Prognostic factors for spinal chordomas and chondrosarcomas treated with postoperative pencil-beam scanning proton therapy: a large, single-institution experience.

Murray, Fritz R; Snider, James W; Schneider, Ralf A; Walser, Marc; Bolsi, Alessandra; Pica, Alessia; Lomax, Antony J; Weber, Damien C. (2020). Prognostic factors for spinal chordomas and chondrosarcomas treated with postoperative pencil-beam scanning proton therapy: a large, single-institution experience. Journal of neurosurgery - spine, 32(6), pp. 921-930. American Association of Neurological Surgeons 10.3171/2019.11.SPINE1927

Text _Journal_of_Neurosurgery_Spine__Prognostic_factors_for_spinal_chordomas_and_chondrosarcomas_treated_with_postoperative_pencil-beam_scanning_proton_therapy_a_large__single-institution_experience-1.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (1MB)

OBJECTIVE

The aim of this paper was to evaluate the prognostic factors in surgical and adjuvant care for spinal chordomas and chondrosarcomas after surgery followed by high-dose pencil-beam scanning proton therapy (PBS-PT).

METHODS

From 1997 to 2016, 155 patients (61 female patients; median age 55 years) with spinal (cervical, n = 61; thoracic, n = 29; lumbar, n = 13; sacral, n = 46; pelvic, n = 6) classic chordomas (n = 116) and chondrosarcomas (n = 39; most were low grade) were treated with maximal safe resection followed by PBS-PT (median dose prescribed: 74 Gy [relative biological effectiveness], range 48.6-77 Gy). The majority of patients (n = 153, 98.7%) had undergone at least 1 resection prior to PBS-PT (median 1, range 0-5; biopsy only, n = 2). Fewer than half (45.1%) of the surgeries were rated as gross-total resections (GTRs) prior to PBS-PT. Surgical stabilization (SS) was present in 39% of all patients (n = 60). Ninety-one patients (59%) presented with macroscopic tumor at the start of PBS-PT. The median follow-up duration was 64.7 months (range 12.2-204.8 months).

RESULTS

The 5-year local tumor control, disease-free survival (DFS), and overall survival were 64.9% (95% CI 56.3%-73.5%), 59.4% (95% CI 50.6%-68.2%), and 77.9% (95% CI 70.6%-85.2%), respectively. In total, 63 patients (40.6%) experienced failure during the follow-up period: local only in 32 (20.6%), distal only in 7 (4.5%), local + distal in 19 (12.3%), surgical pathway failure (SPF) only in 2 (1.3%), local + SPF in 2 (1.3%), and distal + SPF in 1 (< 1%). Univariate analysis identified gross residual disease, the presence of SS, and treatment era prior to 2008 as highly significant for worse outcome, with all 3 remaining significant on multivariate analysis. The type of surgery (GTR or subtotal resection/biopsy) and whether GTR was achieved by en bloc or curettage did not show a significant prognostic effect. Surgical complications prior to PBS-PT were present in 42.5% of all surgically treated patients and were seen more commonly in patients with multiple surgical interventions (p = 0.005) and those operated on with the intent of en bloc resection (p = 0.006).

CONCLUSIONS

The extent of resection and metallic stabilization substantially influenced clinical outcomes for patients with spinal chordoma or chondrosarcoma despite high-dose adjuvant PBS-PT. Optimal upfront surgical management of these tumors continues to include GTR, as possible, with prompt adjuvant proton therapy.

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