Pancreato-Hepatobiliary Malignancies: A Comprehensive Narrative Review of Epidemiology, Diagnosis, Multimodal Management, the Evolving Systemic Therapy Landscape, and Survival - Sophia Tsokkou; Menelaos Papakonstantinou; Paraskevi Chatzikomnitsa; Areti Danai Gkaitatzi; Evdokia Toutziari; Dimitrios Giakoustidis; Vasileios N. Papadopoulos; Alexandros Giakoustidis (Gastroenterology Insights, 2026)