Is there a preferred platinum and fluoropyrimidine regimen for advanced HER2-negative esophagogastric adenocarcinoma? Insights from 1293 patients in AGAMENON–SEOM registry

Background The optimal chemotherapy backbone for HER2-negative advanced esophagogastric cancer, either in combination with targeted therapies or as a comparator in clinical trials, is uncertain. The subtle yet crucial differences in platinum-based regimens' safety and synergy with combination treatments need consideration. Methods We analyzed cases from the AGAMENON–SEOM Spanish registry of HER2-negative advanced esophagogastric adenocarcinoma treated with platinum and fluoropyrimidine from 2008 to 2021. This study focused exclusively on patients receiving one of the four regimens: FOLFOX (5-FU and oxaliplatin), CAPOX (capecitabine and oxaliplatin), CP (capecitabine and cisplatin) and FP (5-FU and cisplatin). The aim was to determine the most effective and tolerable platinum and fluoropyrimidine-based chemotherapy regimen and to identify any prognostic factors. Results Among 1293 patients, 36% received either FOLFOX ( n = 468) or CAPOX ( n = 466), 20% CP ( n = 252), and 8% FP ( n = 107). FOLFOX significantly increased PFS (progression free survival) compared to CP, with a hazard ratio of 0.73 (95% CI 0.58–0.92, p = 0.009). The duration of treatment was similar across all groups. Survival outcomes among regimens were similar, but analysis revealed worse ECOG–PS (Eastern Cooperative Oncology Group–Performance Status), > 2 metastatic sites, bone metastases, hypoalbuminemia, higher NLR (neutrophil-to-lymphocyte ratio), and CP regimen as predictors of poor PFS. Fatigue was common in all treatments, with the highest incidence in FOLFOX (77%), followed by FP (72%), CAPOX (68%), and CP (60%). Other notable toxicities included neuropathy (FOLFOX 69%, CAPOX 62%), neutropenia (FOLFOX 52%, FP 55%), hand–foot syndrome in CP (46%), and thromboembolic events (FP 12%, CP 11%). Conclusions FOLFOX shown better PFS than CP. Adverse effects varied: neuropathy was more common with oxaliplatin, while thromboembolism was more frequent with cisplatin.