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Breast Cancer: Why Losing Weight Could Be a Matter of Life and Death

The Doctor’s Tablet Editors talked to the lead author of a paper in the journal Cancer that suggests a link between being overweight and the risk of  breast cancer recurrence, to better understand what this means for women with estrogren-receptor positive breast cancer – and their doctors.

A provocative paper published online this week in the journal Cancer shows that being overweight or obese puts breast cancer survivors with the most common type of breast cancer at significant risk for recurrence and death.

Being overweight or obese increases the chance that breast cancer will return

The main component of the paper’s three-study focus is a nationwide clinical trial that followed nearly 5,000 women with an average age of 53 years. Each participant had estrogen-receptor positive, HER2-negative breast cancer, the type that accounts for about two-thirds of all cases in the United States.

Researchers found that those with body mass indexes (BMI) of 30—the clinical threshold for obesity—had a 24 percent higher risk of breast cancer recurrence and a 40 percent higher risk of breast cancer death compared with non-obese women in the trial with the same type of breast cancer. This effect was seen even though all women in the study, irrespective of their weight, received state-of-the-art chemotherapy and endocrine treatments.

”I’m very concerned about these findings,” says the study’s lead researcher, Joseph Sparano, M.D., professor of medicine and of obstetrics & gynecology and women’s health at Einstein, associate chair of the department of oncology at Montefiore Medical Center and chief of the section of breast medical oncology at the Montefiore Einstein Center for Cancer Care. “This is really substantial, especially when you translate it into the tens of thousands of women who get breast cancer, many of whom are also obese.”

What’s especially notable is that all of the women at the start of the study had normal heart, liver, kidney and bone marrow function and no significant health problems other than their breast cancer. These results strongly indicate that the increased risk of recurrence and death was linked to excess weight and not to other medical problems or lesser adherence to standard treatments. The study also showed that the risk increased with increasing BMI when it rose above the overweight-but-not-obese range, defined as a BMI between 25 and 29.9. More than 70 percent of the women in the study were either overweight or obese.

Joseph Sparano, M.D.

Dr. Sparano says his research study and findings from other studies suggest that obesity is so common that it should be therapeutically targeted right when a woman learns she has breast cancer.

“We already know that maintaining a normal weight by adhering to a healthy lifestyle has many health benefits. We also know that a cancer diagnosis is a life-altering experience that provides a powerful incentive for change. The results of this study may provide an additional incentive for women diagnosed with breast cancer, especially estrogen-receptor positive breast cancer.”

Dr. Sparano and his colleagues believe that the stark findings could serve as a lifesaving wake-up call—for patients and doctors alike. He says specialists—including nutritionists, diabetes educators and oncologists—need to work more closely in interdisciplinary teams in order to focus on promoting healthier lifestyles.

“I think that in general, cancer specialists tend to have a tumor-centric view of managing cancer with a focus on treating or eradicating the tumor. There hasn’t necessarily been a lot of attention paid to health-related factors that can contribute to recurrence. “

In addition to the other benefits that healthy weight offers, Dr. Sparano says, some research indicates that reducing weight could reduce the risk of breast cancer recurrence. Scientists believe that there are many reasons why obesity may be driving recurrence.

“Obesity is associated with higher estrogen and insulin production, and also chronic low-grade inflammation. All three are proven to fuel growth of breast cancer cells, especially in estrogen-receptor positive breast cancers.”

Current studies are under way to examine the effectiveness of using drugs to reduce insulin levels and inflammation in those who have breast cancer in order to prevent recurrence.

For now, eating healthier and exercising regularly remain key. But given how difficult it is for people who are middle-aged and older to lose weight and keep it off, Dr. Sparano advises that breast cancer patients stay disciplined and take a long view.

“The reality is that this is an opportunity. But it’s much more difficult to get people to change their life habits on a continuing basis than it is to inject chemotherapy into their veins or get them to take a pill once a day.”

The new research showed no link between higher-than-normal weight and breast cancer recurrence among women with hormone-receptor negative breast cancers. However, Dr. Sparano says all women with breast cancer should maintain a healthy weight because of the overall wellness benefits. 

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