Liver surgery involves removing portions of the liver to treat various disorders like malignant tumors, which are either primary tumors in the liver or metastases from other organs like the colon. Common procedures include resection of liver tumors as well as surgery for conditions like portal hypertension. Specialized liver surgeons at centers like Dr. Dmitri Alden in New York perform various types of liver and bile duct surgeries to treat hepatocellular carcinoma, liver metastases, benign liver tumors, and cholangiocarcinoma.