EP 494 Can CT-Derived Skeletal Muscle Metrics Guide Treatment Decisions in Lavage Cytology–Positive Patients with Gastric Cancer Undergoing Conversion Therapy?
Ping’An Ding, Peigang Yang, Li Yang, Chenyu Sun, Shuya Chen, Qun ZhaoAbstract
Aims
To determine the impact of pre-treatment sarcopenia, newly developed sarcopenia after therapy, and significant muscle loss (SML) during conversion therapy on conversion success, tumour response, and survival in patients with GC-CY1.
Methods
Retrospective analysis of GC-CY1 patients from a prospective conversion therapy trial between Apr 2018 and Aug 2019. CT-derived skeletal muscle index (SMI) was measured at L3. Sarcopenia was defined using published cut-offs. Multivariable logistic regression assessed conversion success; Cox regression assessed overall survival (OS) and progression-free survival (PFS).
Results
36 patients were included. Sarcopenia prevalence was 19.4% pre-treatment; 16.7% developed new sarcopenia post-treatment; and 22.2% developed SML during therapy. On multivariable analysis, both pre-treatment sarcopenia and SML during therapy were associated with reduced conversion therapy success. Pre-treatment sarcopenia independently predicted worse OS (HR 6.341, 95%CI 1.269–18.943, p=0.001) and PFS (HR 8.212, 95%CI 1.569–36.582, p=0.001). Newly developed sarcopenia after conversion therapy predicted worse OS (HR 3.189, 95%CI 1.023–9.811, p=0.012) and PFS (HR 3.084, 95%CI 1.042–14.236, p=0.013). Presence of SML during therapy had the strongest association with poor outcomes (OS HR 10.234, 95%CI 2.532–54.231, p=0.002; PFS HR 9.562, 95%CI 2.341–38.092, p=0.002).
Conclusion
Pre-treatment sarcopenia and interval skeletal muscle loss during conversion therapy are strongly associated with reduced conversion success and markedly worse OS/PFS. CT may provide a pragmatic imaging biomarker to guide risk stratification during treatment.