Prognosis of gastric cancer (GC) patients with positive peritoneal cytology

41 Background: Laparoscopic staging of patients with GC can disclose peritoneal metastases. Although this finding is associated with a poor prognosis, some patients achieve a long-term survival. In an attempt to provide explanation we compared the overall survival (OS) of patients with GC peritoneal metastases from two settings: cytology positive only (Cy+) and grossly positive (Gross+). Methods: 146 GC patients with peritoneal metastases were identified between 2000 and 2014. Cox-model regression was used for overall survival (OS) analyses. Results: Patient/treatment characteristics were as follows: males (66%), good ECOG scores (0-1; 89%), metastases confirmed by a diagnostic laparoscopy (84%), poorly differentiated histology(92%), received chemotherapy (89%), received chemoradiation (22%), and received surgery (10%). The median follow-up time for all patients was 12.9 months and median OS was 15 months. Patients with Gross+ were at higher risk of death compared to Cy+ patients (50% vs. 83%1-year OS, respectively). Only diagnostic laparoscopy and metastasis type (Gross+ vs. Cy+) were significant in both univariate and multivariate OS models. With both factors in the same model, patients with Gross+ were more than twice as likely to die when compared to those with Cy+ (HR=2.23; p=0.001) while patients having a diagnostic laparoscopy were half as likely to die (HR=0.52; p=0.01). Conclusions: The one-year OS of patients with Cy+ peritoneal metastases is significantly longer than those with Gross+ findings. As such, novel strategies for Cy+ patients may further prolong their survival. From U. T. M. D. Anderson Cancer Center (UTMDACC), Houston, Texas, USA. (Supported in part by UTMDACC, and CA 138671 and CA172741 from the NCI).