Gastrointestinal Cancer

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SU_18_2181 - Sarcopenia in Overweight or Obese patient is an adverse prognostic factor in Pancreatic Cancer.

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Sarcopenia in Overweight or Obese patient is an adverse prognostic factor in Pancreatic Cancer.
C. R. Nwachukwu, Y. Wu, D. A. S. Toesca, R. Von Eyben, E. Pollom, and D. T. Chang; Department of Radiation Oncology, Stanford Cancer Institute, Stanford, CA

Purpose/Objective(s): Sarcopenia is associated with poor outcomes in pancreatic cancer (PC) patients undergoing surgical resection, however there is limited data regarding the predictive value of sarcopenia in PC patients undergoing stereotactic body radiation therapy (SBRT). The purpose of this study is to evaluate if muscle composition and body weight, more specifically, sarcopenia, is of prognostic value in patients’ PC undergoing SBRT treatment.

Materials/Methods: We retrospectively extracted clinical data including BMI and reviewed the simulations CT scan of 200 PC patients who were treated with SBRT for unresectable disease between 2001 and 2015 at our institution. Sarcopenia was assessed on an axial CT slice at the level of the L3 vertebral body by measuring the total psoas area (TPA) and total muscle area (TMA) used as surrogates of whole body muscle composition. All values were normalized by individual patient height in m2 to obtain total psoas index (TPI) and total muscle index (TMI). The abdominal fat distribution was assessed at the same CT slice level by measuring visceral fat area (VFA) and subcutaneous fat area (SFA). Patient with BMI > 25 were considered overweight/obese. Contours were automatically generated using predefined ranges of Hounsfield Units (HU) for muscle density (30-110 HU) and fat density [(-150) - (-30)], using a commercially available deformable registration algorithm. Cut off for sarcopenia and increased fat content were based on previously published values. Overall survival (OS) was estimated by the Kaplan-Meier method.

Results: The median age at diagnosis was 68. 147 (75%) patients were sarcopenic, 91 patients were overweight/obese (45.7%) and 64 patients (32.6%) were both. Sarcopenic patients were much older than non-sarcopenic patients (p=0.003). Sarcopenia alone does not correlate with survival, but sarcopenic and obese patients have worse OS compared to sarcopenic non-obese patients (p=0.01). There was no correlation between OS and VFA. However, patients with low VFA/SFA ratio had significantly better OS than those with high VFA/SFA group (p=0.003). Male gender, chemotherapy, and albumin were identified as independent predictors of worse survival on multivariate analysis. Similar trends were observed in male patients with worse survival in the obese and sarcopenic patients compared to non-obese patients (p=0.03), but not in female patients. In addition, both male and female patients with low ratio VFA/SFA had significantly improved survival (p=0.005 and 0.04, respectively).

Conclusion: The prevalence of sarcopenia, which can be identified on CT scan by measuring TMA, in PC patients undergoing SBRT is high (75%). Sarcopenia is associated with worse overall survival only in obese patients. Further investigation is needed to determine the relationship between muscle content fat content and other known prognostic factors.

Author Disclosure: C.R. Nwachukwu: None. Y. Wu: None. D.A. Toesca: None. R. Von Eyben: None. E. Pollom: None. D.T. Chang: Research Grant; Varian Medical Systems. Stock; ViewRay.

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