BMI Impacts Neutropenia, Treatment Discontinuation in Breast Cancer

Body mass index (BMI) had an effect on side effects, dose reductions, early treatment discontinuation and relative dose intensity for patients with early hormone receptor (HR)-positive breast cancer, according to findings from the recent PALLAS trial.

“Obesity is a major health issue, especially in industrial countries. About two-thirds of postmenopausal patients and one-third of premenopausal patients with breast cancer are overweight or obese at the time of diagnosis. Obesity promotes the development of various diseases like diabetes mellitus or coronary heart disease in postmenopausal women and is associated with an increased risk of breast cancer,” explained Dr. Georg Pfeiler, Medical University of Vienna, in a recent interview with CURE®. 

Pfeiler mentioned that several issues are important to address within BMI in general such as: How does BMI impact on various diseases, how can we overcome the impact of BMI on a special disease like breast cancer, is therapy necessary and different for obese patients compared to normal weight patients, or is another dose of treatment needed? BMI’s effects with different diseases leave questions unanswered.

The PALLAS trial focused on the effects of BMI when it came to neutropenia in patients with breast cancer being treated with or without Ibrance(palbociclib).

“Neutropenia is state with a low amount of neutrophil granulocytes in the blood. The neutrophil granulocytes are a distinct part of the white blood cells which are especially important in the defense of infectious diseases. A patient with a neutropenia has a high risk of getting an infectious disease with fever”, explained Pfeiler. “Neutropenia is a typical severe side effect of chemotherapy and a typical but not that severe side effect of a CDK 4/6 inhibitor.

A total of 5,698 patients within the study were assigned to undergo adjuvant endocrine treatment (ET) for at least five years with or without Ibrance in the span of two years. The primary endpoint of the study was to investigate invasive disease-free survival (iDFS).

Within the study, 68 patients were underweight (1.2%), 2,082 patients were normal weight (36.5%), 1,818 patients were overweight (31.9%) and 1,730 patients were obese (30.4%). For patients who received Ibrance, the population of patients with higher BMIs experienced lower rates of neutropenia. Additionally, patients with a higher BMI also had lower treatment discontinuation rates. When it came to iDFS, there was no change when adding Ibrance to ET within all weight categories.

“There can be side effects of a certain treatment that may be more or less severe in obese patients when compared to normal weight patients. In our work, we showed that overweight and obese patients derive less neutropenia — which is a common side effect from the CDK 4/6 inhibitor (Ibrance)— when compared to normal-weight patients. This might be due to a reduced tissue/blood concentration of the drug in overweight/obese patients or overdosage in the normal weight patients. We think therefore it is important to give the dosage of a drug in dependence of the BMI,” explained Pfeiler.

Although less neutropenia can be seen within overweight patients, there are still side effects that can be experienced within these weight categories.

BMI levels can be lowered by exercise and nutrition patterns, according to Pfeiler.

“The energy intake (so whatever amount of calories you drink or eat) should be less when compared to the energy you spend (by just living, but also sports), or the other way around (spend more energy than you eat or drink),” Pfeiler said.

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