Linking Childhood Body Size to Breast Cancer Risk

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An intriguing new Swedish study linking heavier girls to decreased breast cancer risk highlights just how complicated the link is between body fat and cancer.

AICR’s expert report, along with other major reviews, have found clear evidence that excess body fat causes many different cancers, including post-menopausal cancer. And research shows that heavier children are more likely to become overweight adults.

But when it comes to cancer risk, studies are increasingly showing that there are “windows of susceptibility” – various periods during a person’s lifetime when diet, body fat, and physical activity exert a stronger than usual effect upon our risk of getting cancer.

These “windows” are one reason that the effects of lifestyle at an early age matter.

In this study, the researchers focused on girls at age seven. They showed about 6,000 adult women nine pictures of girls, ranging from skinny to obese body types. The women chose the picture that best resembled them when they were seven years old. About half of the women in the study had post-menopausal breast cancer.

The women who said they were bigger when younger were less likely to develop the disease overall, and also less likely to develop ER negative’ breast tumors, a form more difficult to treat. Even when the authors took into account other risk factors, such as adult BMI and estrogen exposure, the decreased risk held.

The study is published in the journal Breast Cancer; you can read it here.

As the authors note, the results appear counterintuitive to the evidence on body fat’s link to cancer.

Yet there have been some studies that showed a similar link between excess body fat in young girls and lower breast cancer risk, so scientists are looking at why. AICR has funded several scientists who are studying the role that childhood body fat plays on cancer risk, such as Leena Hilakivi-Clarke at Georgetown University.

For now, the best advice to lower cancer risk remains the same for girls, boys, the young adults and the elderly: eat healthy, stay physically active, and maintain a healthy weight.

Keep visiting AICR’s blog and Web site for the latest findings on childhood body fat, or other lifestyle influences, on cancer risk. What do you think about this study? Are there issues related to childhood body size and cancer that you would like to see funded?

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Author: Mya Nelson

Mya R. Nelson is at American Institute for Cancer Research, where she writes about the research in the field.

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