Abdominal Neoplasms

The goal of this clinical trial is to determine whether Neurolytic Splanchnic Nerve Block (NSNB) reduces pain in adults with upper abdominal malignancies. It will also evaluate the safety of Neurolytic Splanchnic Nerve Block (NSNB). The main questions it aims to answer are: Does NSNB reduce pain intensity compared to Neurolytic Coeliac Plexus Block (NCPB), as measured by the Visual Analog Scale (VAS)? What adverse effects do participants experience when receiving Neurolytic Splanchnic Nerve Block (NSNB)? Investigators will compare Neurolytic Splanchnic Nerve Block (NSNB) with Neurolytic Coeliac Plexus Block (NCPB) to determine which intervention provides more effective and safer pain relief. Participants will: * receive either NSNB or NCPB under fluoroscopic guidance * be monitored immediately and for 2 hours after the procedure for any complications Have their pain intensity recorded immediately after the procedure, and at 7 days, 1 month, and 3 months * be evaluated for quality-of-life using European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire - Core 3 (EORTC QLQ-C30) at 1 month and 3 months. * have their opioid consumption tracked throughout the study.