Analysis of Early Outcomes of Pencil Beam Proton Therapy Compared with Passive Scattering Proton Therapy for Clival Chordoma

Sukwoo Hong, Nadia Laack, Anita Mahajan, Garret Choby, Erin O'Brien, Janalee Stokken, Jeffrey Janus, Jamie J. Van Gompel

Research output: Contribution to journalArticlepeer-review


Objective: To assess the early outcomes of the following 2 types of proton therapy: passive scattering proton therapy (PSPT) and pencil beam proton therapy (PBPT). Methods: The consecutive patients who had surgery in our facility were retrospectively reviewed. Results: Thirty-two patients were identified (PBPT 22 patients [69%]). The mean (±standard deviation [SD]) tumor size was 3.8 ± 1.8 cm, and the most common location was the upper clivus (41%). Four cases (13%) were revision surgeries referred from elsewhere, and 2 cases underwent additional surgery elsewhere to achieve near-total resection before radiation. The cerebrospinal fluid leak occurred in 3 patients (9%). The mean (±SD) prescribed dose of PSPT and PBPT was 74 ± 3 Gy and 72 ± 3 Gy, respectively (P = 0.07). The mean (±SD) fractionation of PSPT and PBPT was 39 ± 2 and 36 ± 2, respectively (P = 0.001). Radiation toxicities were recorded in endocrine (11 patients [34%]), ophthalmic (3 patients [9%]), otologic (7 patients [22%]), and radiation necrosis (4 patients [13%]). PSPT was associated with endocrinopathy (odds ratio [OR], 10.5; 95% confidence interval, 1.86–59.4, P = 0.008), and radiation dose was associated with otologic toxicity (OR 1.57; 95% confidence interval, 1.02–2.44; P = 0.04). The gross-near total resection group had better progression-free survival than the subtotal resection group regardless of radiation therapy (P = 0.01). Overall, 3-year progression-free survival was 73%, and 5-year overall survival was 93%. Conclusions: The PBPT group showed comparable outcome to the PSPT group. The degree of resection was more important than the modality of proton therapy. Further follow-up and cases are necessary to evaluate the benefit of PBPT.

Original languageEnglish (US)
Pages (from-to)e644-e653
JournalWorld neurosurgery
StatePublished - Mar 2023


  • Brachyury
  • Chordoma
  • Endoscopic
  • Skull base

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology


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