Predictive value of pancreatic dose-volume metrics on sarcopenia rate in gastric cancer patients treated with adjuvant chemoradiotherapy.

OBJECTIVE: To evaluate the relationship of sarcopenia with the pancreatic dose-volume histogram (DVH) in gastric cancer patients treated with adjuvant chemoradiotherapy (CRT) after radical gastrectomy. METHODS: A retrospective study was performed on the data in Zhongnan Hospital of Wuhan University from January 2008 to December 2016. Skeletal muscle index (SMI) was analyzed by cross-sectional areas of body composition at the level of third lumbar (L3) vertebrae, which was measured using single-slice computer tomograph (CT) prior to CRT, at 6 months and 12 months after CRT respectively. Logistic regression analysis was conducted to explore the potential clinical risk factors of sarcopenia in this patients cohort. Regarding the dosimetrics of pancreas, the sarcopenia rate was compared between the two groups divided according to the cut-off value determined by the receiver operating characteristic (ROC) curves. RESULTS: One hundred and fifty-three gastric cancer patients were eligible in this study. The median postoperative follow-up was 36 (7-115) months. The mean dose of pancreas was 4399.7 ± 396.0 cGy. The incidence of sarcopenia prior to CRT, at 6 months and 12 months later were 29.4% (45/153), 27.3% (35/128) and 37.0% (37/100). Both sarcopenia at 6 months (HR = 2.038, 95%CI = 1.084-3.833, P = 0.027) and sarcopenia at 12 months (HR = 2.216, 95%CI = 1.007-4.873, P = 0.048) were the independent prognostic factor of gastric cancer patients. V46 remained to be the only independent risk factor of sarcopenia at 6 months (OR = 3.889, 95%CI = 1.099-13.764, P = 0.035) and 12 months (OR = 6.067, 95%CI = 1.687-21.821, P = 0.006) in multivariate logistic regression analysis. Among the dosimetric parameters used for ROC analysis, the V46 showed the highest area under the curve (AUC = 0.707). Here is the relationship between sarcopenia rate and the cut-off value for V46. Higher sarcopenia rate at 6 months was noted in 42.6% patients with V46 ≥ 57% compared with 9% of patients with V46 < 57% (P < 0.001). The sarcopneia rate at 12 months was 52% with V46 ≥ 57% and 25% with V46 < 57% (P = 0.010). CONCLUSION: Gastric cancer with sarcopenia after adjuvant CRT had poorer survival. Higher dose and larger irradiated volume of pancreas correlated with higher risk of sarcopenia. Appropriated administration of pancreas dose-volume may be conducive to reduce the risk of sarcopenia and improve survival in gastric cancer patients treated with adjuvant CRT.