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G Kantor

Publications and source records attributed to G Kantor.

At least 19 recordsLinked to original sources
PubMed2006

[Helical tomotherapy: general methodology for clinical and dosimetric evaluation (national French project)].

The methodology and choice of criteria and indexes used for a common evaluation of helical tomotherapy by 3 French centres are described. After a selection of clinical indications and definition of the general purpose are successively described the criteria and index selected for: 1) description of volumes and adaptation for on board imaging; 2) dose prescription and constraints related to IMRT; 3) intercomparaison of volumes and doses and potential dosimetric gain with this new equipment.

France↗
PubMed2006

[Conservative and functional management for soft tissue sarcomas of the extremities: role of radiotherapy].

Recent publications have permitted to quantify the benefit of radiotherapy in the conservative treatment of soft tissue sarcoma of the limbs. The aim of this review is to focus on aspects of radiotherapy witch influence local control and functional outcome for early and late normal tissue damage. The evaluation of late effects is performed according to Soma-Lent (Subjective-Objective-Management-Analytic-Late Effects of Normal Tissues) classification. About complications, neurological complications are probably under estimated and are related to total dose of radiation therapy.

Arm↗
PubMed2006

Prospective evaluation of quality of surgery in soft tissue sarcoma.

BACKGROUND: Prospective application of the French Sarcoma Group (FSG) method of surgery reporting in soft tissue sarcoma (STS) in a single centre. METHODS: Patients with primary STS of the extremities or trunk wall consecutively operated at the same institution from January 1996 to December 2002 were evaluated for local recurrence (LR). There were 205 patients, with AJCC/UICC stages III and IV in 51% of cases. Resection types according to FSG were R0 in 147, R1 in 53 and R2 in five cases. Radiotherapy was delivered in 163 patients and chemotherapy in 103. Multivariate analysis was performed. Overall five-year survival was 75%. Median follow-up for surviving patients was 53 months. RESULTS: Actuarial five-year LR incidence was 13% in 200 patients with gross resection (R0+R1), it was 7% in R0 and 30% in R1 patients (p<0.0001). At univariate analysis, significant prognosticators for LR were age, histotype, tumour invasion, grade and resection type R. At multivariate analysis, resection R1 (relative risk (RR) 4.3, p=0.001) and grade 3 (RR 3.9, p=0.013) independently predicted LR. Combining these two variables produced three prognostic groups for LR: group 0 (no factor, n=70), group 1 (one factor, n=94) and group 2 (two factors, n=36) with five-year LR of 4%, 12% and 39%, respectively (p=6.4x10(-7)). CONCLUSION: This first prospective evaluation of surgery reporting in STS evidences a fourfold, highly discriminating difference in LR between resections R0 and R1.

Adolescent↗
PubMed2005

[Radiation oncology training in France: demography, analysis of motivations of the young specialists, evaluation of the training].

During the 5 past national courses organised by the French society of radiation oncology (SFRO), three different types of survey were performed to analyse demography, motivations and quality of training of the young specialists. During the 5 past years, 50 radiation oncologists were training for the whole country (about 15 per year were graduated). A recent increase the number of young specialists is observed with a total number of 50 in 2000 to 75 in 2005. Nevertheless, the number of young specialists is dramatically insufficient and exposes for the future to an important demographic crisis. Analysis of motivations of choice for radiation oncology confirms the influence of a practical stage of oncology during the second cycle of the medical studies for 60% of the young specialists. Analysis of practical and theoretical training was performed according to the point of view and living experiences of the students. On the other hand, informations from teachers were less complete. Some needs are emphased as: 1) the quality of the follow during the training (importance of the recent implementation of a logbook); 2) importance of theoretical and practical training at the radiotherapy department; 3) help and incentive for research and scientific publication.

Demography↗
PubMed2005

[Radiation therapy of benign diseases. What's new eight years after?].

The authors present an update version of the indications for radiotherapy in the management of benign diseases. This is based on available randomized trials and recent international meetings. Validated indications remain the prevention of resected heterotopic bone ossifications, keloïds scars and pterygium and also treatment of arteriovenous malformations; the place of radiotherapy for malignant exophtalmia is more and more restricted. Randomized trials have demonstrated the efficacy of endobrachytherapy in the prevention of restenosis after angioplasty but the use of embedded stent has replaced this indication. Macular degeneration is no more an indication of radiotherapy. Quality requirements for radiotherapy are identical for benign or malignant indications.

Arteriovenous Malformations↗
PubMed2005

[Adjuvant radiation therapy for soft tissue sarcoma of the extremities: analysis of local control according to volume and dose].

PURPOSE: To evaluate retrospectively the anatomical definition of target volumes in the treatment of soft tissue sarcomas of the limbs and to study the radiation dose in the local control and toxicity. METHODS AND PATIENTS: Seventy-seven patients were consecutively treated for primary soft tissue sarcoma of the extremity with limb sparing surgery and external beam radiotherapy (EBRT) in the same institution. The median follow up was 56 months (17-89 months). RESULTS: Fifty-two patients (67%) had clear microscopic surgical margin (R0 resection), 23 (30%) had histologically positive microscopic margin (R1 resection), 2 had a macroscopic residual disease (R2 resection). An anatomical definition of target volumes has been realised. The mean dose was 50 Gy in 25 or 28 fractions; 23 patients received a boost restricted to the tumor bed: 13 with EBRT, 10 with brachytherapy (BRT). Thirty-four patients had an adjuvant chemotherapy. The overall 5 year local relapse rate was 10%. Seven local relapses were described, five of the high-grade tumours, and five in patients with positive margin. In univariate analysis, quality of surgery shows a significant effect for local control. By using LENT-SOMA scale for late toxicity, a significant difference was found for neurological complications for patients receiving a boost. CONCLUSIONS: The results of the series validate the concept of anatomical definition of the initial target volume. A boost should be realised for positive margin tumors and may be for high-grade tumors. Neurological toxicity must be considered for the evaluation of the prescribed dose.

Chemotherapy, Adjuvant↗
PubMed2005

[Analysis of target volumes for gliomas].

Gliomas are the most frequent tumors of the central nervous system of the adult. These intraparenchymal tumors are infiltrative and the most important criterion for definition of GTV and CTV is the extent of infiltration. Delineation of GTV and CTV for untreated and resected glioma remains a controversial and difficult issue because of the discrepancy between real tumor invasion and that estimated by CT or MRI. Is particularly helpful a joint analysis of the four different methods as histopathological correlations with CT and MRI, use of new modality imaging, pattern of relapses after treatment and interobserver studies. The presence of isolated tumor cells in intact brain, oedema or adjacent structures requires the definition of two different options for CTV: i) a geometrical option with GTV defined as the tumor mass revealed by the contrast-enhanced zone on CT or MRI and a CTV with an expanded margin of 2 or 3 cm; ii) an anatomic option including the entire zone of oedema or isolated tumor cell infiltration extending at least as far as the limits of the hyperintense zone on T2-weighted MRI. Inclusion of adjacent structures (such as white matter, corpus callosum, subarachnoid spaces) in the CTV mainly depends on the site of the tumor and size of the volume is generally enlarged.

Brain Neoplasms↗
PubMed2004

[Comparison of intensity-modulated postoperative radiotherapy with conventional postoperative conformal radiotherapy for retroperitoneal sarcoma].

External postoperative radiation therapy for retroperitoneal sarcoma is an example of treatment using large fields for complex shaped volumes of irradiation. Prescribed dose is limited by tolerance of adjacent organs at risk (OAR). From a recent case treated by conventional conformal radiotherapy (3D-CRT), we evaluate the benefit of five theoretical IMRT plans. Criteria used are calculated from DVH related to delineated PTV and OAR. IMRT should permit to enhance the prescribed dose without increasing dose in the OAR (especially residual kidney, spinal cord and small bowel). This theoretical study show the feasibility of a dose escalation from a treatment dose of 45 Gy delivered by 3D-CRT up to a planning dose of 54 Gy calculated by IMRT with: for the PTV: an improvement of the dose homogeneity about 5% (range 2-6%) and moreover the coverage factor (CF) about 13% (range 9-16%); for the OAR: an improvement of the protection factor (PF) about 20% (range 11-24%); and thus an improved conformity index (CI = CF x PF) about 25% (range 15-32%).

Feasibility Studies↗
PubMed2004

[Management of soft tissue sarcomas in first isolated local recurrence: a retrospective study of 83 cases].

PURPOSE: To analyse the management and clinical outcome of patients treated for a first isolated local recurrence of soft tissue sarcoma (trunk or extremities) and to identify prognosis factors. PATIENTS AND MATERIAL: This is a retrospective study of 83 adult patients treated between 1980 and 1999. Mean tumor size was 6 cm. Most sarcomas were located in extremities (N =74), were deep (N =60), and proximal (N =53). Thirty involved nerves or vessels. Histologic subtypes were mainly grade 2 (42%) or 3 (36%) histocytofibrosarcomas (49%) and liposarcomas (20%). Surgical treatment of recurrences consisted in wide excision (32 cases), marginal resection (46 cases), five patients requiring amputation. Final results were R0 (N =33), R1 (N =47) or R2 (N =3) resection. Beside surgery, six patients received neoadjuvant and seven others adjuvant chemotherapy. Twenty-three patients received postoperative external beam radiotherapy (EBRT) (mean dose 55 Gy) and 26 interstitial (192)Ir low dose rate brachytherapy (BCT) (mean dose 45 Gy for BCT alone, 22 Gy when associated with EBRT), 19 patients being re-irradiated. RESULTS: Mean follow up was 59 months. Thirty-seven (45%) tumors relapsed, 62% locally as first event. Nineteen patients developed secondary distant metastases. Multivariate analysis showed only tumour depth (P =0.05) and re-resection for primary R1 resection for the recurrence (P =0.018) being independent prognosis factors for tumour control, radiotherapy (EBRT and/or BCT) being significant in univariate analysis (P =0.05). Overall survival rate was 73, 54, and 47% at respectively 3, 5 and 10 years, and was 65, 35 and 32% after a further local recurrence. Multivariate analysis showed trunk (P =0.0001) or inferior extremity locations (P =0.023), symptomatic (P =0.001), high grade (P =0.01), deep (P = 0.01) tumours, and the occurrence of a further local failure (P =0.004) as unfavourable characteristics for overall survival. CONCLUSION: Because of the high relapse rate in this series, a first isolated local recurrence of STS increases mainly the risk of a subsequent local relapse. Quality of local treatment for the first local relapse is decisive. When a conservative treatment is feasible, it should combine surgical resection and radiotherapy, brachytherapy being the best suited in previously irradiated patients. Efforts have to be pursued to increase quality of the treatment of primary tumours, at best performed in centers that have expertise in this field.

Adult↗
PubMed2002

[Target-volume contours in radiotherapy. General principles].

Target volume delineation remains an important medical step for conformal radiotherapy. In this general presentation are discussed: the main difficulties for evaluation of gross tumor (GTV) and clinical target volume (CTV), the main recommendations for representation according to ICRU 62 report, differences observed during inter-observer volume comparisons.

Humans↗
PubMed2001

Prognostic factors in retroperitoneal sarcoma: a multivariate analysis of a series of 165 patients of the French Cancer Center Federation Sarcoma Group.

BACKGROUND: Surgery is the main prognostic factor in retroperitoneal sarcoma. However, despite progress, surgery alone is rarely curative, and analysis of the causes of failures and of other prognostic factors are warranted to ascertain treatment orientations. METHODS: Data of patients treated from 1.80 to 12.94 for primary retroperitoneal sarcoma were extracted from the French Federation of Cancer Centers Sarcoma Group registry. Univariate and multivariate analysis were performed for initial local control and for local and general outcome. One hundred sixty-five patients (median age, 54 years; range, 16--82 years) were identified. Median tumor size was 15 cm (range, 2--70 cm); 31% of tumors presented with neurovascular or bone involvement. Liposarcoma, leiomyosarcoma, and malignant fibrous histiocytoma represented 66% of the tumors. Eighty-four percent of the tumors were of high or intermediate grade. Twenty patients had initial metastases. Multimodality treatment included surgery (150 patients), radiotherapy (92 patients), and chemotherapy (77 patients). Complete excision was achieved in 94 of 145 nonmetastatic patients. Median follow-up was 47 months (range, 3--160 months). RESULTS: Actuarial overall 5-year survival rate (median) was 46% (51 months). The main prognostic factors for survival were initial metastases and surgery, which represented the major treatment-linked factor. High-grade of tumors affected local recurrence, metastatic recurrence, and survival. Adjuvant radiotherapy was significantly associated with reduced local recurrence. Various evolutive patterns were observed with histologic subtypes. CONCLUSIONS: Aggressive surgery remains mandatory in retroperitoneal sarcoma, but a randomized trial is needed to evaluate the place of radiotherapy for local control.

Adolescent↗
PubMed2001

[Gross tumor volume (GTV) and clinical target volume (CTV) in adult gliomas].

Glioblastoma multiform and astrocytoma are the most frequent primary cancer of the central nervous system of adult. Definitions of gross tumor volume (GTV) and clinical target volume (CTV) are based on the confrontation of clinical presentation (age, performance status, neurologic symptoms...), histological type and imaging aspects. For glioblastoma multiform, the GTV can be defined by the area of contrast enhancement observed on the CT scan or MRI. Definition of the CTV can be more difficult and have to take into account the risk of presence of isolated malignant cells in the oedema surrounding the tumor or in the adjacent brain structures. The classical concept of GTV plus a safety margin of 2 cm around is discussed with a CTV containing at least all the oedematous area and eventually adjacent brain structures (nuclei, corpus callosum or other long associative fibers...). For low grade astrocytoma, the definition of GTV can be difficult if the tumoral infiltration is diffuse without nodular visible tumor. CTV corresponds to at least T2 MRI hypersignal area when visible. For postoperative tumor, technical considerations are important for the detection of residual tumor. A safety margin around the resected area is designed according to the risk of presence of isolated cells or involvement of adjacent brain structures.

Astrocytoma↗
PubMed2001

[Definitions of target volumes in soft tissue sarcomas of the extremities].

Soft tissue sarcomas of the extremities are currently treated with more conservative and functional approaches, combining surgery, radiotherapy and chemotherapy. The role of external beam radiotherapy and brachytherapy has been defined through randomised studies performed in the 80's and 90's. However, the ubiquity of tumour location for these tumours makes difficult a systematic definition of local treatments. Tumour volume definition is based on pre and post surgical imaging (MRI) and on described pathological report. The clinical target volume will take into account quality of the resection and anatomical barriers and will be based on an anatomy and not only on safety margins around the tumour bed. General rules for this irradiation (doses, volumes) and principal results will be presented.

Brachytherapy↗
PubMed2001

[Postoperative morbidity and mortality after microsurgical exclusion of cerebral arteriovenous malformations. Current data and analysis of recent literature].

BACKGROUND AND PURPOSE: Microsurgical exclusion of a cerebral arteriovenous malformation (AVM) can compare favorably with radiosurgery. We sought to assess its rate of morbidity-mortality as it is presently reported in the literature, and to discuss some of its current and worthwhile indications. METHODS: Through Medline and additional searches by hand, we retrieved studies reporting the clinical and angiographic results after microsurgical excision of an AVM published between january 1990 and december 2000. RESULTS: a) Postoperative mortality was 3.3% (68/2 452 patients from 25 studies). Permanent postoperative morbidity was 8.6%. Morbidity was never absent varying from 1.5% to 18,7%. The morbidity-mortality rate increased with an increasing Spetzler-Martin's grade, and was related to the location of the AVM. A 4.6% morbidity (from 1.5% to 9.7%) and a zero mortality were reported after microsurgical removal of small lesions of less than 3 cm in diameter. b) Postoperative angiography confirmed a total excision of the AVM in 97% of the cases (1 050/1 076 patients over 11 series), varying from 91% to 100%. c) Permanent morbidity related to pre-surgical embolization varied from 4% to 8.9%. Results from multiple or combined treatment including microsurgery could not be summed up. CONCLUSIONS: A complete and definitive microsurgical excision of an AVM can be achieved with a high success rate and a low morbidity-mortality rate, according to sound indications and to the neurosurgeon's personal experience. The choice for a best treatment of an AVM is no longer limited to microsurgery; it is a team decision where the neurosurgeon plays a determining role.

Adult↗
PubMed2000

Low-dose-rate intraoperative brachytherapy combined with external beam irradiation in the conservative treatment of soft tissue sarcoma.

PURPOSE: Conservative treatment of soft tissue sarcomas most often implies combination of surgical resection and irradiation. The aim of this study was to evaluate low-dose-rate intraoperative brachytherapy, delivered as a boost, in the local control of primary tumors, with special concern about treatment complications. METHODS AND MATERIALS: Between 1986 and 1995, 112 patients underwent intraoperative implant. This report focuses on the group of 58 patients with primary sarcomas treated by combination of conservative surgery, intraoperative brachytherapy, and external irradiation. Most of the tumors were located in the lower limbs (46/58-79%). Median size of the tumor was 10 cm, most of the lesions being T2-T3 (51/58-88%), Grade 2 or 3 (48/58-83%). The mean brachytherapy dose was 20 Gy and external beam irradiation dose 45 Gy. In 36/58 cases, iridium wires had to be placed on contact with neurovascular structures. RESULTS: With a median follow-up of 54 months, the 5-year actuarial survival was 64.9%, with a 5-year actuarial local control of 89%. Of the 6 patients with local relapse, 3 were salvaged. Acute side effects, essentially wound healing problems, occurred in 20/58 patients, late side effects in 16/58 patients (7 neuropathies G2 to G4). No amputation was required. The only significant factor correlated with early side effects was the location of the tumor in the lower limb (p = 0.003), and with late side effects the vicinity of the tumor with neurovascular structures (p = 0.009). CONCLUSION: Brachytherapy allows early delivery of a boost dose in a reduced volume of tissue, precisely mapped by the intraoperative procedure. Combined with external beam irradiation, it is a safe and efficient treatment technique leading to high local control rates and limited functional impairment.

Adolescent↗
PubMed2000

[The role of surgery in the treatment of glial tumors].

Indications for surgery in the management of glial tumors is twofold. Surgery provides a pathology-based diagnosis that is mandatory in every patient with a clinical diagnosis of glial tumor. However, its role in duration of survival is controversial. Total surgical removal is the best prognostic factor in grade 1 glioma. For grade 2 to 4 gliomas, the results of surgery are variable. Surgical resection is undoubtedly associated with clinical improvement. Its impact on duration of survival is not firmly established, due to, on the one hand, the infiltrative pattern of these types of tumors and, on the other hand, to the inherent difficulty in evaluating their size either pre- or postoperatively. However, the sole clinical improvement related to surgical resection appears sufficient to justify patients' exposure to resective surgery. The surgical risk has dramatically decreased over the last few years mainly due to technical improvements.

Brain Neoplasms↗
PubMed1999

Prognostic factors in superficial adult soft tissue sarcomas: analysis of a series of 105 patients.

BACKGROUND AND OBJECTIVES: This study was undertaken to study the behavior of superficial soft tissue sarcomas (STS) and determine the factors related to prognosis. METHODS: The clinical records of 105 adults (56 men, 49 women, mean age: 56.4 years) were retrospectively analyzed. Univariate analysis was performed on the entire group for overall survival (OS), and metastasis-free survival (MFS). Local recurrence-free survival (LRFS) was studied only on patients first treated in our institute. RESULTS: With a median follow-up of 111.9 months, 66 (62.9%) patients were alive; 25 (23.8%) had died of their disease. For the entire series, 10-year OS and MFS were 62.5% and 71.9% respectively. For fifty-two patients treated for their sarcoma at the Institution since the first tumor occurrence event, 10-year LRFS was 80%. Tumor grade was the only factor correlated with OS and MFS, while tumor size was the main factor correlated with LRFS. CONCLUSION: Tumor size affects local control in STS while tumor grade is correlated with OS and MFS.

Adolescent↗