Definitive high-dose photon/proton radiotherapy for unresected mobile spine and sacral chordomas.

STUDY

DESIGN

A retrospective review.

OBJECTIVE

The purpose of this study is to report the results of high-dose proton based definitive radiotherapy for unresected spinal chordomas.

SUMMARY OF BACKGROUND DATA: Spine chordoma is treated primarily by surgical resection. However, local recurrence rate is high. Adjuvant radiotherapy improves local control. In certain locations, such as high sacrum, resection may result in significant neurological dysfunction.

METHODS

We retrospectively reviewed 24 patients with newly diagnosed, previously untreated spinal chordomas (core biopsy only; no prior incision or resection) treated with high-dose definitive radiotherapy alone using protons and photons at our center from 1988 to 2009.

RESULTS

Reasons for radiotherapy alone included medical inoperability (3) and concern for neurological dysfunction based on spine level (21). Median age was 69.5 years. Tumor locations included cervical (2), thoracic (1), lumbar (2), S1-S2 (17), and S3 or below (2). Median maximal tumor diameter was 6.6 cm (1.4-25.5), and median tumor volume was 198.3 cm (4.65-2061). Median total dose was 77.4 GyRBE (proton dose unit, gray relative biological effectiveness). Analysis at median follow-up of 56 months showed overall survival of 91.7% and 78.1%, chordoma specific survival of 95.7% and 81.5%, local progression free survival of 90.4% and 79.8% and metastases free survival of 86.5% and 76.3%, at 3 and 5 years respectively. Tumor volume more than 500 cm was correlated with worse overall survival. Long-term side effects included 8 sacral insufficiency fractures (none required surgical stabilization), 1 secondary malignancy, 1 foot drop, 1 erectile dysfunction, 1 perineal numbness, 2 worsening urinary/fecal incontinence, and 4 grade-2 rectal bleeding. None required new colostomy. All surviving patients remained ambulatory.

CONCLUSION

These results support the use of high-dose definitive radiotherapy for patients with medically inoperable or otherwise unresected, mobile spine or sacrococcygeal chordomas.