SATURDAY, Aug. 20, 2005 (HealthDay News) -- New international research suggests that the small number of young women with a genetic propensity toward breast cancer could drastically reduce their risk by losing as few as 10 pounds.
The findings don't indicate whether dieting and exercise -- or a combination of both -- lower the risk of breast cancer in different ways. Nor do they provide guidance for those who don't have one of two genetic mutations.
"We're not sure what it means for other women," said study co-author Dr. Steven Narod, director of the University of Toronto's Familial Breast Cancer Research Unit.
Still, the research does appear to support the idea that weight and breast cancer are linked in some way, Narod said, perhaps through hormones that interact with gene mutations when a woman puts on weight.
An estimated one in 200 women has a mutation in at least one of two genes, known as BRCA1 and BRCA2. According to Narod, about 80 percent of these women will get breast cancer, compared to 8 to 10 percent of women without the mutation.
Apparently, Narod said, the genetic mutation disrupts the body's ability to repair itself when cancer strikes. Some groups of women seem to be at especially high risk of getting the genetic defect, including Ashkenazi Jewish women, those with a family history of breast cancer, and those with ovarian cancer.
The new study aimed to figure out how weight affects breast cancer risk. Narod and his colleagues studied two groups of 1,073 women from five countries. All had at least one genetic mutation making them susceptible to breast cancer; members of one group had been diagnosed with the disease, while the ones in the other group had not.
Each member of one group was then "matched" to a similar member of the other group from the same country.
The study findings were published Friday in the journal Breast Cancer Research.
Women with a mutation in the BRCA1 gene who lost at least 10 pounds between the ages of 18 and 30 were 65 percent less likely to develop breast cancer between 30 and 40 years of age.
But those who did the opposite -- gained 10 pounds between 18 and 30 -- were 44 percent more likely to get breast cancer if they also had two or more children.
The researchers couldn't find a connection between weight and the effects of the BRCA2 gene.
The study doesn't confirm that weight is directly linked to the women's likelihood of getting breast cancer; it only suggests a connection. It's possible the real cause of the fluctuations in breast cancer rates may be some other factor that influences weight, the researchers said.
Debbie Saslow, director of breast and gynecologic cancer with the American Cancer Society, said it's unclear whether the findings mean much for any women beyond the small number with the genetic mutations. Still, research has shown that weight gain raises the risk of breast cancer, she said.
According to Saslow, the "bottom line" is that appropriate weight loss is a good thing for all women. "It is recommended that all women strive for a healthy weight throughout their lives, and it may be a little more protective for women with a family history of breast cancer," she said.
More information
To learn more about genes and other breast cancer risk factors, visit the American Cancer Society.
