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Radiother Oncol. 2016 Jul;120(1):169-74. doi: 10.1016/j.radonc.2016.05.011. Epub 2016 May 28.

Long term outcomes of patients with skull-base low-grade chondrosarcoma and chordoma patients treated with pencil beam scanning proton therapy.

Author information

1
Center for Proton Therapy, Paul Scherrer Institute, Switzerland; University of Bern, Switzerland; University of Zürich, Switzerland. Electronic address: damiencharles.weber@uzh.ch.
2
Center for Proton Therapy, Paul Scherrer Institute, Switzerland.
3
Unité d'Epidemiologie Clinique, Hôpitaux Universitaire de Genève, Switzerland.
4
Center for Proton Therapy, Paul Scherrer Institute, Switzerland; ETH, Zürich, Switzerland.

Abstract

PURPOSE:

To evaluate the long term tumor control and toxicity of skull base tumors treated with pencil beam scanning proton therapy (PT).

MATERIALS AND METHODS:

PT was delivered to 151 (68%) and 71 (32%) chordoma and chondrosarcoma (ChSa) patients, respectively. Mean age of patients was 40.8±18.4years and the male to female ratio was 0.53. The postoperative tumor was abutting the brainstem or optic apparatus in 71 (32.0%) patients. The postoperative mean gross tumor volume (GTV) was 35.7±29.1cm(3). The delivered mean PT dose was 72.5±2.2GyRBE.

RESULTS:

After a mean follow-up of 50 (range, 4-176) months, 35 local (15.8%) failures were observed between 10.9 and 85.4months. The estimated 7-year LC rate for chordoma (70.9%; CI95% 61.5-81.8) was significantly lower compared to the LC rate for ChSa patients (93.6%; 95%CI 87.8-99.9; P=0.014). The estimated 7-year distant metastasis-free- and overall survival rate was 91.6% (95%CI 91.6-98.6) and 81.7% (95%CI 74.7-89.5), respectively. On multivariate analysis, optic apparatus and/or brainstem compression, histology and GTV were independent prognostic factors for LC and OS. The 7-year high grade toxicity-free survival was 87.2 (95%CI 82.4-92.3).

CONCLUSIONS:

PBS PT is an effective treatment for skull base tumors with acceptable late toxicity. Optic apparatus and/or brainstem compression, histology and GTV allow independent prediction of the risk of local failure and death in skull base tumor patients.

KEYWORDS:

Chondrosarcoma; Chordoma; Pencil beam scanning; Proton therapy; Skull base tumors

PMID:
27247057
DOI:
10.1016/j.radonc.2016.05.011
[Indexed for MEDLINE]

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