HER2 Doesn't Like Extra Lbs

HER2 positive breast cancer treatment negatively impacted by obesity

(RxWiki News) Obesity has been a major topic at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium. Excess weight has been shown to be an aggravating factor on a number of fronts. Now, obesity is known to complicate the treatment of HER2-postive breast cancer.

Patients with HER2-positive breast cancer who are obese tend to have larger tumors, more lymph node involvement and poorer survival when they're not treated with Herceptin (trastuzumab). Those are the findings of a large, multi-center study presented at the conference.

"Herceptin improves outlook of obese HER2-positive patients."

In a first of its kind, this study looked at the relationship between obesity and HER2-positive treatment response and disease-free survival (DFS).

The study involved 3,017 patients who were placed into two groups - normal weight (BMI less than 30) and obese (BMI over 30). BMI was measured at the time patients started chemotherapy.

Participants were randomly assigned to receive one of three treatments: only chemotherapy; chemotherapy with sequential Herceptin; or chemotherapy with Herceptin given at the same time. Patients were followed for three, five and seven years.

The data at first saw no differences in DFS among the two groups in any of the three treatment arms. When researchers added patients who were overweight (BMI 25-29), this is what they found:

  • Obese and overweight patients who had not been treated with Herceptin had lower DFS rates, compared to normal-weight patients who received chemotherapy alone
  • DFS rates were about the same among all groups receiving Herceptin at the same time as chemotherapy.
  • Normal-weight patients benefit more from sequential Herceptin than obese patients.
  • All groups who did not receive the Herceptin had the worst DFS rates.

dailyRx spoke with Neil Spector, M.D., Co-Director of Experimental Therapeutics Program at the Duke Cancer Institute, about this study. "The bottom line is that weight management in obese women with breast cancer will likely affect multiple factors in women in a way that will hopefully increase the sensitivity of their tumors to chemotherapy and targeted therapies like Herceptin," Dr. Spector said.

"Breast cancer, like other cancers, is governed by host (patient) interactions with tumor cells. This is a complex system of interactions. Weight is only one aspect of this complex system among many others. Although some of these interactions are out of the patient’s control, weight management is something that can be controlled by the patient," Dr. Spector concluded.

Jennifer A. Crozier, M.D., a medical resident at Mayo Clinic in Jacksonville presented the results of this study at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.

Review Date: 
December 8, 2011