Joseph A. Sparano, MD
There is clear evidence that obesity at the time of diagnosis of operable breast cancer is associated with an increased risk of distant recurrence, specifically for hormone receptor (HR)–positive, HER2-negative disease, and oncologists should consider helping patients better manage their weight as part of their treatment plans, according to Joseph A. Sparano, MD.
These were among the conclusions that Sparano drew during a presentation at the 14th Annual International Congress on the Future of Breast Cancer® that Physicians’ Education Resource (PER®) hosted in Huntington Beach, California, July 16-19.
Sparano, who has studied the impact of obesity on patients with breast cancer extensively, is associate director of clinical research for Albert Einstein Cancer Center and chief of the section of breast medical oncology at the Montefiore Einstein Center for Cancer Care in New York.
Obesity is conventionally defined as a body mass index (BMI) of >30 kg/m2
. Sparano also noted that women with a BMI in the overweight range of 25 to 30 kg/m2
appear to have an increased risk of recurrence compared with women who have a normal BMI of 18.5 to 25 kg/m2
Since obesity is a major health problem in the United States, it is important for physicians to incorporate weight issues into disease analysis and treatment regimens, Sparano said. “More than a third of adults—72 million individuals—are obese. The obesity rates have increased two-fold in adults and three-fold in children since 1980,” he noted. Oncology researchers are starting to focus on ways to address the impact of excess weight for women with breast cancer. The Alliance for Clinical Trials in Oncology is about to initiate a randomized trial in women who have stage II/III breast cancer diagnosed within 12 months, are overweight or obese, and have completed their adjuvant systemic chemotherapy and radiation. The women will be randomized to a health and education intervention with a 2-year telephone-based weight loss intervention, Sparano said.
Sparano advised that physicians take steps now to help patients with their weight, such as recommending dietary and lifestyle interventions, even though such guidance is “not normally within the scope of activities of medical oncologists.”
The interventions he advocated included a weight management program modeled after the Diabetes Prevention Project that has been shown to significantly reduce the risk of developing adult onset diabetes in obese patients; it includes caloric restrictions and exercising at least 2½ hours per week, or about 30 minutes 5 days per week. Sparano cited a study published in the Journal of the American Medical Association
on July 15 indicating that exercise of 5 hours a week was even more effective in reducing adipose tissue.1Obesity a Factor in Poorer Outcomes
A number of factors can influence outcomes and treatment decisions in patients who are obese, Sparano said, including differing disease characteristics, comorbidities, and differences in adjuvant therapy administration.
“It is important that chemotherapy dosing be based on the actual weight and not empirically reduced,” he said. “There is clear evidence that capping chemotherapy doses is associated with a higher risk of recurrence, and is not effective in reducing chemotherapy-associated toxicity. In fact, an ASCO expert panel has specifically recommended weight-based dosing irrespective of BMI.”2
Given the multiple factors that could potentially contribute to worse outcomes in patients with breast cancer who are obese, Sparano and his fellow researchers attempted to disentangle these factors by taking a fresh look at the E1199 trial, which evaluated taxane doses and schedules for 4950 patients with breast cancer.3
“Our objective was to determine the relationship between BMI, clinical characteristics, and clinical outcomes,” defined according to breast cancer subtype as hormone receptor (HR)–positive, HER2 negative, HER2 positive, and triple negative, said Sparano. Patients were relatively healthy and were required to have normal cardiac, liver, and pulmonary function.
“When we looked at the characteristics of the obese versus nonobese subjects, we found that the obesity was associated with postmenopausal status, older age, black race, and somewhat greater use of breast conservation therapy. We found no significant differences in other characteristics, such as median tumor size, nodal status, estrogen receptor, progesterone receptor [PR], or the type of endocrine therapy administered,” Sparano said.