[A Case of Rectal Cancer with Multiple Endocrine Neoplasia Type 2]

A 63-year-old man with multiple endocrine neoplasia type 2(MEN2)was admitted to the hospital because of positive fecal occult blood tests. Colonoscopy revealed a 50mm type 2 tumor at the rectum, which was diagnosed as an adenocarcinoma based on histology. Since there was no apparent distant metastasis, laparoscopy-assisted low anterior resection with regional lymph node dissection was performed. The final diagnosis was pT3, pN0, pM0, pStage II . Almost all patients with MEN2 have RET mutations, and they are resistant to EGFR inhibitors. Those who have thyroid cancer with RET mutations are often given a RET kinase inhibitor. In this case, if the patient develops recurrent rectal cancer, it warrants checking for RET mutations and using a multi-kinase inhibitor.