Sarcopenia detected with bioelectrical impedance versus CT scan and chemotherapy tolerance in patients with early breast cancer.

Background: Early breast cancer (EBC) is a potentially curable disease. Some patients with EBC require chemotherapy, exposing patients to undesirable side effects. Loss of muscle mass, or sarcopenia, has been associated with worse outcomes in patients with EBC and worse treatment-related toxicity in patients with advanced breast cancer. CT scans can identify sarcopenia; however, most patients with EBC do not require routine CT scans. Bioelectrical impedance spectrometry (BIS) is another method to detect sarcopenia and can be performed quickly in the office without radiation exposure. We sought to investigate whether sarcopenia measurements by CT scan versus BIS correlated with each other and whether sarcopenia identified by each method is associated with chemotherapy toxicity and adherence in patients with EBC.

Methods: This is a retrospective study; eligible patients received chemotherapy treatment for EBC and had undergone BIS. A subset of patients had also had a CT abdomen with a Lumbar L3 level. Measures of sarcopenia were obtained from the BIS and CT data. In addition, patient characteristics, treatment, and toxicity-related outcomes were obtained from medical records. Multivariate logistic regression models were used to associate sarcopenia status with toxicity endpoints, adjusted for other patient characteristics.

Results: There was a moderate correlation between sarcopenia detected by CT scan and BIS (r = 0.64 p < 0.0001). Patients with sarcopenia detected by BIS had more chemotherapy toxicity (OR = 2.56; CI 1.72-3.84), dose reductions or dose delays (OR = 1.58; CI 1.06-2.38), and hospitalizations (OR = 2.38; CI 1.33-4.16) due to side effects than patients without sarcopenia.

Conclusion: The presence of sarcopenia in patients with EBC is associated with worse chemotherapy tolerance. BIS represents a high-value alternative to CT scans for sarcopenia assessment.