Impact of maintenance therapy with fluoropyrimidines in advanced esophageal-gastric adenocarcinoma: a retrospective study in Mexican population.

Background: Gastric carcinoma ranks as one of the most prevalent gastrointestinal malignancies globally, with heterogeneous clinical-biological behavior significantly affecting prognosis and treatment outcomes. In advanced stages, systemic chemotherapy remains the cornerstone of treatment, but associated toxicities often limit their duration. Maintenance therapy with fluoropyrimidines has shown promise in improving survival and quality of life in colorectal and other cancers. However, its role in advanced gastric cancer, particularly in the Mexican population, remains underexplored. This study aimed to evaluate the survival benefit and toxicity profile of maintenance therapy with fluoropyrimidines in this population. Methods: This retrospective study analyzed data from 190 patients with metastatic adenocarcinoma of the esophago-gastric junction and stomach treated between 2018 and 2023 at the Oncology Hospital, National Medical Center Century XXI. Patients with at least stable disease after induction chemotherapy based on fluoropyrimidines and platinum salts or camptothecins were included. Maintenance therapy with fluoropyrimidines (capecitabine or 5-fluorouracil) was evaluated. Progression-free survival (PFS), overall survival (OS), and toxicity profiles were assessed. Survival estimates were generated using the Kaplan-Meier method, and multivariate analyses employed Cox proportional hazards models, with significance set at P<0.05. Results: The median follow-up was 17.4 months. Median PFS was 11.4 months [95% confidence interval (CI): 10.38-12.55], and median OS was 17.0 months (95% CI: 13.8-20.2). Patients with G1 tumors showed significantly longer PFS (22.8 months) compared to G3 tumors [10.8 months; hazard ratio (HR) =1.41, P<0.001]. Maintenance therapy with capecitabine was predominant (75.8%), with a median of six cycles administered. Common adverse events included neuropathy (52.6%), hand-foot syndrome (47.4%), and fatigue (43.7%). Grades 3-4 toxicities were rare, with hand-foot syndrome (7.4%) and fatigue (5.3%) being the most reported. Conclusions: Maintenance therapy with fluoropyrimidines demonstrates a favorable survival benefit and manageable toxicity profile in advanced esophago-gastric adenocarcinoma. Despite limitations, including the study's retrospective design and the absence of direct comparisons with non-maintenance groups, these findings align with international studies, suggesting that fluoropyrimidines offer an effective strategy to prolong the benefits of first-line treatment in gastric cancer. Further studies incorporating human epidermal growth factor receptor 2 (HER2) and immune checkpoint inhibitors are warranted to enhance therapeutic personalization.