e16588 Background: While gastric cancer is a leading cause of cancer-related mortality in Eastern Europe and Asia, it is less common in the United States. Recommendations regarding optimal treatment of non-metastatic gastric cancer (nmGC) with regard to type and extent of surgery, choice and sequence of chemotherapeutic agents, and use of radiation therapy vary somewhat depending on geographic location. To determine how variability in treatment practices affects patient outcomes, we conducted a retrospective study to evaluate clinical outcomes in nmGC patients treated at four high-volume academic institutions. Methods: California Cancer Registry of demographic and clinical data were collected for nmGC patients who underwent surgery with curative intent from 2010-2018. We conducted chart reviews of the patients’ electronic health records to validate clinical factors and outcomes. We performed multivariable Cox regressions to determine prognostic factors for outcomes. Results: Demographics of study cohort (n = 326): mean age 66 years; 64% male; 44% Caucasian, 35% Asian, 16% Latino. Tumor stage: 48% loco-regional (pT4 or pN1+) versus 52% localized (pT1-3, pN0). Histology: 47% intestinal, 30% diffuse, 8% mixed, 15% unknown. Surgery: number of recovered lymph nodes varied from 0 to 60 in any tumor stage. Chemotherapy: 20% neoadjuvant, 25% adjuvant, 16% perioperative, 39% none. Multimodality therapy: 44% surgery only, 31% chemotherapy, 25% chemotherapy and radiation. With a median follow-up after surgery of 6 years, 24% of patients developed recurrence and 40% had died. Compared to open surgery, laparoscopic surgeries was associated with lower lymph node recovery (median = 15 vs 19, p = .0042), which in turn was associated with a significant decrease in overall 5-year survival after adjusted for tumor stage (hazard ratio HR = 1.9, p = .0012). Timing of chemotherapy and addition of radiation therapy to chemotherapy did not confer further improvements in survival. In contrast, greater lymph node recovery plus chemotherapy were associated with improved survival in patients with loco-regional tumors (HR = 0.3, p = .0020). Conclusions: This study highlights major practice differences in the management of nmGC across providers and institutions. Further efforts should be made to standardize the use of chemotherapy and adequate recovery and assessment of lymph nodes in this patient population.
P-184 Survival patterns of positive lymph node non metastatic gastric cancer in the United States
