Much research has examined the effects of body mass index (BMI) on breast cancer risk and outcomes. A recent presentation at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting explored the effects of BMI on efficacy and side effects of the CDK4/6 inhibitor palbociclib, which is given at the same dose regardless of body weight.
The subanalysis, part of PALLAS (Palbociclib Collaborative Adjuvant Study), included 5,698 women with early breast cancer who were receiving a combination of the palbociclib and adjuvant endocrine therapy. The women were categorized as:
- underweight (BMI <18.5 kg/m2) (n = 68; 1.2%)
- normal weight (BMI 18.5–24.9 kg/m2) (n = 2,082; 36.5%)
- overweight (BMI 25–30 kg/m2) (n = 1,818; 31.9%)
- obese (BMI >30 kg/m2) (n = 1,730; 30.4%)
The researchers then analyzed adverse events and time to early discontinuation of therapy. They found significantly lower rates of all-grade neutropenia and less severe neutropenia (grade 3 or 4) in overweight and obese patients as compared with patients of normal weight.
Furthermore, lower rates of neutropenia among patients with higher BMI were correlated with lower rates of treatment discontinuation. However, no differences were found in time to invasive disease-free survival.
The authors, led by Georg Pfeiler, of the Comprehensive Cancer Center at the Medical University of Vienna in Austria, recommended additional research with longer follow-up to further clarify whether BMI affects long-term outcomes in this patient population.