Long-term clinical outcomes of hypofractionated stereotactic radiotherapy using the CyberKnife robotic radiosurgery system for jugular foramen schwannomas

OBJECTIVE

Jugular foramen schwannomas (JFSs) are rarely seen, benign tumors with slow growth. Today, management options for JFSs include observation, surgery, and radiation. However, the optimal treatment strategy remains controversial. Stereotactic radiosurgery serves as a minimally invasive alternative or adjuvant therapeutic regimen of microsurgery. Gamma Knife radiosurgery is suitable for patients with JFS who have small- and medium-sized tumors and normal cranial nerve (CN) function. Hypofractionated stereotactic radiotherapy (HSRT) offers a potential radiobiological advantage and may result in better preservation of normal structures compared to single-fraction stereotactic radiosurgery. The aim of the article was to review the clinical and radiographic outcomes of patients with JFS who were treated using HSRT.

METHODS

The authors retrospectively analyzed 74 patients with JFS who received HSRT between January 2009 and January 2020 in the authors' center. Among them, 53 patients were newly diagnosed with JFS, 19 patients had a previous history of microsurgical resection, and the other 2 patients underwent CyberKnife because of tumor recurrence after Gamma Knife radiosurgery. A total of 73 patients had preexisting CN symptoms and signs. The median tumor volume was 14.8 cm3 (range 0.5-41.2 cm3), and most of them (70.3%) were ≥ 10 cm3. The radiation dose regimen was prescribed depending on the tumor size, and more fractions were used in larger tumors. The median margin doses prescribed were 18.2 Gy/2 fractions, 21.0 Gy/3 fractions, and 21.6 Gy/4 fractions.

RESULTS

The median follow-up was 103 months (range 18-158 months). After treatment, 42 (56.8%) patients had tumor regression, 27 (36.5%) patients had stable tumors, and 5 (6.8%) experienced tumor progression. Among them, MRI revealed that 1 patient had a complete response. Three patients received surgery at a median of 25 months because of tumor progression. One patient underwent ventriculoperitoneal shunt insertion for hydrocephalus that developed after HSRT independent of tumor progression. The 5-year progression-free survival rate was 93.2%. Preexisting cranial neuropathies improved in 46 patients, remained stable in 14, and worsened in 14.

CONCLUSIONS

HSRT proved to be a safe and effective primary or adjuvant treatment strategy for JFSs, although 14 patients (18.9%) experienced some degree of delayed symptomatic deterioration posttreatment. This therapeutic option was demonstrated to provide both excellent tumor control and improvement in CN function.

Clinical and Imaging Outcomes After Trigeminal Schwannoma Radiosurgery: Results From a Multicenter, International Cohort Study

BACKGROUND AND OBJECTIVES

An international, multicenter, retrospective study was conducted to evaluate the long-term clinical outcomes and tumor control rates after stereotactic radiosurgery (SRS) for trigeminal schwannoma.

METHODS

Patient data (N = 309) were collected from 14 international radiosurgery centers. The median patient age was 50 years (range 11-87 years). Sixty patients (19%) had prior resections. Abnormal facial sensation was the commonest complaint (49%). The anatomic locations were root (N = 40), ganglion (N = 141), or dumbbell type (N = 128). The median tumor volume was 4 cc (range, 0.2-30.1 cc), and median margin dose was 13 Gy (range, 10-20 Gy). Factors associated with tumor control, symptom improvement, and adverse radiation events were assessed.

RESULTS

The median and mean time to last follow-up was 49 and 65 months (range 6-242 months). Greater than 5-year follow-up was available for 139 patients (45%), and 50 patients (16%) had longer than 10-year follow-up. The overall tumor control rate was 94.5%. Tumors regressed in 146 patients (47.2%), remained unchanged in 128 patients (41.4%), and stabilized after initial expansion in 20 patients (6.5%). Progression-free survival rates at 3 years, 5 years, and 10 years were 91%, 86%, and 80 %. Smaller tumor volume (less than 8 cc) was associated with significantly better progression-free survival ( P = .02). Seventeen patients with sustained growth underwent further intervention at a median of 27 months (3-144 months). Symptom improvement was noted in 140 patients (45%) at a median of 7 months. In multivariate analysis primary, SRS ( P = .003) and smaller tumor volume ( P = .01) were associated with better symptom improvement. Adverse radiation events were documented in 29 patients (9%).

CONCLUSION

SRS was associated with long-term freedom (10 year) from additional management in 80% of patients. SRS proved to be a valuable salvage option after resection. When used as a primary management for smaller volume tumors, both clinical improvement and prevention of new deficits were optimized.

Stereotactic radiosurgery for the treatment of hypoglossal schwannoma: a multi-institutional retrospective study

BACKGROUND

Surgical removal has been performed as the first line treatment for symptomatic or enlarging hypoglossal schwannomas (HS). Stereotactic radiosurgery (SRS) offers a minimally invasive approach that may afford long-term tumor control for patients with HS particularly those who refuse or are unfit for surgery. This study evaluates outcomes after SRS performed for both newly diagnosed and residual tumors after incomplete resection.

METHODS

This retrospective, multi-institutional study involved patients treated with adjuvant or primary SRS for HS. The study end-points included local tumor response, clinical outcomes, and procedure-related complications. All the patients had Gamma Knife SRS.

RESULTS

The cohort included 12 patients (five females), median age at SRS 49.5 years (range, 37-76)]. The median tumor target volume was 5.9 cm³ (range, 0.7-27.23). At median imaging follow-up of 37 months (range, 6-153), tumor control was achieved in 11 patients. Tumor enlargement that was managed with surgical resection was noted at the 6-month follow-up in one patient. At median clinical follow-up of 30.5 months (range, 6-157), stability, or improvement of all pre-SRS signs and symptoms was noted in nine patients. Two patients experienced worsening of at least one pre-existing symptoms or sign. New-onset trapezius weakness was noted in one patient and tongue atrophy in two patients.

CONCLUSION

Single-fraction SRS appears to be a safe and effective upfront and adjuvant treatment option for HS. SRS may be recommended as an alternative to surgery for patients presenting with HS or as an adjuvant treatment following subtotal resection and at HS recurrence.

Stereotactic radiosurgery for hypoglossal schwannoma

Hypoglossal schwannomas (HS) are extremely rare neoplasms. Surgical resection has historically been the treatment of choice but carries a significant risk of postoperative neurological deficits and mortality. Stereotactic radiosurgery (SRS) is a minimally invasive approach that may afford long-term tumour growth. However, literature to determine the safety and effectiveness of SRS in the treatment of HS is scarce. We report on a patient who presented with progressive headache and dysphagia as well as tongue deviation to the left, due to a space-occupying lesion, consistent on brain MRI with a left HS. Primary SRS using a prescription dose of 12 Gy in a single fraction was used to treat the tumour without complications. By last follow-up, the tumour regressed, and the patient's symptoms improved. Our case shows that radiosurgery can be safe and effective for the management of HS.

Gamma Knife Stereotactic Radiosurgery for Nonvestibular Cranial Nerve Schwannomas

BACKGROUND

Nonvestibular cranial schwannomas represent a rare type of benign intracranial tumor. Few studies have evaluated the use of stereotactic radiosurgery (SRS) as a primary management option for these lesions. We performed a retrospective review of our institution's experience focusing on efficacy with regard to tumor control and clinical symptom stabilization as well as treatment safety.

METHODS

Patients were included if they underwent at least 1 SRS procedure for a nonvestibular schwannoma and had at least 6 months of available imaging follow-up. Demographic, SRS dose planning, clinical, and imaging data were collected from chart reviews of treated patients. χ² and Kaplan-Meier analyses were performed.

RESULTS

Between 2004 and 2016, 35 schwannomas were treated in 34 patients. Median follow-up was 48 months. Median age at time of treatment was 51 years. Three patients had neurofibromatosis 2. Schwannoma location was trigeminal (57%), facial (20%), jugular foramen (14%), abducens (6%), and trochlear (3%). Median margin dose delivered was 13 Gy. The 5-year and 10-year tumor control rates were 94.4% and 88.5%, respectively. Presenting clinical symptoms stabilized or improved in 79% of cases after radiosurgery, and new or worsening symptoms were seen in 21%.

CONCLUSIONS

SRS is a safe and effective modality for treatment of nonvestibular cranial nerve schwannomas.

Primary Parapharyngeal Space Tumors in a Mexican Cancer Center

OBJECTIVE: To describe clinical and demographic characteristics of the parapharyngeal space tumors and assess surgical approaches used to treat them at our institution.

METHODS: A retrospective and descriptive study of the parapharyngeal space tumors, excluding paragangliomas, treated from June 1991 to October 2002 in a cancer center. The study population included 21 patients, 8 men and 13 women, average age of 41 years (range, 20 to 70 years). Fine needle biopsy was done in 5 (24%) patients. Computed tomography (CT) was performed in all patients, and only a few required magnetic resonance image (MRI).

RESULTS: Surgical approaches included transcervical alone or in combination with parotidectomy, transoral, or transmandibular (mandibular swing) approach. Laminectomy and segmentary approaches were also performed in 1 patient each. Sixteen (76%) patients had benign lesions and 5 (24%) had malignant tumors. Neurogenic tumors represented 57% of all tumors. Mean tumor size was of 6.7 cm (range, 3 to 11 cm). Six (29%) patients received adjuvant radiotherapy. Complications occurred in 6 (29%) patients, 4 (19%) of which were nervous injuries associated with peripheral nerve sheath tumors. Median disease-free follow-up survival was 33 months (range, 2 to 184 months) despite being an heterogeneous group of histologies.

CONCLUSION: Parapharyngeal space is a rare location for head and neck tumors. Cervical approach should be the first choice for large tumors; transoral approach is reserved for tumors less than 3 cm. Conversion to mandibular swing approach when the cervical approach is not offering proper exposure for tumor resection is indicated. Preoperative histologic diagnosis is not required. Nevertheless, CT scan should always be performed in order to exclude paragangliomas, distinguish prestyloid from poststyloid lesions, and to assess the extension of the tumor as well as its relationship with adjacent structures.

A case of recurrent malignant triton tumor successfully treated with radiotherapy

A 15-year-old female was previously admitted to another hospital because of painless swelling of the lateral right nasal ala for 2 months. Magnetic resonance imaging revealed an expansive enhancing lesion in close proximity to the anterior surface of the right maxillary sinus and lateral wall of the right nasal cavity. Tumor extirpation was performed via the supragingival transantral approach under general anesthesia. Histopathological study revealed a malignant triton tumor (MTT) arising from the nasal vestibule. The patient was referred to our department for consultation regarding additional treatment. Because the surgical margin was positive and MTT has high malignant potential, we recommended expansion re-surgical treatment following immediate free-flap reconstruction and postoperative radiotherapy, but family consent was not obtained. Tumor regrowth was noted 1 month after her first visit to our department. The patient and her family accepted radiotherapy instead of surgical treatment. Complete remission was achieved by radiotherapy alone. No local recurrence or distant metastasis was observed for 30 months after radiotherapy. The conventional mode of treatment for MTT is radical excision followed by high-dose radiotherapy. However, this case is remarkable because our patient experienced complete remission by simple radiotherapy.

Potential of boron neutron capture therapy (BNCT) for malignant peripheral nerve sheath tumors (MPNST)

Malignant peripheral nerve sheath tumors (MPNST) are relatively rare neoplasms with poor prognosis. At present there is no effective treatment for MPNST other than surgical resection. Nonetheless, the anti-tumor effect of boron neutron capture therapy (BNCT) was recently demonstrated in two patients with MPNST. Subsequently, tumor-bearing nude mice subcutaneously transplanted with a human MPNST cell line were injected with p-borono-L-phenylalanine (L-BPA) and subjected to BNCT. Pathological studies then revealed that the MPNST cells were selectively destroyed by BNCT.

Preclinical evaluation of the combination of mTOR and proteasome inhibitors with radiotherapy in malignant peripheral nerve sheath tumors

About one half of malignant peripheral nerve sheath tumors (MPNST) have Neurofibromin 1 (NF1) mutations. NF1 is a tumor suppressor gene essential for negative regulation of RAS signaling. Survival for MPNST patients is poor and we sought to identify an effective combination therapy. Starting with the mTOR inhibitors rapamycin and everolimus, we screened for synergy in 542 FDA approved compounds using MPNST cells with a native NF1 loss in both alleles. We further analyzed the cell cycle and signal transduction. In vivo growth effects of the drug combination with local radiation therapy (RT) were assessed in MPNST xenografts. The synergistic combination of mTOR inhibitors with bortezomib yielded a reduction in MPNST cell proliferation. The combination of mTOR inhibitors and bortezomib also enhanced the anti-proliferative effect of radiation in vitro. In vivo, the combination of mTOR inhibitor (everolimus) and bortezomib with RT decreased tumor growth and proliferation, and augmented apoptosis. The combination of approved mTOR and proteasome inhibitors with radiation showed a significant reduction of tumor growth in an animal model and should be investigated and optimized further for MPNST therapy.

A quality assurance method that utilizes 3D dosimetry and facilitates clinical interpretation

PURPOSE

To demonstrate a new three-dimensional (3D) quality assurance (QA) method that provides comprehensive dosimetry verification and facilitates evaluation of the clinical significance of QA data acquired in a phantom. Also to apply the method to investigate the dosimetric efficacy of base-of-skull (BOS) intensity-modulated radiotherapy (IMRT) treatment.

METHODS AND MATERIALS

Two types of IMRT QA verification plans were created for 6 patients who received BOS IMRT. The first plan enabled conventional 2D planar IMRT QA using the Varian portal dosimetry system. The second plan enabled 3D verification using an anthropomorphic head phantom. In the latter, the 3D dose distribution was measured using the DLOS/Presage dosimetry system (DLOS = Duke Large-field-of-view Optical-CT System, Presage Heuris Pharma, Skillman, NJ), which yielded isotropic 2-mm data throughout the treated volume. In a novel step, measured 3D dose distributions were transformed back to the patient's CT to enable calculation of dose-volume histograms (DVH) and dose overlays. Measured and planned patient DVHs were compared to investigate clinical significance.

RESULTS

Close agreement between measured and calculated dose distributions was observed for all 6 cases. For gamma criteria of 3%, 2 mm, the mean passing rate for portal dosimetry was 96.8% (range, 92.0%-98.9%), compared to 94.9% (range, 90.1%-98.9%) for 3D. There was no clear correlation between 2D and 3D passing rates. Planned and measured dose distributions were evaluated on the patient's anatomy, using DVH and dose overlays. Minor deviations were detected, and the clinical significance of these are presented and discussed.

CONCLUSIONS

Two advantages accrue to the methods presented here. First, treatment accuracy is evaluated throughout the whole treated volume, yielding comprehensive verification. Second, the clinical significance of any deviations can be assessed through the generation of DVH curves and dose overlays on the patient's anatomy. The latter step represents an important development that advances the clinical relevance of complex treatment QA.

Chemotherapy in metastatic malignant triton tumor: report on two cases

Malignant triton tumor (MTT) is a rare, highly malignant nerve sheath tumor with rhabdomyoblastic differentiation. Initial debulking surgery followed by adjuvant therapy is the current treatment of choice, but has very limited efficacy when optimal cytoreduction is not achieved by surgical procedure. Neoadjuvant therapy for MTT, to potentially facilitate subsequent surgery, eradicate micrometastatic lesions and, therefore, improve the therapeutical outcome, has never before been presented in literature. Here, we report on the multimodal management of two cases of advanced and metastatic MTT. Treatment modalities involved neoadjuvant and adjuvant chemotherapy, surgical resection, and radiation. In both cases, integrated Positron Emission Tomography/Computed Tomography (PET/CT) emerged as an important diagnostic tool for the reliable assessment of MTT response and metabolic remission.

Ocular neuromyotonia with spastic lid closure

Ocular neuromyotonia is characterized by tonic spasms of extraocular muscles evoked by eccentric gaze that induces transient strabismus and diplopia. We report the case of a 70-year-old woman who initially presented with unilateral deficits in fifth and sixth cranial nerve functions attributed to a fifth cranial nerve schwannoma. After radiation treatment, she developed neuromyotonia and synkinesis of the ipsilateral third cranial nerve. During the attacks of neuromyotonia, the left eyelids were often spastically closed, a phenomenon not previously reported. The ocular neuromyotonia regressed spontaneously within 3 years, but components of the synkinesis persisted. Ephaptic transmission in a damaged third cranial nerve may be responsible for the neuromyotonia and synkinesis. Synkinesis is a more enduring manifestation.

CyberKnife Radiosurgery for Extremity Schwannomas: Technical Note and Case Report

Peripheral nerve sheath tumors are uncommon. Although surgical resection remains the treatment of choice for most symptomatic lesions, the potential for intraoperative injury to the nerve is not insignificant. This concern is of particular relevance in those patients with a genetic proclivity to develop multiple peripheral nerve sheath tumors. Here we report four symptomatic peripheral extremity schwannomas all in 1 patient who was treated with CyberKnife radiosurgery. The radiosurgical Dmax in each case was between 24.4 and 25.32 Gy. At 1-year follow-up, patient symptoms had been ameliorated, no tumor had increased in size and there was no compromise in neurological function. Although this experience is still very preliminary, it represents the first published description of a peripheral nerve sheath tumor being treated with stereotactic radiosurgery.

Primary malignant schwannoma of the cervical plexus with melanocytic differentiation

Primary malignant schwannomas are rare neoplasms of nerve sheath origin, especially in the location of the head and neck where few cases are described in the literature. These tumours may pose a diagnostic dilemma in the work-up of a neck mass. The case presented here is of a malignant schwannoma that originated in the cervical plexus with the rare histological feature of melanocytic differentiation. Histopathological examination with immunostaining techniques is essential for the diagnosis of these tumours. The management of these neoplasms is still controversial, although the treatment of choice is radical surgical excision of the lesion. The role of postoperative radiotherapy or chemotherapy is not clear, although some authors recommend its use to prevent local recurrence, for unresectable recurrent tumours or in cases of distant metastases.

Uptake of 4-borono-2-[18F]fluoro-L-phenylalanine in sporadic and neurofibromatosis 2-related schwannoma and meningioma studied with PET

PURPOSE

Meningiomas and schwannomas associated with neurofibromatosis 2 (NF2) are difficult to control by microsurgery and stereotactic radiotherapy alone. Boron neutron capture therapy (BNCT) is a chemically targeted form of radiotherapy requiring increased concentration of boron-10 in tumour tissue. PET with the boron carrier 4-borono-2-[(18)F]fluoro-L-phenylalanine ([(18)F]FBPA) allows investigation of whether 4-borono-L-phenylalanine (BPA) concentrates in NF2 tumours, which would make BNCT feasible.

METHODS

We studied dynamic uptake of [(18)F]FBPA in intracranial meningiomas (n=4) and schwannomas (n=6) of five sporadic and five NF2 patients. Tracer input function and cerebral blood volume were measured. [(18)F]FBPA uptake in tumour and brain was assessed with a three-compartmental model and graphical analysis. These, together with standardised uptake values (SUVs), were used to define tumour-to-brain [(18)F]FBPA tissue activity gradients.

RESULTS

Model fits with three parameters K (1) (transport), k (2) (reverse transport) and k (3) (intracellular metabolism) were found to best illustrate [(18)F]FBPA uptake kinetics. Maximum SUV was two- to fourfold higher in tumour as compared with normal brain and independent of NF2 status. The increased uptake was due to higher transport of [(18)F]FBPA in tumour. In multiple-time graphical analysis (MTGA, Gjedde-Patlak plot) the tumour-to-brain [(18)F]FBPA influx constant (K (i) -MTGA) ratios varied between 1.8 and 5.4 in NF2-associated tumours while in sporadic tumours the ratio was 1-1.4.

CONCLUSION

[(18)F]FBPA PET offers a viable means to evaluate BPA uptake in meningiomas and schwannomas in NF2. Based on our results on tumour uptake of [(18)F]FBPA, some of these benign neoplasms may be amenable to BNCT.

Comparative Planning Study for Proton Radiotherapy of Benign Brain Tumors

PURPOSE

A comparative study of different systems for proton-based radiotherapy was conducted.

MATERIAL AND METHODS

The Paul Scherrer Institute method for spot scanning was compared with the systems for passive scattering from the Helax-TMS and the Varian Eclipse. Twelve cases of "benign" brain tumors were considered (meningiomas, neurinomas, and hypophyseal adenomas). Organs at risk included chiasm, brainstem, eyes and optic nerves as well as the not otherwise specified healthy brain tissue in view of long-term toxicity.

RESULTS

The results showed that high target coverage was achievable (V(90) > 98% for all systems). Plans designed with the spot-scanning technique presented the minimum involvement of healthy tissue (e. g., the lowest maximum significant dose to healthy brain [25.6 Gy] or the lowest conformity index [CI(95) = 1.3], between 38% and 46% lower than for the other techniques).

CONCLUSION

In this study, no definitive indication of superiority of any technique can be drawn but spot scanning can better conform dose distributions and minimize the irradiation of healthy volumes at medium to low dose levels, a factor of interest when long life expectancy is considered.

Diffusion Changes in a Tumor and Peritumoral Tissue After Stereotactic Irradiation for Brain Tumors

OBJECTIVE

Changes in apparent diffusion coefficient (ADC) in a tumor and peritumoral tissue after stereotactic irradiation (STI) were evaluated, and then the therapeutic efficacy of ADC measurement was assessed.

METHODS

In 20 tumors, diffusion-weighted imaging within 1 week before and 2-4 weeks after STI was performed. The normalized ADC (nADC) was measured. The nADCs in the tumor and peritumoral region before STI were compared with those after STI and the change in tumor nADC compared with the change in tumor size.

RESULTS

The nADC of the tumors was significantly higher 2-4 weeks after STI compared with that before STI. The nADC of the peritumoral regions 2-4 weeks after STI did not differ significantly from that before STI. A significant difference in the nADC at 2-4 weeks after STI was observed between the responder and nonresponder groups.

CONCLUSIONS

Changes in nADC as measured by diffusion-weighted imaging can predict response to STI.

Clinical Results: Radiosurgery and Radiotherapy of Cranial Nerve Schwannomas

Stereotactic radiosurgery and fractionated radiotherapy are two attractive low-morbidity alternatives to surgical resection for managing cranial nerve schwannomas. Treatment outcomes from these radiation treatment approaches are well documented with long-term outcome studies from multiple institutions. Differences in outcome between these two modalities are difficult to define clearly. The low morbidity and high long-term tumor control rates with radiation treatment have made it the choice of many patients who opt for active initial management for small- or medium-sized cranial nerve schwannomas.

Malignant epithelioid cranial nerve sheath tumor: case report of a radiation response

Malignant epithelioid nerve sheath tumors (MESs) especially those involving intracranial cranial nerves are rare and thought to be radioresistant. We report a case of a MES involving the Vth and VIIth cranial nerves responsive to radiotherapy. A 41-year-old man with progressive left facial weakness underwent an MRI that disclosed an enhancing lesion involving both V3 cranial nerve and the distal VIIth nerve. Biopsy confirmed a malignant epithelioid schwannoma. The tumor was resected but residual tumor was present at the cut end of the infraorbital nerve, within the oral cavity and at the brainstem. Positive excision margins were irradiated to 60 Gy/30 fractions by a wedge pair technique extending from the inferior orbit to C2. Tumor was controlled for 38 months and then radiographic recurrence was resected from the infratemporal fossa outside the irradiated field.A new primary MES tumor developed at 69 months at the C1/C2 root levels at the lower edge of the previously irradiated field. It was subtotally resected but by 77 months residual tumor had grown inferiorly down to C5 so this area was re-irradiated with a complicated 7-field approach to spare spinal cord. Initially the tumor responded but ultimately progressed posteriorly where radiation dose was limited by spinal cord tolerance. New involvement of the Xth cranial nerve was noted. The patient expired from brainstem compression 7 years after initial radiotherapy. The long-term control of the original tumor despite positive margins argues for the use of radiotherapy in the treatment of these tumors.

Retroperitoneal schwannoma presenting as an ovarian tumor

A mass in the left annexal zone was discovered in a 56-year-old woman at the Department of General Surgery and was diagnosed as ovarian cancer. After the operation the mass appeared histologically to be retroperitoneal leyiomiosarcoma and because of residual disease, confirmed by computed tomography (CT) and nuclear magnetic resonance (NMR), complementary radiotherapy was carried out. Restaging supported the persistence of the tumor and so a second laparotomy was performed with complete tumor resection; the pathologic diagnosis was retroperitoneal benign schwannoma. The importance of careful preoperative imaging, such as echography, CT, NMR, arteriography and urography should be stressed for a correct clinical and surgical approach. Moreover, considering that in some selected clinical cases these tumors could be confused with others deriving from contiguous organs and structures, a different surgical approach may be needed together with dedicated and expert surgeons.

Pancreatic schwannoma. A case report and review of the literature

CONTEXT

Pancreatic schwannomas are rare neoplasms. These tumors vary in size and two thirds are partially cystic which grossly mimic pancreatic cystic lesions. Computed tomography and magnetic resonance imaging are the primary initial imaging modalities. Definitive diagnosis is typically made at the time of laparotomy following biopsy. Surgical resection is the mainstay of treatment.

CASE REPORT

A 69-year-old woman presented with abdominal pain in the epigastric and left upper quadrant. The patient had no systemic symptom and laboratory results including tumor markers were negative. A CT scan of the abdomen showed a 5 cm mass arising from the head of the pancreas. Needle biopsy revealed a mass consistent with schwannoma. At laparotomy, a large pancreatic head mass was found to encase the superior mesenteric artery, and portal vein confluence. Frozen biopsy showed schwannoma. Curative resection was deferred due to extensive vascular involvement and favorable tumor biology. A gastrojejunostomy was performed and radiation therapy was instituted post-operatively.

CONCLUSIONS

Only 24 cases of pancreatic schwannoma had been previously reported. Definitive diagnosis is obtained with routine histology. Most tumors are benign and surgical resection is curative. The role of radiation therapy in the management of unresectable tumors is still unclear.

Malignant triton tumor of the lumbar spine

STUDY DESIGN

A case report of surgically treated malignant triton tumor of the L2 nerve root.

OBJECTIVES

To discuss treatment methods of the rare malignant triton tumor.

SUMMARY OF BACKGROUND DATA

Malignant peripheral nerve sheath tumors are neoplasms that most often arise in peripheral nerves or in neurofibromas. Malignant triton tumor is a histologic variant of those tumors.

METHODS

A 58-years-old male patient was admitted with severe back and leg pain. Magnetic resonance imaging revealed a dumbbell-shaped tumor over the right L2 nerve root. The tumor mass was removed posteriorly and the spine was stabilized by transpedicular screws followed by radiation therapy.

RESULTS

The tumor was diagnosed as "malignant triton tumor." There was no sign of metastasis during the 8 months of follow up.

CONCLUSIONS

In this case, the diagnosis of triton tumor is based solely on microscopic evidence of the neural tissue accompanied by rhabdomyoblasts and immunohistochemical examination. Patients with malignant triton tumors are usually younger than age 35. Our patient is 1 of the oldest patients with tumor occurrence in the spinal canal. Although our patient still has no evidence of recurrence, the prognosis is poor for this group of patients.

[Rare case of retroperitoneal malignant Schwannoma]

Malignant Schwannoma, recently renamed malignant peripheral nerve sheat tumor retroperitoneally localized, represents 0.01 of retroperitoneal tumours. A 41-year old woman, without pathological record--and without cutaneous neurofibromatosis--hospitalized for increased volume of the abdomen, without symptomatology, is diagnosed after the imaging and biological tests--without CT and RMN--with retroperitoneal tumour. The unusual size of tumour--6000 gr.--the macroscopic aspect suggesting malignancy (histopathologically and immunohistochemically confirmed), the relatively easy extirpation which, nevertheless, required caudal spleen- and pancreatectomy as well as transvers colectomy, the absence of proximity adenopathy and remote secondary determinations, the simple postoperative evolution represent overwhelming elements in this case. Two years after the operation, during which the patient was under chemotherapy, on a routine control we found a relapse at a distance from the initial tumour (primitive tumour ?), totally operable. For the time being, after almost five years from the first operation, there are no clinical, biological and imaging changes.

CONCLUSIONS

the retroperitoneal space is quite enough for the development of large tumour masses, without symptomatology. The present case combines most characteristics of retroperitoneal neoplasms: large or very large size, quasi-absent symptomatology, difficulty in preoperative diagnosis, surgical tactics and techniques--quite often, the total extirpation of tumour mass led to the sacrifice of other organs within the limits of a justified risk--and unforeseeable evolution with relapses having the same characteristics.

Radiation-induced femoral arteritis

Radiation arteritis is currently an uncommon sequalae of external beam radiation, however because of the increasing use of radiotherapy in the management of neoplastic conditions its recognition is increasingly important. We present two cases of debilitating femoral occlusive disease, secondary to radiation exposure, at a long period post irradiation and review the pathophysiolgy and management options for this condition.

Intracranial subfrontal schwannoma treated with surgery and 3D conformal radiotherapy

Subfrontal schwannoma not arising from the cranial nerves are rare tumors. A 19-year-old man presented with a large subfrontal extra-axial enhancing mass with a preoperative diagnosis of skull base meningioma. A subtotal resection of the tumor mass was carried out. Microscopic examination revealed it to be a schwannoma. The residual tumor was treated with fractionated three-dimensional conformal radiotherapy (3D CRT). The rationale of treating with radiotherapy in such cases is analyzed.

Malignant Nerve Sheath Tumor of the Right Cerebral Peduncle: Case Report

OBJECTIVE AND IMPORTANCE

Schwannomas occurring in the neuraxis are very rare. Usually, these tumors are benign. Primary malignant intracerebral nerve sheath tumors are extremely rare, with only five documented cases in the international literature. We report one case of a primary malignant intracerebral nerve sheath tumor occurring in the right cerebral peduncle of a 35-year-old man.

CLINICAL PRESENTATION

Magnetic resonance imaging revealed a heterogeneous peripherally enhancing mass of the right cerebral peduncle, surrounded by a small edema.

INTERVENTION

Unlike the five cases previously reported, this is the first time a stereotactic biopsy has been performed, and this is the only patient who responded to cranial radiation therapy for approximately 2 years. When the tumor recurred, a systemic chemotherapy treatment was prescribed. No positive response was seen, and the patient died 29 months after the initial diagnosis.

CONCLUSION

An accurate diagnosis and planned aggressive treatment seem to be the key elements in the management of the disease.

Intra-cerebral schwannoma simulating glioma

An intra-cerebral schwannoma, presenting as a cystic, calcified, enhancing frontal mass, arising in a 52-year-old woman was misdiagnosed as a glioma and treated with radiotherapy. This observation emphasizes the importance of careful histological reexamination of all brain tumors when a discrepancy appears between the initial histological diagnosis and the clinical evolution, in order to recognize rare curable entities and to avoid potentially toxic treatment.

Superficial malignant schwannoma of the scalp

BACKGROUND

Malignant schwannoma is a rare sarcoma that is located mostly on trunk and extremities; the head and neck are unusual sites for its development. Almost half of these tumors arise from neurofibromas with or without von Recklinghousen's disease, and most of the remainder develop de novo from peripheral nerve trunks. Development in the superficial soft tissues is extremely rare.

OBJECTIVE

To present a case of superficial malignant schwannoma of the scalp, which is an uncommon presentation.

METHODS

An 80-year-old male patient presented with a painless ulceration on his scalp. The clinical and radiologic properties of the tumor were consistent with a skin tumor.

RESULTS

The lesion was excised, and reconstruction was achieved by transposition scalp flap. Malignant schwannoma was given as diagnosis by histopathologic examination with immunohistochemistry.

CONCLUSION

Malignant schwannomas may also occur in the skin. Clinically, these superficial forms closely resemble skin tumors, especially malignant melanoma. The treatment of choice in these tumors is wide resection combined with radiotherapy.

Feasibility of insertion/implantation of 2.0-mm-diameter gold internal fiducial markers for precise setup and real-time tumor tracking in radiotherapy

PURPOSE

To examine the feasibility and reliability of insertion of internal fiducial markers into various organs for precise setup and real-time tumor tracking in radiotherapy (RT).

MATERIALS AND METHODS

Equipment and techniques for the insertion of 2.0-mm-diameter gold markers into or near the tumor were developed for spinal/paraspinal lesions, prostate tumors, and liver and lung tumors. Three markers were used to adjust the center of the mass of the target volume to the planned position in spinal/paraspinal lesions and prostate tumors (the three-marker method). The feasibility of the marker insertion and the stability of the position of markers were tested using stopping rules in the clinical protocol (i.e., the procedure was abandoned if 2 of 3 or 3 of 6 patients experienced marker dropping or migration). After the evaluation of the feasibility, the stability of the marker positions was monitored in those patients who entered the dose-escalation study.

RESULTS

Each of the following was shown to be feasible: bronchoscopic insertion for the peripheral lung; image-guided transcutaneous insertion for the liver; cystoscopic and image-guided percutaneous insertion for the prostate; and surgical implantation for spinal/paraspinal lesions. Transcutaneous insertion of markers for spinal/paraspinal lesions and bronchoscopic insertion for central lung lesions were abandoned. Overall, marker implantation was successful and was used for real-time tumor tracking in RT in 90 (90%) of 100 lesions. No serious complications related to the marker insertion were noted for any of the 100 lesions. Using three markers surgically implanted into the vertebral bone, the mean +/- standard deviation in distance among the three markers was within 0.2 +/- 0.6 mm (range -1.4 to 0.8) through the treatment period of 30 days. The distance between the three markers gradually decreased during RT in five of six prostate cancers, consistent with a mean rate of volume regression of 9.3% (range 0.015-13%) in 10 days.

CONCLUSIONS

Internal 2.0-mm-diameter gold markers can be safely inserted into various organs for real-time tumor tracking in RT using the prescribed equipment and techniques. The three-marker method has been shown to be a useful technique for precise setup for spinal/paraspinal lesions and prostate tumors.

Calculation of rotational setup error using the real-time tracking radiation therapy (RTRT) system and its application to the treatment of spinal schwannoma

PURPOSE

The efficacy of a prototypic fluoroscopic real-time tracking radiation therapy (RTRT) system using three gold markers (2 mm in diameter) for estimating translational error, rotational setup error, and the dose to normal structures was tested in 5 patients with spinal schwannoma and a phantom.

METHODS AND MATERIALS

Translational error was calculated by comparing the actual position of the marker closest to the tumor to its planned position, and the rotational setup error was calculated using the three markers around the target. Theoretically, the actual coordinates can be adjusted to the planning coordinates by sequential rotation of gamma degrees around the z axis, beta degrees around the y axis, and alpha degrees around the x axis, in this order. We measured the accuracy of the rotational calculation using a phantom. Five patients with spinal schwannoma located at a minimum of 1-5 mm from the spinal cord were treated with RTRT. Three markers were inserted percutaneously into the paravertebral deep muscle in 3 patients and surgically into two consecutive vertebral bones in two other patients.

RESULTS

In the phantom study, the discrepancies between the actual and calculated rotational error were -0.1 +/- 0.5 degrees. The random error of rotation was 5.9, 4.6, and 3.1 degrees for alpha, beta, and gamma, respectively. The systematic error was 7.1, 6.6, and 3.0 degrees for alpha, beta, and gamma, respectively. The mean rotational setup error (0.2 +/- 2.2, -1.3 +/- 2.9, and -1.3 +/- 1.7 degrees for alpha, beta, and gamma, respectively) in 2 patients for whom surgical marker implantation was used was significantly smaller than that in 3 patients for whom percutaneous insertion was used (6.0 +/- 8.2, 2.7 +/- 5.9, and -2.1 +/- 4.6 degrees for alpha, beta, and gamma). Random translational setup error was significantly reduced by the RTRT setup (p < 0.0001). Systematic setup error was significantly reduced by the RTRT setup only in patients who received surgical implantation of the marker (p < 0.0001). The maximum dose to the spinal cord was estimated to be 40.6-50.3 Gy after consideration of the rotational setup error, vs. a planned maximum dose of 22.4-51.6 Gy.

CONCLUSION

The RTRT system employing three internal fiducial markers is useful to reduce translational setup error and to estimate the dose to the normal structures in consideration of the rotational setup error. Surgical implantation of the marker to the vertebral bone was shown to be sufficiently rigid for the calculation of the rotational setup error. Fractionated radiotherapy for spinal schwannoma using the RTRT system may well be an alternative or supplement to surgical treatment.

[Paralateral-nasal malignant schwannoma with rhabdomyoblastic differentiation (Triton tumor). Report of a case]

Malignant schwannoma with rhabdomyoblastic differentiation (Triton tumor) is a very rare variant of the malignant tumors arising in the peripheral nerve sheath. In 70% of the cases, the neoplasm is associated with Von Recklinghausen's neurofibromatosis; in the remaining 30% it is the sole morbid finding. Its biological behaviour is, in any case, more aggressive than that of simple malignant schwannoma; its course is rapid and its prognosis is dismal. Local recurrences are frequent, and distant metastases, preferentially situated in the lung and brain, are present in about 50% of the cases. Post-operative radiotherapy is always indicated. We report a case of a 64-year-old man who presented a right paralatero-nasal Triton tumor. Following exeresis, a cycle of high-dose radiotherapy was prescribed; the 10-year follow-up revealed no sign of recurrence or distant metastases.

Management of benign cranial nonacoustic schwannomas by fractionated stereotactic radiotherapy

Schwannomas are the most common tumors of cranial nerves. Nonacoustic schwannomas are very rare tumors, accounting for approximately 10% of intracranial schwannomas. Standard treatment is complete surgical resection if possible. The role of fractionated stereotactic radiotherapy remains to be defined. Thirteen patients with cranial nonacoustic schwannomas underwent fractionated stereotactic radiotherapy. Seven patients had trigeminal schwannomas, three schwannomas of the lower cranial nerves, and three located in the cerebellopontine angle without involvement of the acoustic nerve. Treatment included primary or adjuvant radiotherapy in progressive disease. Tumor volume ranged from 4.5 to 76.0 cc (median 19.8 cc). Median dose was 57.6 Gy with 1.8 Gy/fraction. Median follow-up was 33 months (range 13-70 months). Local tumor control rate was 100% (13/13). Tumor size remained stable in nine patients and decreased in four. Improvement of preexisting neurological deficits was seen in four cases. No patient developed new cranial nerve or brain stem deficits. No patient showed clinically significant complications of irradiation. Fractionated stereotactic radiotherapy is an effective and well-tolerated noninvasive treatment for cranial nonacoustic schwannomas with excellent tumor control rates. It is an option for patients at higher risk for microsurgical resection or in residual and recurrent tumors.

Radiotherapy and radiosurgery for skull base tumors

Tumors arising in the vicinity of the skull base are relatively uncommon; however, lesions that may be successfully treated by radiotherapy and radiosurgery include temporal bone chemodectomas, schwannomas, juvenile angiofibromas, pituitary adenomas, and meningiomas. This article reviews treatment techniques and results and discusses the pertinent literature.

Primary pigmented malignant schwannoma in the posterior mediastinum

This paper describes a rare case of primary pigmented malignant schwannoma arising from the sympathetic trunk in the posterior mediastinum. A 30-year-old woman underwent a thoracoscopic tumor extirpation. A primary pigmented malignant schwannoma was diagnosed histologically. The tumor presented fascicles and whorls of pigmented plump spindle cells and positive immunoreactivity to S-100 protein, vimentin, and HMB-45. Postoperative radiotherapy of the mediastinum was performed. Our case demonstrates the successful thoracoscopic resection and postoperative radiation treatment of a malignant schwannoma.

Correlation of intraoperatively irradiated volume and fibrosis in patients with soft-tissue sarcoma of the extremities

PURPOSE

To investigate the influence of intraoperatively irradiated volume on soft-tissue fibrosis.

METHODS AND MATERIALS

Fifty-three patients with soft-tissue sarcoma of the extremities were treated with intraoperative radiotherapy (IORT) (median dose 15 Gy) and postoperative fractionated therapy (median dose 46 Gy). The median follow-up was 41.5 months (range 18-94). Late toxicity was classified according to the LENT-SOMA criteria. A Cox regression model was calculated to identify the parameters that could influence soft-tissue fibrosis Grade 3 or 4. Five parameters were observed: extent of surgical procedure, IORT in case of recurrence, extent of IORT volume, extent of IORT dose, and extent of postoperative volume. In addition, a logistic regression model was calculated to demonstrate the relationship between the IORT volume and fibrosis development.

RESULTS

The overall survival rate after 5 years was 84%. The actuarial tumor control rate was 90% after 5 years. Eleven patients developed soft-tissue fibrosis. Five patients developed Grade 3 fibrosis and 1 patient developed Grade 4 fibrosis. Only the IORT volume had a significant influence on Grade 3 or 4 fibrosis development. An IORT volume of 210 cm(3) conveyed a 5% risk (confidence interval 1-20%) of the development of severe fibrosis. The risk of severe Grade 3 or 4 fibrosis increased to 50% (confidence interval 15-80%) if a volume of 420 cm(3) was irradiated.

CONCLUSION

The effect of volume in patients treated with IORT was remarkable. The ratio of side effects was relatively low. The risk of soft-tissue Grade 3 or 4 fibrosis increased with the extent of the IORT volume. Compared with the literature, IORT provides excellent local control in these patients.

Patient position reproducibility in fractionated stereotactically guided conformal radiotherapy using the BrainLab mask system

PURPOSE

Dedicated mask systems nowadays allow the use of stereotactic radiotherapy in fractionated regimes, therefore combining the advantages of high precision radiotherapy with the biological benefit of fractionation. Therefore the knowledge of institution specific isocenter accuracy is essential for decision-making about margins to be allowed to form the planning target volume.

PATIENTS AND METHOD

Measurements of isocenter deviations during fractionated treatments were performed in 33 patients using the simulator Simulix-xy (Oldelft) in connection with the BrainLab angiographic localizer-box as well as port-films. In both cases repeated images were overlaid by use of anatomical landmarks with a methodical accuracy in the order of 0.5 mm.

RESULTS

Both methods yield random isocenter deviations of less then 2 mm (standard deviation) in all three directions and no significant systematic deviations. These values are in the order of the accuracy of the method, obtained by comparison of two independent investigators, as well as they are comparable with the literature.

CONCLUSIONS

The accuracy of less than 2 mm indicates safety margins of 3-4 mm as sufficient for clinical routine to cover the target in 95.5% of all set-ups (2 SD).

Malignant schwannoma of the trigeminal nerve

SUMMARY

We present the MR imaging, CT, and clinical findings of a patient with malignant schwannoma of the trigeminal nerve. Local tumor recurrence is frequent and may be mistaken for lymphatic spread. In this report, we emphasize the natural history of this rare tumor and discuss the importance of imaging in diagnosis and surveillance.

[Malignant schwannoma of parotid gland. Case report and review of literature]

The authors described a rare malignant neoplasm of peripheral nerve sheath, sarcomatous neurillemoma, localized in parotid gland in 72-year female. Findings of the computer tomography, nuclear magnetic resonance and Doppler-ultrasound are presented and discussed. A review of world literature, including 14 cases of this tumor, was made.

[Fractionated radiotherapy of intracranial meningiomas and neurinomas]

In most institutions, surgical excision remains the standard treatment of meningiomas and neurinomas; the aim of surgery is complete resection. However, total removal is not always feasible without significant morbidity and in some cases, the patient's condition contraindicates surgery. For incompletely excised tumors, recurrences will have consequences on neurological functions. There are now many reports in the literature confirming the fact that radiotherapy significantly decreases the incidence of recurrence of incompletely resected benign tumors and that it can replace surgery in some situations where an operation would involve considerable danger or permanent neurological damage: about 80 to 90% of such tumors are controlled with fractionated radiotherapy. Stereotaxic and three-dimensional treatment planning techniques increase local control and central nervous system tolerance so that the respective place of surgery and radiotherapy needs to be redefined, considering efficacy and morbidity of these two therapeutic means. In this article, we limit our remarks to fractionated radiotherapy and, after a review of the literature, we discuss the indications, volume evaluations and the techniques currently used.

[Sarcomas of the vulva. Report of 2 cases]

We report two cases of vulvar sarcomas that are our Institutional experience in 29 years. The first case was a teenager of 14 years-old with a low grade leiomyosarcoma surgically treated. Along a 22 years follow-up the disease has had four local recurrences of more than 5 cm each one: two after surgery and two after surgery plus chemotherapy and surgery plus radiotherapy respectively. She is alive disease evidence after two years from the last combined treatment. The second one, was a 26 years-old patient with a malignant schwannoma of 12 cm in diameter treated with combined radical surgery, radiotherapy, and chemotherapy. She is alive and without disease evidence 52 months after surgery. We emphasized that these tumors are very rare and the fact that the first patient is the youngest and with more years of follow up according the bibliography consulted. Treatment of vulvar sarcomas is radical local excision followed mainly by radiotherapy with infiltrating margins. The value of postoperative adjuvant chemotherapy is uncertain. According to the natural history and behavior of vulvar sarcomas, we conclude that the elective treatment of these tumors should be carry out in institutions of high level.

Intensity modulation with the "step and shoot" technique using a commercial MLC: a planning study. Multileaf collimator

PURPOSE/OBJECTIVE

For complex planning situations where organs at risk (OAR) surrounding the target volume place stringent constraints, intensity-modulated treatments with photons provide a promising solution to improve tumor control and/or reduce side effects. One approach for the clinical implementation of intensity-modulated treatments is the use of a multileaf collimator (MLC) in the "step and shoot" mode, in which multiple subfields are superimposed for each beam direction to generate stratified intensity distributions with a discrete number of intensity levels. In this paper, we examine the interrelation between the number of intensity levels per beam for various numbers of beams, the conformity of the resulting dose distribution, and the treatment time on a commercial accelerator (Siemens Mevatron KD2) with built-in MLC.

METHODS AND MATERIALS

Two typical, clinically relevant cases of patients with head and neck tumors were selected for this study. Using the inverse planning technique, optimized treatment plans are generated for 3-25 evenly distributed coplanar beams as well as noncoplanar beams. An iterative gradient method is used to optimize a physical treatment objective that is based on the specified target dose and individual dose constraints assigned to each organ at risk (brain stem, eyes, optic nerves) by the radiation oncologist. The intensity distribution of each beam is discretized within the inverse planning program into three to infinitely many intensity levels or strata. These stratified intensity distributions are converted into MLC leaf position sequences, which can be subsequently transferred via computer link to the linac console, and can be delivered without user intervention. The quality of the plan is determined by comparing the values of the objective function, dose-volume histograms (DVHs), and isodose distributions.

RESULTS

Highly conformal dose distributions can be achieved with five intensity levels in each of seven beams. The merit of using more intensity levels or more beams is relatively small. Acceptable results are achievable even with three levels only. On average, the number of subfields per beam is about 2-2.5 times the number of intensity levels. The average treatment time per subfield is about 20 s. The total treatment time for the three-level and seven-beam case with a total of 39 subfields is 13 min.

CONCLUSION

Optimizing stratified intensity distributions in the inverse planning process allows us to achieve close to optimum results with a surprisingly small number of intensity levels. This finding may help to facilitate and accelerate the delivery of intensity-modulated treatments with the "step and shoot" technique.

[Malignant schwannoma of the neck]

Malignant schwannoma (MS) is a tumor of the peripheral nervous system, extremely rare when settled in head and neck. Conversely these two are preferable locations for benign schwannomata. We report a feminine patient, 74-year-old, with a right laterocervical massa, evolving in 3 months, surgically removed and postoperative radiotherapeutic treatment, which remains asymptomatic since one year and a half.

[Neurilemmoma of the nasal cavity and paranasal sinuses (report of 12 cases)]

OBJECTIVE

To further understand the neurilemmoma of nose.

METHOD

12 cases of neurilemmomas of the nasal cavity and paranasal sinuses were treated successfully by operation, 2 cases of malignant change lesions were treated by extensive resection and radiation.

RESULT

11 in 12 cases were followed up. 9 cases were cured and no any serious complications, 2 cases of malignant tumor were died.

CONCLUSION

Early stage diagnosis is important. CT scan should be made as essential examination, complete surgical resection is the choice of treatment for primary lesions; malignant change lesions should be treated by combined operation with radiation.

Hypofractionated radiation therapy of brain masses in dogs: a retrospective analysis of survival of 83 cases (1991-1996)

There are few reports of radiation treatment for brain tumors in dogs, and the optimal treatment protocol has yet to be established. We completed a retrospective analysis of the survival times of a series of 83 dogs with intracranial masses that were treated by hypofractionated megavoltage radiation therapy. A total tumor dose of 38 Gray was given over 5 weeks as once weekly fractions via 3 perpendicular portals. The median survival time from the start of radiotherapy for the whole cohort was 43.7 weeks (range, 0.1-172 weeks). Extra-axial masses had a better survival time (49.7 weeks) than did other intracranial masses (intra-axial, 40.4 weeks; pituitary, 21.0 weeks). Delayed radiation toxicity was suspected as the cause of death or reason for euthanasia in 12 dogs. The hypofractionated radiation protocol resulted in survival times similar to those obtained using more conventional multifractionated regimens, and this protocol may be a useful, less intensive alternative treatment for brain tumors in dogs.

[Fractionated irradiation of cerebellopontine angle neurinoma: 12 years' experience of the Bordeaux University Hospital Center]

PURPOSE

To evaluate retrospectively the long-term results of fractionated radiation therapy (RT) in cerebello-pontine angle neurinomas (CPA).

METHODS AND MATERIAL

From January 1986 to October 1995, 29 patients with stage III and IV neurinomas were treated with external fractionated RT. One patient was irradiated on both sides and indications for RT were as follows: (1) general contraindications for surgery (16 patients); (2) hearing preservation in bilateral neurinomas after controlateral tumor exeresis (six patients); (3) partial tumor removal (five patients); and, (4) non-surgical recurrence (three patients). A three to four fields technique with coplanar static beams and conformal cerobend blocks was used; doses were calculated on a 95 to 98% isodoses and were given five days a week for a median total dose of 51 Gy (1.8 Gy/fraction). Most patients were irradiated with 6 to 10 MV photons).

RESULTS

Median follow-up was 66 months (seven to 120 months). Seven patients died, two with progressive disease, five from non-tumoral causes. Tumor shrinkage was observed in 13 patients (43.3%), stable disease in 14 (46.6%), and tumor progression in three. Two patients underwent total tumor removal after RT (one stable and one growing tumor). Hearing was preserved in four out of six patients. No patient experienced facial or trigeminal neuropathy.

CONCLUSION

Fractionated RT is a well tolerated and efficacious treatment of large non-surgical CPA neurinomas.