Impact of surgical margins and radiation therapy on survival in spinal chordoma and chondrosarcoma: a single-institution retrospective cohort study.

OBJECTIVE Chordoma and chondrosarcoma are rare malignant bone tumors of the spine and sacrum. While en bloc resection with wide or marginal margins (Enneking appropriate [EA]) is considered the standard of care, the role of radiation therapy (RT) in the management of these traditionally radioresistant tumors remains controversial. This retrospective study aimed to evaluate treatment strategies with a focus on overall survival (OS), disease-free survival (DFS), and local recurrence-free survival (LRFS) patterns and analyze variables associated with these outcomes.

METHODS A retrospective cohort study was conducted at Vancouver General Hospital including patients with chordoma or low-grade chondrosarcoma of the mobile spine or sacrum treated surgically between 2009 and 2023. Patients were categorized into 1 of 4 groups: 1) en bloc EA resection without RT, 2) en bloc Enneking inappropriate (EI) resection with RT, 3) en bloc EI resection without RT, and 4) planned intralesional (IL) resection with or without RT. Primary outcomes were OS, DFS, and LRFS. Multivariable Cox regression was used to identify variables associated with these outcomes.

RESULTS Sixty-two patients had a median follow-up of 5.3 years. The 5-year OS, DFS, and LRFS rates were 78%, 65%, and 73%, respectively. Patients undergoing EA resection or en bloc EI resection with RT had superior OS and LRFS compared to en bloc EI resection without RT (OS 93% vs 88% vs 71%, p < 0.05; LRFS 82% vs 88% vs 52%, p < 0.05). DFS was highest in the en bloc EI resection with RT group (87%) compared to EA resection (74%; p < 0.05) and en bloc EI resection without RT (39%; p < 0.05). On multivariable analysis, age ≥ 65 years and en bloc EI resection without RT were associated with decreased OS, while en bloc EI resection without RT was the only variable independently associated with worse DFS and LRFS. All patients who underwent a planned IL resection died within 5 years.

CONCLUSIONS This study highlights the complexity of achieving EA margins in en bloc resections for spinal chordoma and chondrosarcoma. In cases in which EA resection is not feasible, adjuvant high-dose RT appears to mitigate the negative impact of EI surgery and should be strongly considered. Further studies with longer follow-up durations are warranted to confirm these findings and optimize multimodal treatment strategies.