BACKGROUND:Gastrointestinal cancers,especially pancreatobiliary cancers,are frequently associated with or are complicated by thromboembolic phenomena due to hypercoagulability and/or altered venous drainage,especially of the abdomen and lower limbs.This report describes an unusual and interesting case of gallbladder carcinoma developing a viable tumor thrombus in the superior vena cava(SVC)with resultant SVC obstruction,while on gefitinibbased anti-epidermal growth factor receptor(EGFR)therapy.METHODS:A 60-year-old woman was incidentally diagnosed to have gallbladder cancer on cholecystectomy.She had disease recurrence and received systemic chemotherapy followed by gefitinib-based anti-EGFR therapy.Subsequently,while on gefitinib-based therapy,she presented with clinical signs and symptoms suggestive of SVC thrombosis.RESULTS:A whole body PET scan revealed a metabolically active tumor thrombus in the SVC,besides other sites of metabolically active disease inclusive of the lung parenchyma, lymph nodes and abdomen.She was treated with antithrombotics and external beam radiotherapy directed to the SVC thrombus leading to symptomatic relief.She continues to survive on the day of writing this report.CONCLUSIONS:This rare complication,though theoretically possible,is unreported because of the short overall survival of advanced gallbladder cancer patients.This highlights that with the availability of better chemotherapeutic/biotherapeutic agents for increasing in the lifespan of cancer patients,we may come across such cases more frequently in the future. BACKGROUND: Gastrointestinal cancers, particularly pancreatobiliary cancers, are frequently associated with or are complicated by thromboembolic phenomena due to hypercoagulability and / or altered venous drainage, especially of the abdomen and lower limbs. This report describes an unusual and interesting case of gallbladder carcinoma developing a viable tumor thrombus in the superior vena cava (SVC) with resultant SVC obstruction, while on gefitinibbased anti-epidermal growth factor receptor (EGFR) therapy. METHODS: A 60-year-old woman was incidentally diagnosed to have gallbladder cancer on cholecystectomy. had disease recurrence and received systemic chemotherapy followed by gefitinib-based anti-EGFR therapy. However, while on gefitinib-based therapy, she presented with clinical signs and symptoms suggestive of SVC thrombosis. RESULTS: A whole body PET scan revealed a metabolically active tumor thrombus in the SVC, besides other sites of metabolically active disease inclusive of the lung parenchy ma, lymph nodes and abdomen. he was treated with antithrombotics and external beam radiotherapy directed to the SVC thrombus leading to symptomatic relief. he continues to survive on the day of writing this report.CONCLUSIONS: This rare complication, though theoretically possible possible, is unreported because of the short overall survival of advanced gallbladder cancer patients. this highlights that with the availability of better chemotherapeutic / biotherapeutic agents for increasing in the lifespan of cancer patients, we may come across such cases more frequently in the future.