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J C Flickinger

Publications and source records attributed to J C Flickinger.

At least 181 records · Page 10Linked to original sources
PubMed1990

Radiosurgery for acoustic neurinomas: early experience.

We reviewed our early experience with the first 26 patients with acoustic neurinomas (21 unilateral, 5 bilateral) treated by stereotactic radiosurgery using the first North American 201-source cobalt-60 gamma knife. Follow-up ranged from 6 to 19 months (median, 13 months). Serial postoperative imaging showed either a decrease in tumor size (11 patients) or growth arrest (15 patients). Loss of central contrast enhancement was a characteristic change (18 patients). Seven patients had good or serviceable hearing preoperatively. In all 7 the preoperative hearing status was retained immediately after radiosurgery. At follow-up, 3 had preserved hearing, 1 had reduced hearing, and 3 had lost all hearing in the treated ear. Hearing in 1 patient that was nonserviceable preoperatively later improved to a serviceable hearing level. Delayed facial paresis developed in 6 patients, and delayed trigeminal sensory loss developed in 7 patients, none of whom had significant deficits before radiosurgery. Both facial and trigeminal deficits tended to improve within 3 to 6 months of onset with excellent recovery anticipated. Lower cranial nerve dysfunction was not observed. All 26 patients remain at their preoperative employment or functional status. At present, stereotactic radiosurgery is an alternative treatment for acoustic neurinomas in patients who are elderly, have significant concomitant medical problems, have a tumor in their only hearing ear, have bilateral acoustic neurinomas, refuse microsurgical excision, or have recurrent tumor despite surgical resection. Although longer and more extensive follow-up is required, the control of tumor growth and the acceptable rate of complications in this early experience testifies to the future expanding role of this technique in the management of selected acoustic neurinomas.

Adolescent↗
PubMed1990

In vivo biological effects of stereotactic radiosurgery: a primate model.

Single-fraction, closed skull, small-volume irradiation (radiosurgery) of intact intracranial structures requires accurate knowledge of radiation tolerance. We have developed a baboon model to assess the in vivo destructive radiobiological effects of stereotactic radiosurgery. Three baboons received a single-fraction, 150-Gy lesion of the caudate nucleus, the thalamus, or the pons using the 8-mm diameter collimator of the gamma unit. Serial standard neurodiagnostic tests (neurological examination, computed tomographic scan, magnetic resonance imaging, stable xenon-enhanced computed tomographic scan of cerebral blood flow, somatosensory and brain stem evoked potentials, and myelin basic protein levels of cerebrospinal fluid) were compared with preoperative studies. Magnetic resonance imaging revealed the development of a lesion at the target site between 45 and 60 days after irradiation. Deterioration of the brain stem evoked potentials preceded imaging changes when the lesion encroached on auditory pathways. Myelin basic protein levels increased subsequent to imaging changes. Postmortem neuropathological examination confirmed a well-demarcated radionecrosis of the target volume. The baboon model appears to be an excellent method to study the in vivo biological effects of radiosurgery.

Animals↗
PubMed1990

Stereotactic radiosurgery of angiographically occult vascular malformations: indications and preliminary experience.

Stereotactic radiosurgery has been shown to treat successfully angiographically demonstrated arteriovenous malformations of the brain. Angiographic obliteration has represented cure and eliminated the risk of future hemorrhage. The role of radiosurgery in the treatment of angiographically occult vascular malformations (AOVMs) has been less well defined. In the initial 32 months of operation of the 201-source cobalt-60 gamma knife at the University of Pittsburgh, 24 patients meeting strict criteria for high-risk AOVMs were treated. Radiosurgery was used conservatively; each patient had sustained two or more hemorrhages and had a magnetic resonance imaging-defined AOVM located in a region of the brain where microsurgical removal was judged to pose an excessive risk. Venous angiomas were excluded by performance of high-resolution subtraction angiography in each patient. Fifteen malformations were in the medulla, pons, and/or mesencephalon, and 5 were located in the thalamus or basal ganglia. Follow-up ranged from 4 to 24 months. Nineteen patients either improved or remained clinically stable and did not hemorrhage again during the follow-up interval. One patient suffered another hemorrhage 7 months after radiosurgery. Five patients experienced temporary worsening of pre-existing neurological deficits that suggested delayed radiation injury. Magnetic resonance imaging demonstrated signal changes and edema surrounding the radiosurgical target. Dose-volume guidelines for avoiding complications were constructed. Our initial experience indicates that stereotactic radiosurgery can be performed safely in patients with small, well-circumscribed AOVMs located in deep, critical, or relatively inaccessible cerebral locations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Stereotactic gamma radiosurgery for intracranial vascular malformations and tumors: report of the initial North American experience in 331 patients.

We reviewed the initial experience with 331 consecutive patients treated during the first 2 years of operation of the University of Pittsburgh Gamma Unit. Among 178 patients with vascular malformations, 161 had angiographically demonstrable arteriovenous malformations, and 17 had angiographically occult malformations. Patients with tumors included 123 with histologically benign, predominantly extra-axial neoplasms and 30 with malignant, predominantly intra-axial neoplasms. When the arteriovenous malformation nidus could be covered with at least the 50% isodose line and a dose to the margin greater than or equal to 20 Gy, 60% were obliterated within 1 year. Patients with benign tumors and well-circumscribed malignant tumors did not experience tumor growth within the radiosurgical treatment volume. The role of radiosurgery is expanding to include primary treatment of larger lesions than was formerly possible and adjunctive treatment of more complex arteriovenous malformation and tumors.

Adolescent↗
PubMed1989

Incidence of cerebral infarction after radiotherapy for pituitary adenoma.

The incidence of cerebral infarction was studied in 156 patients irradiated for treatment of pituitary adenomas. Seven patients experienced strokes at intervals of 3.2 to 14.6 years after irradiation. The observed incidence was not significantly greater than the expected value of 3.5 strokes (P = 0.078). Six strokes occurred in patients receiving equivalent doses (ED) of 1070 ret or more (observed to expected ratio 3.87, significantly elevated; P less than 0.001). Univariate log-rank analysis showed that the risk of stroke was significantly higher (P = 0.010) in patients receiving an ED of 1070 ret or more (4180 cGy/22 fractions) than those receiving lower doses. Multivariate analysis, however, demonstrated that the increased risk of stroke was associated only with increasing age (P less than 0.0001), not ED (P = 0.148). Due to these inconsistent statistical results, no definitive conclusions could be reached about the relationship between radiation dose to the pituitary and subsequent cerebral infarction.

Adenoma↗
PubMed1989

Radiotherapy of nonfunctional adenomas of the pituitary gland. Results with long-term follow-up.

A total of 112 patients with the diagnosis of nonfunctional pituitary adenoma received radiation therapy at the University of Pittsburgh between 1964 and 1987. Postoperative radiation therapy was administered in 87 patients. Actuarial progression-free survival (tumor control) at 5, 10, 15, and 20 years was 97%, 89%, 87%, and 76%, respectively. Radiation prescribed to the 95% isodose ranged from 35.72 Gy to 62.32 Gy. Multivariate analysis showed decreased tumor control to be significantly associated with increasing field size (P = .036). No improvement in tumor control could be detected with increasing total radiation dose or nominal standard dose (NSD). One patient developed optic neuropathy and another developed a glioblastoma after doses in both patients of 4750 cGy in 25 fractions. External beam radiotherapy for nonfunctional pituitary adenomas was found to be effective and safe when doses less than 4750 cGy in 25 fractions were used.

Adenoma↗
PubMed1989

Prognostic factors in the diagnosis and treatment of primary central nervous system lymphoma.

The authors describe the results of multimodality therapy in 27 patients with biopsy-proven primary central nervous system (CNS) lymphoma treated between 1976 and 1986. Treatment included surgical resection (15 patients), radiotherapy (27 patients), and chemotherapy (nine patients). Actuarial survival rates for the 27 patients at 1, 2, and 5 years after diagnosis were 70%, 54%, and 45%, respectively. Nine patients were recurrence-free at 8 to 106 months follow-up. A multivariate risk analysis identified five factors which had a favorable impact on survival: (1) age less than 60 years (P less than 0.02); (2) preoperative Karnofsky performance score greater than or equal to 70 (P less than 0.02); (3) presence of strictly hemispheric tumor (P less than 0.0003); (4) whole-brain radiation dose between 4000 and 5000 cGy (P less than 0.05); and (5) addition of chemotherapy to radiotherapy (P less than 0.002). Patients with complete tumor resolution on computed tomography 6 months after beginning treatment also had longer survival (P less than 0.01). The presence of malignant cells on cerebrospinal fluid cytologic examination correlated with an increased risk of distant metastasis (P less than 0.05). In those patients whose disease eventually recurred, the administration of an additional therapeutic modality significantly increased the length of postrecurrence survival (P less than 0.05). Although surgical resection provided no increase in survival, the addition of chemotherapy to postoperative cranial irradiation significantly enhanced the duration of survival. Our experience suggests that pretreatment clinical and diagnostic factors can help in predicting survival and in planning treatment.

Adult↗
PubMed1989

Manual reconstruction of tumor volumes from CT scans for radiotherapy planning.

Using a computed tomographic scan to construct a tumor volume on a simulation film has become an important part of radiation therapy treatment planning. Techniques for reconstruction of brain tumor volumes from computed tomographic scans onto simulation films are discussed. A technique for reconstructing by hand the tumor volume projection at a different angle from the plane of the computed tomographic scan is outlined. Ignoring beam divergence simplifies reconstruction, allowing it to be done by hand but introduces an additional error of at most 0.06, 0.15, 0.26 and 0.42 cm for tumors with maximum diameters of 5, 7.5, 10 and 12.5 cm, respectively. This technique provides the capability for limited 3-dimensional volume reconstruction of small tumors without the use of the computer.

Brain↗
PubMed1989

An integrated logistic formula for prediction of complications from radiosurgery.

An integrated logistic model for predicting the probability of complications when small volumes of tissue receive an inhomogeneous radiation dose is described. This model can be used with either an exponential or linear quadratic correction for dose per fraction and time. Both the exponential and linear quadratic versions of this integrated logistic formula provide reasonable estimates of the tolerance of brain to radiosurgical dose distributions where there are small volumes of brain receiving high radiation doses and larger volumes receiving lower doses. This makes it possible to predict the probability of complications from stereotactic radiosurgery, as well as combinations of fractionated large volume irradiation with a radiosurgical boost. Complication probabilities predicted for single fraction radiosurgery with the Leksell Gamma Unit using 4, 8, 14, and 18 mm diameter collimators as well as for whole brain irradiation combined with a radiosurgical boost are presented. The exponential and linear quadratic versions of the integrated logistic formula provide useful methods of calculating the probability of complications from radiosurgical treatment.

Adult↗
PubMed1989

Repeat megavoltage irradiation of pituitary and suprasellar tumors.

From 1965 to 1984, ten patients with suprasellar or pituitary tumors received repeat courses of radiation therapy at the Joint Radiation Oncology Center of the University of Pittsburgh. The radiation doses varied between 36.00 to 53.65 Gy for the first treatment course and from 35.00 to 49.60 Gy for retreatment. Six patients were treated for pituitary tumors, two for germinoma, one for optic glioma, and one for craniopharyngioma. One died of disease progression 19 years after a second course of radiation. Two patients were dead of intercurrent disease 0.2 and 1.5 years after repeat radiation. The remainder are free of disease progression 1.6 to 20.5 years after repeat irradiation. Optic neuropathy developed in one patient 1.3 years following a second course of treatment to 40 Gy in 20 fractions administered 7.5 years after initial treatment to 46 Gy in 23 fractions. Neither the Nominal Standard Dose nor the Neuret formula provided an adequate estimate of the repair of radiation. An estimation that 40% of the original radiation dose effect is still present appears to be a reasonable "rule of thumb" guideline to account for prior radiotherapy.

Adolescent↗
PubMed1989

Gamma knife radiosurgery for intracranial arteriovenous malformations in childhood and adolescence.

Eighteen children or adolescents with intracranial arteriovenous malformations (AVM) underwent stereotactic radiosurgery using the first North American gamma knife. This closed-skull, single-treatment therapy, utilizing 201 ionizing beams of gamma-irradiation, was used as an alternative to microsurgical removal in these selected patients (aged 34 months to 18 years, mean 12.3 years) beginning in August 1987. No significant perioperative morbidity occurred, and no patient rebled or died in the follow-up interval ranging between 7 and 19 months. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to monitor the response to treatment and to determine when postoperative angiography was indicated. Of seven AVMs examined with cerebral angiography 1 year after treatment, three were completely obliterated; three others were significantly smaller, and their complete obliteration is anticipated by 2 years after treatment. Follow-up CT or MRI confirmed attenuation or signal changes suggestive of edema surrounding the treatment volume in 3 patients; 1 had transient worsening of a preexisting neurological deficit. Although a more long-term perspective is still required for this new technology now available in the United States, we believe that gamma knife stereotactic radiosurgery is a safe and effective method to obliterate AVM deemed too risky for microsurgical removal.

Adolescent↗
PubMed1988

The gamma knife.

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Brain Neoplasms↗
PubMed1988

Management of low-grade gliomas of the optic nerve and chiasm.

Thirty-six patients were evaluated between 1965 and 1983 for glioma of the optic nerves and/or chiasm. Median follow-up was 10.2 years. Pathologic verification was obtained in 32 patients. Tumor initially confined to the optic nerve recurred in one of five patients after complete resection. The actuarial survival for 25 patients irradiated for biopsy-proven glioma of the optic chiasm was 96%, 90%, and 90% at 5, 10, and 15 years, respectively, and the progression-free survival was 87% at 5, 10, and 15 years. Vision stabilized or improved in 86% of patients after radiotherapy. Patients irradiated to a dose greater than a NSD of 1385 ret had a significantly improved progression-free survival (P = 0.015). One serious complication occurred after a dose of 1533 ret. The recommended radiation dose for optic glioma is 45 to 50 Gy with 1.8 Gy fractions.

Adolescent↗
PubMed1988

Split course radiation therapy for adenocarcinoma of the pancreas.

Ninety-five patients with biopsy proven adenocarcinoma of the pancreas were treated with split course radiation therapy. Fifty-five patients had disease confined to the peripancreatic tissues and lymph nodes. Forty patients had metastatic disease. The intended radiation therapy scheduled consisted of two courses of 25 Gy in 10 fractions each followed by a 3 to 4 week rest period. Depending on the response and the patient's clinical status, another 10 Gy in 5 fractions was administered as a final boost. The median survival in patients with metastatic disease was 3 months and the median survival in patients with localized disease was 8 months. Twenty-seven of the fifty-five patients with localized disease received chemotherapy (5 FU or FAM) combined with radiotherapy. There was no significant difference in median survival between the patients treated with radiation alone and those with combined radiation and chemotherapy. The median survival for patients with localized disease receiving 25, 50, and 60 Gy were 3, 7, and 12 months respectively. After a dose of 50 Gy in 20 fractions, CT scan showed no evidence of tumor in 6%, smaller tumor size in 31%, stable tumor size in 41%, and tumor growth in 22% of patients. The split course radiation therapy was well tolerated and no late complications were detected. The medical and economic advantages of using split course radiation therapy and in using CT scan response to plan boost therapy are discussed.

Adenocarcinoma↗
PubMedDate not supplied

Radiosurgery for recurrent cranial base cancer arising from the head and neck.

BACKGROUND: Treatment options for head and neck cancers that recur at the cranial base are limited. METHODS: Twelve patients with head and neck cancers recurrent after resection and fractionated radiotherapy (n = 11) at the cranial base had stereotactic radiosurgery using the gamma unit. The median dose to the tumor margin was 16 Gy. Imaging follow-up varied from 3 to 17 months; the longest clinical follow-up was at 35 months. RESULTS: Three of 8 tumors studied by postradiosurgery imaging remained unchanged in size, 3 decreased, and 2 were no longer visible. There was no morbidity or worsening of symptoms after radiosurgery. Four patients died between 4 and 8 months and did not have postradiosurgery imaging performed. Mean survival after radiosurgery was 10.5 months, with 7 patients (58%) still living. CONCLUSIONS: Radiosurgery proved safe and effective in providing local control for recurrent cranial base cancers arising from the extracranial head and neck. Radiosurgery should be considered for those patients who have failed prior fractionated radiation or surgical resection, those who have tumors in high-risk cranial locations, or those who are poor medical candidates. Although this study shows its potential adjuvant role, longer follow-up and increased clinical experience will be necessary to evaluate the overall role of radiosurgery in head and neck cancer.

Adult↗
PubMedDate not supplied

Stereotactic radiosurgery in children and adolescents.

Stereotactic radiosurgery has had an increasing role in the treatment of selected intracranial lesions in pediatric patients. In our first 44 months experience, 60 of the patients (9%) treated were less than or equal to 18 years of age. Current indications for radiosurgery include primary treatment of high-risk arteriovenous malformations or acoustic neurinomas (usually in patients with neurofibromatosis), adjuvant treatment for recurrent benign tumors after surgery, or as adjuvant treatment to fractionated irradiation for malignant tumors.

Adolescent↗