Laparoscopic Ultrasound (LUS) is an important part of the pre-treatment evaluation of patients with upper gastrointestinal tract cancer (esophageal, gastric, pancreatic and liver cancer). When a suspect lesion is visualized during LUS a biopsy should be provided in order to differentiate between benign and malignant lesions. A new system for LUS guided biopsy has been developed, but how often these biopsies are clinically relevant (i.e. changing patient management)and how reliable are these biopsies are unknown. The study hypothesis is that LUS guided biopsies are accurate and clinically relevant in the pre-treatment evaluation of patients with upper gastrointestinal tract cancer.