Real-world experience with first-line pembrolizumab plus chemotherapy in Vietnamese patients with stage IV esophageal squamous cell carcinoma

Introduction Esophageal squamous cell carcinoma (ESCC) remains a major cause of cancer-related mortality in Asia. Pembrolizumab in combination with chemotherapy has become a standard first-line option based on phase III trial data, but real-world evidence from Vietnam is lacking. This study examined the clinical characteristics, disease course, and treatment-related toxicities of Vietnamese patients with stage IV ESCC receiving this regimen. Methods We conducted a single-center, single-arm, retrospective analysis of 53 patients with stage IV ESCC treated with pembrolizumab plus platinum- and fluoropyrimidine-based chemotherapy. Information on demographics, clinical presentation, pathology, biomarker status, treatment regimens, patterns of progression or recurrence, and adverse events (AEs) was collected from electronic health records. Results The mean age was 59 years, with nearly all patients being male. Most presented with advanced T3/N2 disease and dysphagia at diagnosis. PD-L1 status was unavailable in about one-third of cases. Common chemotherapy backbones were CF (50.9%) and XELOX/SOX (24.5%). Progression or recurrence was documented in 24.5% of patients, and 20.8% occurred within six months. Lymph nodes were the most frequent site of progression, followed by local and distant recurrence. Hematologic toxicities were common, including neutropenia (43.4% all grades, 13.2% grade ≥3) and anemia (50.9% all grades). Nausea (20.8%) and diarrhea (5.7%) were the main gastrointestinal toxicities. Immune-related events included hypothyroidism (3.8%) and pneumonitis (3.8%). Conclusions In this Vietnamese cohort, pembrolizumab plus chemotherapy showed a manageable safety profile and recurrence patterns consistent with those reported internationally. These findings add region-specific real-world evidence and underline the importance of broader multi-center studies with longer follow-up to inform practice in advanced ESCC.