Low dose radiotherapy is associated with local complications but not disease control in sacral chordoma

Background: We reviewed the disease control and complications of the treatment of sacrococcygeal chordoma from four tertiary cancer centers with emphasis on the effects of radiotherapy in surgically treated patients. Methods: A total of 193 patients with primary sacrococcygeal chordoma from 1990 to 2015 were reviewed. There were 124 males, with a mean age of 59 ± 15 years and a mean follow-up of 7 ± 4 years. Eighty-nine patients received radiotherapy with a mean total dose of 61.8 ± 10.9 Gy. Results: The 10-year disease-free and disease-specific survival was 58% and 72%, respectively. Radiation was not associated with local recurrence (hazard ratio [HR], 1.13; 95% confidence interval [CI], 0.59-2.17; P = 0.71), metastases (HR, 0.93; 95% CI, 0.45-1.91; P = 0.85) or disease-specific survival (HR, 0.96; 95% CI, 0.46-2.00; P = 0.91). Higher doses (≥70 Gy; HR, 0.52; 95% CI, 0.20-1.32; P = 0.17) may be associated with reduced local recurrence. Radiotherapy was associated with wound complications (HR, 2.76; 95% CI, 1.64-4.82;, P < 0.001) and sacral stress fractures (HR, 4.73; 95% CI, 1.88-14.38; P < 0.001). Conclusions: In this multicenter review, radiotherapy was not associated with tumor outcome but associated with complications. The routine use of radiotherapy with en-bloc resection of sacrococcygeal chordomas should be reconsidered in favor of a selective, individualized approach with a radiation dose of ≥70 Gy.