# Sonographic Measurements of Rectus Femoris Muscle Thickness Strongly Predict Neutropenia in Cancer Patients Receiving Chemotherapy

## TL;DR

This study shows that measuring thigh muscle thickness with ultrasound can predict severe neutropenia in cancer patients undergoing chemotherapy.

## Contribution

Sonographic rectus femoris muscle thickness is a novel predictor of chemotherapy-induced neutropenia, independent of age, gender, and BMI.

## Key findings

- Low rectus femoris muscle thickness significantly increases the risk of grade ≥3 neutropenia in cancer patients.
- Ultrasound measurements of rectus femoris thickness can independently predict severe neutropenia with high accuracy.
- Threshold values of 18.0 mm for females and 20.0 mm for males were identified to predict severe neutropenia.

## Abstract

Individuals with cancer often experience a significant incidence of low skeletal muscle mass. This prospective cohort study, conducted between 2018 and 2020 in cancer patients undergoing anthracycline-based chemotherapy, aimed to explore the association between low skeletal muscle mass, measured by computed tomography (CT) and ultrasound (US), and hematologic toxicity. Regional muscle measurements were carried out using US, and hematologic adverse events were graded using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Results showed that low rectus femoris (RF) muscle thickness, determined by specific threshold values, significantly increased the incidence of grade ≥ 3 neutropenia. Regression analysis confirmed that low RF muscle thickness independently increased the risk of grade 3–4 neutropenia, irrespective of age, gender, and body mass index. This study suggests that utilizing US for measuring RF muscle thickness can help identify cancer patients at a higher risk of developing neutropenia, enabling more vigilant monitoring and timely implementation of supportive measures in clinical practice.

The objective of this study was to explore the possible association between low skeletal muscle mass (SMM)—assessed by computed tomography (CT) and ultrasound (US)—and hematologic toxicity in cancer patients. A prospective cohort study was conducted in cancer patients who received anthracycline-based chemotherapy between 2018 and 2020 and who had baseline abdominal CT including L3 level for measuring SMM. Regional muscle measurements were carried out using US. A total of 65 patients (14 males, 51 females) were included. ROC (receiver operating characteristic) analysis identified threshold values of 18.0 mm [AUC (area under the curve) = 0.765] for females and 20.0 mm (AUC = 0.813) for males, predicting severe neutropenia. Using these cut-offs, females with low rectus femoris (RF) thickness (<18.0 mm) had a significantly higher incidence of grade ≥3 neutropenia (50.0% vs. 10.8%, p = 0.005), and males with low RF values (<20.0 mm) had a higher incidence (80.0% vs. 22.2%, p = 0.063). A regression analysis, irrespective of age, gender, and body mass index, revealed that only low RF muscle thickness increased the risk of grade 3–4 neutropenia by 9.210 times (95% CI = 2.401–35.326, p = 0.001). Utilizing US to measure RF muscle thickness aids in identifying cancer patients at an elevated risk of developing neutropenia. Needless to say, US can serve as a convenient and easily accessible tool for assessing low SMM, providing repeat point-of-care evaluations in clinical practice.