In this paper, we discuss a 62-year-old woman who, in the course of 7 years (1994-2001), developed three cancers: adenocarcinoma of the stomach, adenocarcinoma of the cecum, and insular thyroid carcinoma, which metastasized to the retroperitoneal lymph nodes and liver. The patient died from complications related to the metastases. The results of basic genetic tests were normal. To the best of our knowledge, no other patient with the combination of these three cancers has been reported in the literature. Although patients with multiple cancers are not common, it is nonetheless important for clinicians to consider the possibility of second and third cancers in patients who were treated for a primary malignant tumor.