Radiotherapy does not reduce mortality, local recurrence in resected sacral chordoma

WAILEA, Hawaii — Preoperative radiotherapy did not reduce risk for mortality, local tumor recurrence or metastasis among patients who underwent surgical treatment for sacral chordoma, according to study results presented at Connective Tissue Oncology Society Annual Meeting.

“However, preoperative radiotherapy was associated with a significantly increased risk for wound complications and sacral stress fractures,” Matthew T. Houdek, MD, orthopedic surgeon at Mayo Clinic in Rochester, Minnesota, said during a presentation.

Tumor size and the ability to achieve a negative margin appeared more predictive than other factors for local recurrence and mortality, Houdek added.

Sacrococcygeal chordomas are relatively resistant to chemotherapy.

En bloc excision with negative margins is standard treatment for sacrococcygeal chordomas. However, this approach often results in significant morbidity.

Recurrence is the most important factor in survival; however, the rate of local recurrence after complete surgical resection remains high. Consequently, some institutions use preoperative radiotherapy to try to reduce local recurrence risk, according to study background.

Houdek and colleagues conducted a retrospective multicenter study of patients treated at four large tertiary sarcoma centers in the United States and Canada to determine whether the addition of preoperative radiotherapy improved outcomes for patients with chordoma.

Key endpoints included OS, RFS, postoperative complications, and factors — such as the addition of radiotherapy to the treatment protocol — that affected treatment outcomes.

The researchers used a prospectively collected database to identify 235 patients (mean age, 59 years; range, 13-87; 64.6% men) who underwent curative-intent surgical resection of a primary sacrococcygeal chordoma at one of the four institutions between 1990 to 2015. Two of the centers routinely used radiotherapy as part of treatment, and the other two centers typically did not perform radiotherapy.

Surgeons obtained negative margins for 203 patients (86%), and the most frequent cephalad resection level was S2 (n = 75), researchers wrote.

Slightly more than half of the cohort (n = 125; 54%) received radiotherapy (mean dose, 55 Gy; range, 12-97). Of these, 54 received radiotherapy preoperatively and postoperatively, 51 received preoperative radiotherapy only, and 20 received postoperative radiotherapy only. Sixty-nine patients (29%) received proton therapy.

Researchers reported no significant differences between patients who received radiotherapy and those who did not with regard to age, sex, mean tumor volume, proportion of high sacral resections and proportion of positive margins.

Mean time to death was 4 years (range, 0 days to 14 years). Mean follow-up for surviving patients was 6 years (range, 1-25).

Forty patients died due to disease.

Researchers reported OS rates of 92% at 2 years, 83% at 5 years, and 71% at 10 years.

Radiotherapy did not appear associated with improved OS (HR = 1.53; 95% CI, 0.82-2.88).

Houdek and colleagues identified two factors associated with increased mortality: local recurrence (HR = 3.58; P < .001) and tumor size 9 cm or greater (HR = 2.22; P = .01).

Forty patients (17%) developed local recurrence, with a mean time to recurrence of 4 years (range, 3 months to 12 years).

Researchers reported local RFS rates of 93% at 2 years, 80% at 5 years and 74% at 10 years.

Positive margin increased risk for local recurrence (HR = 2.14; P = .03). Radiotherapy receipt also appeared associated with higher risk for local recurrence (HR = 1.08; 95% CI, 0.58-2.03), but the difference did not reach statistical significance.

Thirty-nine patients (16%) developed metastasis, with mean time to development of 4 years (range, 9 months to 11 years).

Houdek and colleagues reported distant DFS rates of 91% at 2 years, 84% at 5 years and 73% at 10 years.

Two factors appeared associated with increased risk for distant recurrence: local recurrence (HR = 2.76; P < .001) and high resection (HR = 2.49; P < .001).

Results showed no significant difference in OS, local RFS or distant DFS between treatment centers.

Nearly half (49%) experienced postoperative complications. These included wound complications (32%), sacral fracture (11%), acute perioperative death (2%), ischemic optic neuritis (1%) and radiation-induced sarcoma (1%).

Six of the 76 patients who experienced wound complications required a new flap.

Houdek and colleagues identified three factors that increased risk for postoperative wound complications: radiotherapy (HR = 2.63; P < .001), tumor size 9 cm or greater (HR = 2.31; P < .001) and high sacral resection (HR = 1.74; P = .02).

Twenty-seven patients (11%) experienced sacral fractures. Mean time to fracture was 3 years after surgery.

Radiotherapy (HR = 3.66; P = .001) and tumor size 9 cm or larger (HR = 3.1; P = .008) appeared associated with higher risk for sacral fractures. – by Mark Leiser

For more information:

Houdek MT. Abstract 2804922. Presented at: Connective Tissue Oncology Society Annual Meeting; Nov. 8-11, 2017; Maui.

Di sclosure: Houdek reports no relevant financial disclosures. Please see the abstract for a list of all other researchers’ relevant financial disclosures.