Abstract
PurposeTo evaluate the effectiveness of external-beam proton therapy (PT) on local control and survival in patients with skull-base chordoma.Materials and MethodsWe reviewed the medical records of patients with skull-base chordoma treated with definitive or adjuvant high-dose PT and updated their follow-up when feasible. We assessed overall survival, disease-specific survival, local control, and freedom from distant metastasis. Radiotherapy toxicities were scored using the Common Terminology Criteria for Adverse Events, version 4.0.ResultsA total 112 patients were analyzed, of whom 105 (94%) received PT and 7 (6%) received combined proton-photon therapy between 2007 and 2019. Eighty-seven patients (78%) underwent a subtotal resection, 22 (20%) a gross total resection, and 3 (3%) a biopsy alone. The median radiotherapy dose was 73.8 Gy radiobiologic equivalent (GyRBE; range, 69.6-74.4). Ninety patients (80%) had gross disease at radiotherapy and 7 (6%) were treated for locally recurrent disease following surgery. Median follow-up was 4.4 years (range, 0.4-12.6); for living patients, it was 4.6 years (range, 0.4-12.6), and for deceased patients, 4.1 years (range, 1.2-11.2). At 5 years after radiotherapy, the actuarial overall survival, disease-specific survival, local control, and freedom from distant metastasis rates were 78% (n = 87), 83% (n = 93), 74% (n = 83), and 99% (n = 111), respectively. The median time to local progression was 2.4 years (range, 0.8-7). Local control and disease-specific survival by resection status was 95% versus 70% (P = 0.28) and 100% versus 80% (P = 0.06) for gross total, versus subtotal, resection or biopsy alone, respectively. There were no serious acute toxicities (grade ≥ 3) related to radiotherapy.ConclusionHigh-dose PT alone or after surgical resection for skull-base chordoma reaffirms the favorable 5-year actuarial local control rate compared with conventional techniques with acceptable late-complication–free survival. Outcomes following gross total resection and adjuvant PT were excellent. Further follow-up of this cohort is necessary to better characterize long-term disease control and late toxicities.
Highlights
Chordomas are a rare group of neoplasms that arise from the remnant embryologic notochord
Under institutional review board approval, with patient informed consent, we reviewed the medical records of patients enrolled on a prospective outcomes-tracking protocol who were treated with high-dose proton therapy (PT) for skull-base chordomas at our institution and who met the following inclusion criteria: primary site with its epicenter arising from the base of the skull, no history of prior irradiation or evidence of metastatic disease, age 22 years or older at the time of consent, Karnofsky performance status 50, and surgery ranging from biopsy to gross total resection before PT
Maximal safe surgery to relieve symptoms related to mass effect or to improve the target geometry of highly conformal RT is the preferred initial approach to skull-base conventional chordomas
Summary
Chordomas are a rare group of neoplasms that arise from the remnant embryologic notochord They can occur anywhere along the vertebral axis, spanning cranially from the upper clivus and caudally to the sacrococcygus. In contrast to skull-base chondrosarcomas, which tend to arise from paramedian structures and have a favorable long-term prognosis, chordomas, typically indolent, are radioresistant tumors of the median neurovertebral axis that have a significantly lower 5- and 10-year local control (LC) [1]. Because these tumors require radiation doses . We report outcomes of patients treated at a single institution with dose-escalated PT for skull-base chordoma
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