The prevalence of CT-defined low skeletal muscle mass in patients with metastatic cancer: a cross-sectional multicenter French study (the SCAN study)

Background Cachexia, characterized by involuntary muscle mass loss, negatively impacts survival outcomes, treatment tolerability, and functionality in cancer patients. However, there is a limited appreciation of the true prevalence of low muscle mass due to inconsistent diagnostic methods and limited oncologist awareness. Methods Twenty-nine French healthcare establishments participated in this cross-sectional study, recruiting patients with those metastatic cancers most frequently encountered in routine practice (colon, breast, kidney, lung, prostate). The primary outcome was low skeletal muscle mass prevalence, as diagnosed by estimating the skeletal mass index (SMI) in the middle of the third-lumbar vertebrae (L3) level via computed tomography (CT). Other objectives included an evaluation of nutritional management, physical activity, and toxicities related to ongoing treatment. Results Seven hundred sixty-six patients (49.9% males) were enrolled with a mean age of 65.0 years. Low muscle mass prevalence was 69.1%. Only one-third of patients with low skeletal muscle mass were receiving nutritional counselling and only 28.4% were under nutritional management (oral supplements, enteral or parenteral nutrition). Physicians highly underdiagnosed those patients identified with low skeletal muscle mass, as defined by the primary objective, by 74.3% and 44.9% in obese and non-obese patients, respectively. Multivariate analyses revealed a lower risk of low skeletal muscle mass for females (OR: 0.22, P 0.01) and those without brain metastasis (OR: 0.34, P 0.01). Low skeletal muscle mass patients were more likely to have delayed treatment administration due to toxicity (11.9% versus 6.8%, P = 0.04). Conclusions There is a critical need to raise awareness of low skeletal muscle mass diagnosis among oncologists, and for improvements in nutritional management and physical therapies of cancer patients to curb potential cachexia. This calls for cross-disciplinary collaborations among oncologists, nutritionists, physiotherapists, and radiologists.