Tuesday, September 18, 2007

What has breast cancer survival to do with body fat?

women walking
Weight gain seems to be a risk at first sight, but it disappears when physical activity, nutrition and race are considered.

Obesity has been linked to a poorer survival in breast cancer patients, and one more of those studies have been published recently, suggesting that weight gain prior to breast cancer diagnosis can decrease survival. Compared to women who maintained their weight in a range of plus or minus three kilograms (six pounds), those who gained more than sixteen kilograms (35 pounds) from age twenty until one year before diagnosis had a double risk of mortality from breast cancer or from any cause.

Physical activity and nutrition more important than weight

At this point it is important to note that such a link or correlation does not imply a cause. In particular, no weight advice can be derived from this study. In order to learn more about the possible causes, we must have a closer look at other findings.

For instance, in a Californian study, physically active breast cancer patients with a high fruit and vegetable intake survived better, regardless of their weight. Many women of higher weight are less active and eat less fruit and vegetables, therefore weight seems to be linked to poor survival. But among the women with a healthy lifestyle, weight has no influence on survival. Being physically active and eating fruit and vegetables has found to reduce the risk by 50 percent with any weight.

The role of genes

We conclude: A healthy lifestyle may prevent weight gain in some women but not in others, and for these, their weight will not be a health problem.

Many more influences, such as genes, also play an important role in breast cancer risk and in body weight. A study in more than fifty thousand women has shown that body size has no negative influence on breast cancer risk in black women. On the contrary, a higher body mass (so-called "overweight") even lowers the risk of breast cancer in black women. White women, of course, cannot hope to profit from a similar genetic advantage.

Photo credit: flickr.com/photos/congvo/1395431872/

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