, be beneficial for cancer prevention.”

While the data did not suggest that cumulative UV exposure was protective, the authors believe that the vitamin D pathway inherent with UV exposure is the likely mechanism responsible for cancer risk reduction for those who sought sunlight or sunbeds.