P1.230. Rare Esophageal Cancers in Finland: A 30-Year Nationwide Registry Study

Abstract

Abstract Topic Esophageal Cancer: Surgical Treatment of Esophageal Cancer – long term outcomes Background Esophageal cancers other than adenocarcinoma and squamous cell carcinoma are rare and not well characterized. Most evidence published are case reports or small institutional series. We conducted the first nationwide study of rare esophageal cancers to determine their incidence, histological distribution, and survival outcomes. Methods This retrospective, population-based registry study identified all adult patients diagnosed with rare esophageal and gastric cardia cancers (ICD-10: C15.X, C16.0) excluding adenocarcinoma and squamous cell carcinoma in Finland from 1987–2018. Data were obtained from the Finnish Cancer Registry, Cause of Death Registry, and Care Register for Health Care. Cases with undifferentiated or unspecified carcinoma histology were excluded. Primary outcome was overall survival. Prognostic variables included age, sex, histological type, and treatment modality. Survival was estimated using Kaplan-Meier methods and compared with log-rank tests. Poisson regression assessed temporal incidence trends. Results Among 1,497 esophageal cancers other than adenocarcinoma and squamous cell carcinoma identified, 157 patients with specified rare histologies were included after excluding 1,340 undifferentiated/unspecified cases. Mean age was 70.2 years; 62.4% were male. Histological distribution of the cancers was neuroendocrine carcinoma 54.1% (n=85), sarcoma 12.7% (n=20), adenosquamous carcinoma 12.1% (n=19), GIST 9.6% (n=15), melanoma 5.1% (n=8), other 6.4% (n=10). Annual incidence increased significantly over the study period (incidence rate ratio 1.08 per year, 95% CI 1.05–1.10, p=0.001). Esophagectomy was performed in 17.3% of patients. Median overall survival was 6.5 months. Survival differed significantly by histological subtype (p=0.001). Surgical management was associated with significantly prolonged survival compared to non-surgical treatment (p=0.001). Conclusion This first population-based study demonstrates rising incidence of rare esophageal cancers in Finland, with neuroendocrine carcinoma being the most common subtype. Overall prognosis remains poor, though outcomes vary by histological type. Surgery appears associated with improved survival in selected patients. The large proportion of undifferentiated/unspecified cases suggests diagnostic challenges and potential underestimation of true incidence.