Background: Desmoid tumors, which are associated with familial adenomatous polyposis (FAP), tend to occur frequently in the abdominal wall and mesentery. Currently, there are no recognized treatments other than surgery, and frequent surgeries result in gastrointestinal obstructions and functional gastrointestinal disorders.
Case presentation: After surgery that was performed on a 39-year-old patient with FAP, we performed a second tumor excision which was the procedure used for frequently occurring mesenteric desmoid tumors. It was determined that the enlarged tumor would be difficult to operate on through an abdominal incision. Subsequently, the carbon ion radiotherapy of 50 Gy was then performed on the patient. Three years later, the tumor still remains reduced in size. In addition, we have not observed any negative effect on the digestive tract.
Conclusions: This is the first instance that the carbon ion radiotherapy has been effective for the unresected desmoid tumor, and it is believed that this will become the one effective option for the treatment of desmoid tumors.
Keywords: Carbon ion radiotherapy; Desmoid tumor; Mesenteric; Unresectable.