Near-complete pathological response of chordoma to high-dose single-fraction radiotherapy: case report.
High-dose, single-fraction radiotherapy, also known as radiosurgery, has theoretical advantages for the treatment of chordoma, which is considered resistant to conventional radiation therapy. Demonstration of biological effectiveness, as indicated by pathological response of a chordoma specimen after such radiotherapy, has not previously been reported. A 72-year-old man presented with lower back pain and was found to have an L3 vertebral mass. Open biopsy yielded chordoma. He was considered for en bloc resection, but definitive radiation therapy was preferred owing to medical comorbidities and concern for field contamination from the previous biopsy. The patient underwent single-fraction, high-dose, image-guided radiation therapy to the tumor. Two months later, he underwent kyphoplasty because of recurrent pain. A core biopsy performed at that time showed viable chordoma. Four months after treatment, he underwent L3 corpectomy because of symptoms of mechanical instability. Pathology now showed near-complete necrosis of the resected chordoma. Preoperative, single-fraction radiotherapy for chordoma induced a near-complete pathological response in this patient. That the effect was seen at 4 months but not 2 months after treatment suggests a time-dependent effect. This case suggests a promising role for single-fraction, image-guided radiation therapy in the treatment of chordoma.