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Tumors of the intestinal epithelial lining include non-cancerous polyps, benign adenomas and malignant epithelial tumors (adenocarcinomas). The polyps and adenomas may be multiple and cause local obstruction. The malignant tumors cause progressive illness and often spread (metastasize) before clinical diagnosis. Secondary tumors are found in the lymph nodes (glands), on the inside lining of the abdomen (peritoneum) and in the liver and lungs. Survival time with malignant intestinal tumors is often only months, although it is longer if the tumor has not spread before surgery.