Pelvic insufficiency fractures after preoperative radiotherapy for rectal carcinoma

Insufficiency fractures of the pelvic bones are rare complications of radiotherapy, but they can cause significant morbidity. We report a patient who developed pelvic insufficiency fractures because of preoperative hypofractionated radiotherapy with chemotherapy for rectal carcinoma. She was treated with a four-field box technique, receiving 20 Gy in four fractions, and she underwent concurrent pharmacokinetic modulating chemotherapy (PMC; intravenous infusion of 5-fluorouracil [FU], 750 mg/body per 24 h and oral administration of uracil and futrafur [UFT] 400 mg/day) over a 1-week period. She developed severe buttock and femoral pain 10 months after this preoperative therapy. Physical examination at this time was unremarkable, with an absence of neurological signs, and radiographic examination was also normal, resulting in the patient initially being undiagnosed. However, 2 months after the onset of her initial pain, she was diagnosed as having pelvic insufficiency fractures on conventional radiographs. Although preoperative chemoradiotherapy has been widely accepted for improving local control and survival in patients with primary rectal carcinoma, surgeons need to be aware of this rare complication that can arise even 10 months after preoperative chemoradiotherapy.