Skeletal muscle area at the third lumbar vertebra on a routine CT correlates closely with whole-body muscle mass. Many radiology systems can measure it in minutes, and it can be normalised to height to give a skeletal muscle index. Low values identify patients at higher risk of chemotherapy toxicity, surgical complications and death, independent of body weight. Weight and BMI often miss sarcopenia, especially in people with obesity or fluid retention.
- Request an L3 skeletal muscle assessment on staging CT where your centre can provide it.
- Do not rely on BMI to judge muscle mass.
- Use low muscle mass to prompt dietitian review and activity advice.
- Consider it when weighing treatment intensity and toxicity risk.
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