Enhancing evaluation of sarcopenia in patients with non-small cell lung cancer (NSCLC) by assessing skeletal muscle index (SMI) at the first lumbar (L1) level on routine chest computed tomography (CT)

Ongoing cancer cachexia trials evaluate sarcopenia by skeletal muscle index (SMI) at the L3 vertebrae level, commonly used as a standard. Routine chest CT institutional protocols widely differ in including L3. We investigated whether SMI at L1 assessment, rather than L3, would be reliable and more practicable for non-small cell lung cancer (NSCLC). NSCLC patients with routine CT chest had SMI measurements performed at L1 using Slice-O-Matic software. Accuracy of including L1 level, imaging quality, and ability to detect sarcopenia was collected and correlation of L1 SMI with body mass index (BMI) was performed. Thirty-seven patients with NSCLC (73 CT assessments) were enlisted at three institutions. Characteristics: 47% female; medians: age 59, KPS 80%; BMI 25.49, weight 72.97 kg, SMI 59.24. Sarcopenia was detected in 14.7% of patients; 20% had sarcopenic obesity. Of the 73 CTs, 94.5% included L1 (95% CI 86.6-98.5%). Three images (4%) were difficult to evaluate. Inclusion of L1 was similar among the three participating institutions (90.4 to 96.7% inclusion). BMI correlation with SMI was weak (r = 0.329). SMI assessment at L1 is achievable in patients with NSCLC receiving routine chest CT, with 96% having acceptable quality evaluations. Similar to results previously reported at L3, BMI showed poor correlation and low sensitivity to detect muscle mass loss. The use of CT at L1 is reliable and presents the opportunity for easier patient evaluation of sarcopenia in patients with lung cancer without the need for additional testing or radiation exposure.