Loss of skeletal muscle mass during treatment is associated with reduced overall survival in gastric cancer patients undergoing conversion surgery

Background: The recent introduction of multimodal approach in the setting of conversion surgery (CS) significantly improved survival of stage IV gastric cancer (GC) patients. The prognosis has been related to several tumor and patient factors. Abnormal body composition, specifically the depletion of the lean mass compound, have been associated with impaired short- and long-term outcomes in GC. Aim was to analyze potential variation of body composition during systemic treatment and to evaluate aftermath on further resection and survival. Methods: In this retrospective monocenter analysis, we assessed pre-treatment and preoperative body composition of stage IV GC patients who underwent surgical exploration following systemic treatment in the setting of CS, over a 12-year period. A radiologist blinded to the patient outcomes assessed the areas of skeletal muscle, and adipose tissue by a dedicated software through standardized protocols. Demographics and clinical data were obtained from prospectively maintained databases and patient records. Results: We included 42 GC patients. Median age was 59 years, 27, 64.3 % were male, and 22/42 were Yoshida category 3 and 4. Surgical interventions included curative resection (23/42 cases), or palliation (19/42). We observed difference in the distribution of body components according to gender, at diagnosis, with more subcutaneous adipose tissue in males (p < 0.001) vs. more visceral adipose tissue in females (p = 0.039). During systemic treatment, a significant increase in total muscle area was observed, but nor in males (median delta TMA -7cm2 in males and delta TMA +4.8 cm2 in females, p = 0.048). Increased TMA during chemotherapy was associated with improved overall survival, with median OS 63 months, vs. 27 months for patients who lost lean mass (p = 0.042). The protective effect of increased TMA was also confirmed at a multivariate analysis after normalization for age and type of surgical procedure (HR 0.98, 95%CI 0.97–0.99; p = 0.035). Conclusion: As increased skeletal muscular mass during systemic treatment independently improved the overall survival, longitudinal evaluation of body composition must be part of routinary work-up of gastric cancer patients in the setting of conversion surgery. Potential effects of nutritional interventions must be evaluated.