Last Updated: 2007-12-21 12:00:38 -0400 (Reuters Health)

By Megan Rauscher

NEW YORK (Reuters Health) - Results of a Swedish study of mainly premenopausal women at enrollment does not provide any evidence that total dietary fat or intake of monounsaturated fat (MUFA), polyunsaturated fat (PUFA), or saturated fat (SFA) is associated with a woman's overall risk of developing breast cancer.

However, according to Dr. Marie Lof from the Karolinska Institute, Stockholm, "Our results suggest that types of fat (MUFA, PUFA, SFA) may have different effects on risk between breast cancer occurring before and after age 50 years."

"Such a finding has not been reported before," she told Reuters Health, adding: "There is no apparent explanation for this finding and further studies are warranted."

The Swedish study involved 44,569 women of normal weight at enrollment, at which time their fat intake was assessed. During an average follow up of 13 years, 974 women developed breast cancer.

Lof and colleagues report in the British Journal of Cancer that total fat, MUFA, PUFA, and SFA were not associated with breast cancer risk overall.

However, women reporting the highest MUFA and PUFA intake had a markedly reduced risk of breast cancer after age 50 years compared to women with the lowest MUFA and PUFA intake.

Summing up, Lof and colleagues note that despite the overall negative findings in this study, it's possible the type of fat during premenopausal years "may have later differential effects on risk."

SOURCE: British Journal of Cancer, November 27, 2007.