690PCombination versus single-agent as palliative chemotherapy for gastric cancer: Significance of age and platelet-to-lymphocyte ratio

Background: Although combination chemotherapy (CC) is generally recommended in recurrent or metastatic gastric cancer, the results of randomized trials are conflicting. Methods: A retrospective review was conducted on 687 patients who received palliative chemotherapy for recurrent (n = 304) or primary metastatic (n = 383) gastric cancer. We compared the overall survival (OS) between CC and single-agent chemotherapy (SC) among these patients, while analyzing clinicopathological characteristics affecting outcome including neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). Results: While 521 (75.8%) patients underwent CC, SC was more frequently performed in old age (≥70) (57.6%) and ECOG performance status (PS) 2/ 3 (65.8%) patients (p < 0.0001, both). The median OS of patients who received CC was significantly longer than that of patients who received SC (11 vs. 8 months, p < 0.0001). Although patients with CC showed better OS in the majority of subgroups, no difference in OS between CC and SC was observed in patients with old age (p = 0.599), ECOG PS 2/3 (p = 0.821), signet ring cell histology (p = 0.40), palliative surgical resection (p = 0.407), and high PLR (P = 0.137), with a significant interaction between age and type of the regimen (CC vs. SC) (p = 0.011). Multivariate analysis revealed that palliative resection and ≥2nd line chemotherapy were independently associated with favorable OS (p < 0.0001, both), whereas ECOG PS 2/3 (p = 0.004), poorly differentiated and signet ring cell histology (p = 0.02, p < 0.0001), peritoneal metastasis (p = 0.045), high NLR (P = 0.001), and high PLR (P = 0.028) were independent prognostic factors of poor OS. In patients who underwent palliative resection before chemotherapy, there was a significant interaction between PLR and type of the regimen (p = 0.017), without significant difference in OS between CC and SC in patients with high PLR (p = 0.306). Conclusions: Although CC is the standard of care in recurrent or metastatic gastric cancer, SC can be considered as a reasonable option in certain subgroups, such as elderly patients or those with high PLR after palliative resection. Legal entity responsible for the study: Department of Hematology-Oncology, Ajou University School of Medicine. Funding: Samyang Biopharmaceuticals Corporation. Disclosure: All authors have declared no conflicts of interest.