Proton beam therapy

Conventional radiation therapy directs photons (X-rays) and electrons at tumours with the intent of eradicating the neoplastic tissue while preserving adjacent normal tissue. Radiation-induced damage to healthy tissue and second malignancies are always a concern, however, when administering radiation. Proton beam radiotherapy, one form of charged particle therapy, allows for excellent dose distributions, with the added benefit of no exit dose. These characteristics make this form of radiotherapy an excellent choice for the treatment of tumours located next to critical structures such as the spinal cord, eyes, and brain, as well as for paediatric malignancies

Randomised trial of proton vs. carbon ion radiation therapy in patients with chordoma of the skull base, clinical phase III study HIT-1-Study

<p>Abstract</p> <p>Background</p> <p>Chordomas of the skull base are relative rare lesions of the bones. Surgical resection is the primary treatment standard, though complete resection is nearly impossible due to close proximity to critical and hence also dose limiting organs for radiation therapy. Level of recurrence after surgery alone is comparatively high, so adjuvant radiation therapy is very important for the improvement of local control rates. Proton therapy is the gold standard in the treatment of skull base chordomas. However, high-LET beams such as carbon ions theoretically offer biologic advantages by enhanced biologic effectiveness in slow-growing tumors.</p> <p>Methods/design</p> <p>This clinical study is a prospective randomised phase III trial. The trial will be carried out at Heidelberger Ionenstrahl-Therapie centre (HIT) and is a monocentric study.</p> <p>Patients with skull base chordoma will be randomised to either proton or carbon ion radiation therapy. As a standard, patients will undergo non-invasive, rigid immobilization and target volume delineation will be carried out based on CT and MRI data. The biologically isoeffective target dose to the PTV in carbon ion treatment (accelerated dose) will be 63 Gy E ± 5% and 72 Gy E ± 5% (standard dose) in proton therapy respectively. Local-progression free survival (LPFS) will be analysed as primary end point. Toxicity and overall survival are the secondary end points. Additional examined parameters are patterns of recurrence, prognostic factors and plan quality analysis.</p> <p>Discussion</p> <p>Up until now it was impossible to compare two different particle therapies, i.e. protons and carbon ions directly at the same facility.</p> <p>The aim of this study is to find out, whether the biological advantages of carbon ion therapy can also be clinically confirmed and translated into the better local control rates in the treatment of skull base chordomas.</p> <p>Trial registration</p> <p>ClinicalTrials.gov identifier: NCT01182779</p

Proton radiation therapy for retinoblastoma: comparison of various intraocular tumor locations and beam arrangements

PURPOSE: To study the optimization of proton beam arrangements for various intraocular tumor locations; and to correlate isodose distributions with various target and nontarget structures. METHODS AND MATERIALS: We considered posterior-central, nasal, and temporal tumor locations, with straight, intrarotated, or extrarotated eye positions. Doses of 46 cobalt grey equivalent (CGE) to gross tumor volume (GTV) and 40 CGE to clinical target volume (CTV) (2 CGE per fraction) were assumed. Using three-dimensional planning, we compared isodose distributions for lateral, anterolateral oblique, and anteromedial oblique beams and dose-volume histograms of CTVs, GTVs, lens, lacrimal gland, bony orbit, and soft tissues. RESULTS: All beam arrangements fully covered GTVs and CTVs with optimal lens sparing. Only 15% of orbital bone received doses > or =20 CGE with a lateral beam, with 20-26 CGE delivered to two of three growth centers. The anterolateral oblique approach with an intrarotated eye resulted in additional reduction of bony volume and exposure of only one growth center. No appreciable dose was delivered to the contralateral eye, brain tissue, or pituitary gland. CONCLUSIONS: Proton therapy achieved homogeneous target coverage with true lens sparing. Doses to orbit structures, including bony growth centers, were minimized with different beam arrangements and eye positions. Proton therapy could reduce the risks of second malignancy and cosmetic and functional sequelae

Neuropsychological function in adults after high dose fractionated radiation therapy of skull base tumors.

PURPOSE: To evaluate the long term effects of high dose fractionated radiation therapy on brain functioning prospectively in adults without primary brain tumors. METHODS AND MATERIALS: Seventeen patients with histologically confirmed chordomas and low grade chondrosarcomas of the skull base were evaluated with neuropsychological measures of intelligence, language, memory, attention, motor function and mood following surgical resection/biopsy of the tumor prior to irradiation, and then at about 6 months, 2 years and 4 years following completion of treatment. None received chemotherapy. RESULTS: In the patients without tumor recurrence or radiation necrosis, there were no indications of adverse effects on cognitive functioning in the post-acute through the late stages after brain irradiation. Even in patients who received doses of radiation up to 66 Cobalt Gy equivalent through nondiseased (temporal lobe) brain tissue, memory and cognitive functioning remained stable for up to 5 years after treatment. A mild decline in psychomotor speed was seen in more than half of the patients, and motor slowing was related to higher radiation doses in midline and temporal lobe brain structures. CONCLUSION: Results suggest that in adults, tolerance for focused radiation is relatively high in cortical brain structures

The role of radiotherapy in the treatment of subtotally resected benign meningiomas

Thirty-six patients with benign meningioma were treated for primary or recurrent disease by subtotal resection and external beam irradiation from 1968-1986 at Massachusetts General Hospital. Comparison is made with 79 patients treated by subtotal surgery alone from 1962-1980. Progression-free survival for 17 patients irradiated after initial incomplete surgery was 88% at 8 years compared with 48% for similar patients treated by surgery alone (p = 0.057). 16 patients incompletely resected at time of first recurrence were irradiated and 78% were progression-free at 8 years while 11% of a similar group treated by surgery alone were progression free (p = 0.001). Long term overall survival was high and similar in both control and study groups. Two patients were irradiated at second recurrence and 1 patient at third recurrence. Twenty-five patients were treated with photons alone and have a median follow-up of 57 months, 6 patients have recurred at doses 45-60 Gy. Eleven patients were treated with combined 10 MV photons and 160 MV protons utilizing 3-D treatment planning. These patients have been followed for a median of 53 months and none have failed to date. Eight of 11 received 54-60.4 Gy and 3/11 greater than 64.48 Gy. Sex, age, pathology grade and score, surgery and timing of radiation therapy were not associated with significant differences in failure patterns within the irradiated study group (p less than 0.1). Complications have been seen in 6 irradiated patients

Base of skull chordoma. A correlative study of histologic and clinical features of 62 cases

Background. Chordomas are uncommon primary malignant tumors of bone that typically occur in the axial skeleton including the sacrum, vertebrae, and skull base. The base of skull tumors usually are not amenable to complete surgical resection, and most require postoperative radiotherapy. The natural history of skull base chordoma is typified by slow locally invasive tumor progression and eventual death, although few parameters are known that allow stratification of patients into prognostic groups. Methods. Sixty‐two patients with skull base chordomas treated at the Massachusetts General Hospital by proton beam irradiation therapy with at least 2 years of follow‐up information were reviewed in an attempt to identify clinical and pathologic parameters that predicted outcome. Results. Female sex, tumor necrosis in preradiation treatment biopsy, and tumor volume in excess of 70 ml were each independent predictors of shortened overall survival after radiation therapy for skull base chordoma. Conclusions. Stratification of patients with skull base chordoma into poor and good outcome groups can be performed using the three parameters identified in our study. In addition, the striking difference in survival between the sexes suggests that further investigations of these tumors should include determination of their hormonal receptor status and consideration of hormonal manipulation in their management