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Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Abstract: Polypoid epithelial tumors of the duodenum and ampulla of Vater are rarely diagnosed preoperatively without wide application of fiberoptic endoscopy. The symptoms are nonspecific. Only a high index of suspicion will lead to early diagnosis. Life-threatening complications and increased incidence of malignant transformations are associated with delayed diagnosis. This paper reviews 11 patients (nine previously unreported) with villous tumor of the ampulla of Vater and two with this neoplasm in the duodenum. It also reviews the important principles of management illustrated by the behavior of the tumors of these 11 patients compared to those of previous reports. For favorable results, all lesions must be excised in toto and evidence of invasive malignancy must lead to aggressive treatment whenever feasible.
Output:
Villous tumors of the duodenum and ampulla of Vater.