Exploring the Relationship between CT Determined Skeletal Muscle Mass and Physical Functional Limitation in Lung Cancer Patients: A Gender-Based Analysis

Abstract

Background: Low skeletal muscle mass is a prevalent issue in lung cancer patients, with potential implications linked to poor prognosis, treatment toxicity, impaired physical functions and reduced survival. Despite previous reports on the associations between low skeletal muscle mass and physical functions, conflicting results have been reported in the literature. The relationship between skeletal muscle mass and physical function in cancer patients is complex depending on various factors such as age, gender, co morbidities and treatment received. The influence of gender differences on muscle mass and its impact on physical function is not clearly understood. Objective: To explore gender differences in skeletal muscle mass measured using CT-defined 3rd lumbar vertebra skeletal muscle index(L3SMI) and its association to physical functional limitation measured using short physical performance battery test (SPPB) in lung cancer patients. Material and methods: A cross-sectional study of 172 lung cancer patients. 59.9 % of patients were enrolled before treatment, 27.9 % during treatment and 12.2 % during surveillance after treatment. Skeletal muscle index (SMI) was assessed utilizing CT determined skeletal muscle area (SMA) at the 3rd lumbar vertebra. The SPPB score was used to assess physical functions and physical functional limitation was defined as a score less than or equal to 9. SMI, age and gender impact on physical limitation was assessed using logistic regression. Results: The study included 95 females and 77 males with a mean(SD) age of 66 (9.7) years. Females had a lower mean(SD) weight of 53 (10.4) kg and a slightly higher mean(SD) BMI of 23 (4.1) as compared to males. The logistic regression analysis revealed that SMI was significantly associated with the outcome of PFL in lung cancer patients (OR = 0.96, 95% CI: 0.91-1.00, p = 0.034). However, the inclusion of gender as a predictor did not show a significant impact on the outcome (OR = 0.50, 95% CI: 0.21-1.15, p = 0.11). Age, on the other hand, emerged as a significant predictor of the outcome (OR = 1.14, 95% CI: 1.09-1.21, p < 0.001), with each year increase in age associated with 14% higher odds of experiencing physical functional limitation. The best-fitting model, based on AIC and BIC values, included SMI, gender, and age as predictors. The AIC and BIC values for this model were 165.43 and 178.02, respectively. In comparison when SMI was included as the only predictor, it showed higher AIC (199.21) and BIC (205.50) values. Conclusion: Increasing age and decreasing skeletal muscle mass were associated with a higher likelihood of experiencing physical functional limitations. Gender, however, did not significantly affect the relationship between skeletal muscle mass and functional limitations. Instead, the combined effect of sex, age, and skeletal muscle mass was found to be important in determining the likelihood of individuals facing physical functional limitations.