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Body Mass Index Linked to Some Breast Cancers

CancerWise - May 2008

Women diagnosed with inflammatory breast cancer (IBC) and locally advanced stages of breast cancer (LABC) who had a high body mass index (BMI) had a worse prognosis than women who maintained a healthy BMI, according to a study published in the March 15 issue of Clinical Cancer Research.

BMI is a measure of body weight in relation to height and can be calculated through the National Institutes of Health Web site.

Significance of results

"Before BMI is completely accepted as a prognostic tool for breast cancer, prospective trials and endocrinology studies must be conducted," says the study's lead author Massimo Cristofanilli, M.D., associate professor in M. D. Anderson’s Department of Breast Medical Oncology. "However, to oncologists currently treating overweight and obese patients with LABC and IBC, they should be more aggressive in follow-up, consider more frequent physical exams and imaging studies."

Cristofanilli also says that going on a diet might be difficult for women undergoing chemotherapy, but healthy lifestyle habits after diagnosis are vital.

Goal of study

"We embarked on this research because the vast majority of our newly diagnosed inflammatory breast cancer patients were overweight or obese, and IBC is associated with a poor prognosis," Cristofanilli says. "The idea was to understand the link between the most aggressive forms of breast cancers and, ultimately, prognosis."

Background

IBC is a rare and aggressive form of breast cancer and is often mistaken as a rash or a breast infection. IBC represents 1% to 2% of all breast cancers diagnosed in the United States.

LABC is cancer that has spread to nearby tissue or lymph nodes.

In the United States each year, LABC represents about:

  • 5% of newly diagnosed patients
  • 50% of newly diagnosed patients in underserved communities

Research methods

Researchers reviewed the medical files of women with LABC and
non-metastatic IBC (cancer that has not spread from the primary cancer site) who were enrolled in clinical protocols at M. D. Anderson between 1974 and 2000.

Of the 606 patients studied:

  • 82% had been diagnosed with LABC
  • 18% had been diagnosed with IBC

Of the participants:

  • 34% were a healthy weight or underweight
  • 32% were overweight
  • 34% were obese

All patients received similar chemotherapy treatments. The doses were not adjusted based on a patient's weight.

Obesity was more frequent in women with IBC (45%) than those with non-IBC (31%), Cristofanilli says.

The median follow-up for the study was:

  • 6 years for all patients
  • 9.9 years for women who were still alive

Primary results

The overall median survival rates were significantly worse for overweight and obese patients with LABC and IBC compared to those who were of normal weight or underweight, Cristofanilli says.

Overall survival rates for the LABC groups are as follows:

Of the overweight LABC patients: 58.3% had a five-year survival rate. Of those survivors, 44.1% lived another five years.

Of the obese LABC patients: 58.6% had a five-year survival rate. Of those survivors, 42.4%, lived another five years.

Of the normal-weight and underweight LABC patients: 69.3% had a five-year survival rate, and 57.3% lived another five years.

Overall survival rates for the IBC groups are as follows:

Of the overweight IBC patients: 45.3% had a five-year survival rate, and 29.1% lived another five years.

Of the obese IBC patients: 49.3% had a five-year survival rate, and 43.7% lived another five years.

Of the normal-weight and underweight IBC patients: 55.1% had a five-year survival rate, and 50.9% lived another five years.

What’s next?

Researchers need to look at the relationship between obesity and hormonal factors that may explain why patients with IBC are more frequently obese, Cristofanilli says.

"Our next step is to go back to the lab and start looking into those specific factors related to obesity in breast cancer," he says. "Hormones that are of immediate interest are insulin (regulates blood sugar), estrogen (regulates female reproductive system) and leptin (regulates appetite and metabolism)."

- Adapted by Deborah Aranda from an M. D. Anderson news release

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© 2014 The University of Texas MD Anderson Cancer Center