Strength-to-muscle radiodensity: A potential new index for muscle quality.

BACKGROUND & AIMS: Although it is widely recognized that muscle quality significantly influences adverse outcomes in patients with cancer, the precise definition of muscle quality remains elusive. The muscle quality index (MQI), also known as muscle-specific strength, is a relatively recent functional concept of muscle quality. It is obtained through the ratio of muscle strength to muscle mass, but its predictive value in patients with cancer remains unknown. In this study, we explored the prognostic significance of MQI in patients with cancer. Furthermore, we introduce and assess the prognostic potential of a novel muscle quality metric: the strength-to-muscle-radiodensity index (SMRi). METHODS: A secondary analysis was conducted on a prospective cohort study. CT scans were opportunistically used to assess body composition parameters, including skeletal muscle mass (SM in cm2) and muscle radiodensity (SMD in HU) at the third lumbar vertebra (L3). Handgrip strength (HGS) was measured. MQICT was calculated using the ratio of HGS to SM (cm2). SMRi was calculated as the ratio of HGS to SMD (HU). For analysis purposes, low MQICT and SMRi were defined using two approaches: statistical cutoffs associated with survival, and median-based distribution data. RESULTS: A total of 250 patients were included (52.8% females, 52% adults, 20-90 years). Gastrointestinal tumors and stage III-IV were the most frequent diagnosis and stages. SMRi and MQICT were strongly positively correlated (ρ = 0.71 P < 0.001). Individual components of MQICT and SMRi were also positively correlated. Patients with both low MQICT and SMRi had shorter survival (log-rank P = 0.023 and P = 0.003, respectively). When applying median distribution cutoffs, SMRi emerged as the most accurate predictor of mortality (HR adjusted 3.18, 95% CI 1.50 to 6.75, C-index: 0.71), when compared to MQICT (HR adjusted 1.49, 95% CI 0.77 to 2.87, C-index: 0.68). CONCLUSION: This study introduces the concept and potential prognostic significance of the SMRi. The physiological and clinical implications of this new index warrant further investigation across a spectrum of diseases, including cancer.

Comparative assessment of abdominal and thigh muscle characteristics using CT-derived images.

OBJECTIVES: The aim of this study was to compare the assessment of skeletal muscle area (SMA in cm²), skeletal muscle index (SMI in cm²/m²), and skeletal muscle density (SMD in HU) between third lumbar vertebra (L3) and thigh landmarks, and the agreement in diagnosing low muscle mass and low SMD (L3 as the reference method). METHODS: This was a multicenter, cross-sectional study including healthy individuals (≥18 y of age) of both sexes, who had an elective computed tomography exam including abdominal and pelvic regions. Computed tomography images were analyzed to evaluate SMA, SMI, and SMD. Muscle abnormalities (low SMA, SMI, and SMD) were defined as values below the fifth percentile from a subsample of healthy young individuals (n = 111; 18-39 y of age; 55.9% women). Correlation coefficients, Bland-Altman graphs, and receiver operating characteristic (ROC) curves were calculated for the total sample and stratified by sex and age. RESULTS: In all, 268 individuals (44.3 ± 15.2 y of age) were evaluated (53% women). Significant (P < 0.001 for all analysis) and strong correlations between SMA (r = 0.896), SMI (r= 0.853), and SMD (r= 0.864) compared with L3 and thigh landmarks were observed. For the ROC curves, similar areas under the curve values were obtained for men (0.981), women (0.895), younger (0.902), and older adults (0.894). CONCLUSIONS: Muscle characteristics between L3and thigh landmarks have a strong correlation. This suggests that images of the thigh can be used to characterize muscle characteristics. Image acquisition and analysis of thigh region is simpler, with less radiation exposure, and consequently more appropriate for longitudinal analysis.

Low calf circumference is an independent predictor of mortality in cancer patients: A prospective cohort study.

OBJECTIVE: Loss of muscle mass is associated with worse outcomes in patients with cancer. The objective of this study was to evaluate the prognostic value of calf circumference (CC) and skeletal muscle index from computed tomography (CT) to predict mortality in patients with cancer. METHODS: A single-center prospective study was conducted with patients aged ≥20 y attending a reference center of oncology and who had recent abdominal CT images. Data were collected through a semistructured form and patients' records and included sociodemographic data (sex, age and ethnicity), clinical data (primary site and staging of tumor and treatments performed), anthropometric variables (body mass index and CC), and outcome (death). Low CC for men was considered to be ≤ 34 cm and for women ≤ 33 cm. Muscle mass was assessed by CT images at the level of L3. The Cox proportional hazard model adjusted for age, sex, and staging of disease was used. RESULTS: A total of 250 patients were evaluated, 52.8% female, with a median age of 63 y (interquartile ratio: 55-73). Normal body mass index was identified in 44.4%; 29.2% had low skeletal muscle index, and 46.4% had low CC. Death by any cause occurred in 16%, and only low CC was a significant predictor of mortality (hazard ratio = 3.01; confidence interval 1.52-5.98; P = 0.002). CONCLUSIONS: Low CC can predict risk of mortality in this cohort of patients. The findings suggest the use of CC as a simple, easy, cost-effective anthropometric measurement to quickly screen patients at risk of death who could benefit from targeted care to improve their prognosis.

Is skeletal muscle radiodensity able to indicate physical function impairment in older adults with gastrointestinal cancer?

BACKGROUND: Worsening nutritional status in older adult cancer patients can lead to sarcopenia, a condition that occurs with low quantity or quality of muscle mass associated with low physical function. However, most of the studies with cancer patients have only analyzed the quantity of muscle mass for diagnostic of sarcopenia, without exploring muscle characteristics and physical function. The purpose of the present study is to explore the associations between muscle mass characteristics and physical function in older adult patients with cancer. METHODS: Gastric older cancer patients were enrolled in a cross-sectional study. Computed tomography images of the abdominal region evaluated skeletal muscle mass using the Slice-O-Matic version 5.0 Software program (Tomovision, Montreal, Canada) to determine the parameters of skeletal muscle index (SMI, muscle quantity) and skeletal muscle radiodensity (SMD). The physical function was evaluated through handgrip strength and gait speed test. Four musculature phenotypes were identified: normal SMI and SMD, only low SMI, only low SMD, and low SMI and SMD. Linear regression analyses adjusted by age and tumor stage verified the associations between SMI, SMD and physical function. A One-Way Covariance Analysis with Bonferroni post hoc test was used to compare the physical function variables among the four different phenotypes. RESULTS: In total, 167 patients were evaluated (58.1% males; mean age 69.17 ±â€¯7.97 years). The results showed that muscle mass characteristics explains, at least partially, the variability in handgrip strength and gait speed in a direct relationship. The phenotypes with low muscular SMI and/or SMD presented worse performances in handgrip strength and gait speed tests. When stratified for sexes, the significant difference occurs only in males. CONCLUSIONS: Low SMD has negatively impacted physical function in older adults with gastrointestinal cancer, especially in males.

Is cachexia associated with chemotherapy toxicities in gastrointestinal cancer patients? A prospective study.

BACKGROUND: Chemotherapy is an effective treatment with good clinical response in patients with cancer. However, it can cause exacerbated toxicities in patients and consequently change the course of treatment. Some factors may interfere with this toxicity such as body composition, especially in gastrointestinal cancer. The aim of this study was to evaluate the effects of body composition, nutritional status, and functional capacity scale in predicting the occurrence of toxicities in gastrointestinal cancer patients during chemotherapy treatment. METHODS: This is a prospective study with gastrointestinal cancer patients at the beginning of chemotherapy treatment. Sarcopenia and muscle attenuation were assessed using the skeletal muscle index from computerized tomography by measuring cross-sectional areas of the L3 tissue (cm2 /m2 ). Cachexia was graded according to involuntary weight loss associated with sarcopenia. Nutritional status was assessed by using anthropometric evaluation and Patient-Generated Subjective Global Assessment. Functional capacity was evaluated by handgrip strength and Eastern Cooperative Oncology Group (ECOG) Performance Status scale. Haematological gastrointestinal and dose-limiting toxicities (DLTs) were defined according to National Cancer Institute Common Toxicity Criteria. The associations among sarcopenia, cachexia, nutritional status, and functional capacity with DLT were assessed by univariate and multivariate Cox regression model. RESULTS: A total of 60 patients were evaluated (55% male, 60.9 ± 14.0 years) and followed up for a mean of 55 days. Most patients had normal weight (44.2%) and good ECOG Performance Status (≤1) at baseline (78%). During the chemotherapy period, the most prevalent toxicities were diarrhoea, nausea, and anorexia, but the presence of DLT was similar between cycles (P > 0.05). Cachexia was associated with a higher toxicity manifested by diarrhoea (P = 0.02), nausea (P = 0.02), and anorexia (P < 0.01 and P = 0.03 at Cycles 1 and 2, respectively). Sarcopenic and cachetic individuals experienced more toxicities and DLT during chemotherapy. The only factors associated with DLT in the multivariate Cox regression analyses including the presence of metastasis and the chemotherapy protocol were cachexia and the ECOG scale (P < 0.001 for both). CONCLUSIONS: Cachexia and ECOG score may identify patients with an increased risk for developing severe toxicity events during chemotherapy treatment for gastrointestinal cancer.