B. Henriques de Figueiredo

Tomothérapie hélicoïdale : aspects techniques et applications cliniques

Helical tomotherapy is an innovative device combining with the same linac on board-imaging and IMRT facilities. The first national French evaluations, supported by National Institut of Cancer (INCa) are presented. Dosimetric characteristics as quality of homogeneity, cut-off outside target volumes allow IMRT treatments for large and complex volumes and a good organ at risk sparing. First comparative dosimetric studies are discussed.

Dose de tolérance à l’irradiation des tissus sains : l’os chez l’adulte

Radiation tolerance for bone tissue has been mostly evaluated with regard to bone fracture. Main circumstances are mandibula osteoradionecrosis, hip and costal fracture, and patent or radiologic fractures in the treated volume. After radiation therapy of bone metastasis, the analysis of related radiation fracture is difficult to individualize from a pathologic fracture. Frequency of clinical fracture is less than 5% in the large series or cohorts and is probably underevaluated for the asymptomatic lesions. Women older than 50 years and with osteoporosis are probably the main population at risk. Dose-effect relations are difficult to qualify in older series. Recent models evaluating radiations toxicity on diaphysa suggest an important risk after 60 Gy, for high dose-fraction and for a large volume.

Mise au pointDose de tolérance à l’irradiation des tissus sains : l’os chez l’adulteNormal tissue tolerance to external beam radiation therapy: Adult bone☆

Radiation tolerance for bone tissue has been mostly evaluated with regard to bone fracture. Main circumstances are mandibula osteoradionecrosis, hip and costal fracture, and patent or radiologic fractures in the treated volume. After radiation therapy of bone metastasis, the analysis of related radiation fracture is difficult to individualize from a pathologic fracture. Frequency of clinical fracture is less than 5% in the large series or cohorts and is probably underevaluated for the asymptomatic lesions. Women older than 50 years and with osteoporosis are probably the main population at risk. Dose-effect relations are difficult to qualify in older series. Recent models evaluating radiations toxicity on diaphysa suggest an important risk after 60 Gy, for high dose-fraction and for a large volume.

Local treatment of metastases from differentiated thyroid cancer

OBJECTIVES To study the various local treatments available for thyroid cancer metastases, investigate techniques and assess their advantages and limitations and roles in the overall treatment strategy for metastatic disease. RESULTS We investigated metastases surgery, external radiation therapy, embolization, chemoembolization, cementoplasty, radiofrequency ablation and cryotherapy, describing techniques, advantages and drawbacks and possible complications. Indications were reviewed according to metastases location, and the roles of the various techniques are discussed in the overall treatment strategy for thyroid cancer metastases. Despite the advent of new targeted therapies, local treatment still has an important role to play: either palliative or, in oligometastatic involvement, curative. Even in extensive disease, it may allow postponement of tyrosine kinase inhibitor therapy, which, once initiated, has to be continued life-long, is expensive and is not free of side-effects.

Expérience de l’institut Bergonié à propos de 14 cas de tomothérapie hélicoïdale de tumeurs axiales et para-axiales

PURPOSE To evaluate the feasibility of helical tomotherapy intensity-modulated radiotherapy for the treatment of axial and paraspinal tumours. PATIENTS AND METHODS Fourteen consecutive patients with axial and paraspinal tumours at the Bergonié Institute between June 2007 and June 2009 were analysed. Various localisations were observed: four paravertebral tumours, five primitive vertebral tumours and six iliosacral or sacral tumours. RESULTS The dose prescribed to the median of the planning target volume (PTV) varied from 45 to 68Gy depending on histology. The maximum dose delivered to the PTV (Dnear max or D2%) was 60.6Gy (range 46.3-69.1). In the five cases where the tumour was located close to the spinal cord, the median value of Dnear max was 40.1Gy (range 37.8-45.4). In the seven where the tumour was situated close to the cauda equina, the median value of Dnear max was 46.5Gy (range 39.2-60). For two cases in whom the sciatic nerve was the nervous structure at risk, the Dnear max was 64.4 and 67Gy. Six patients were in complete remission, six patients suffered a relapse at a median follow-up of 14.5 months (4-24), two died following local tumour progression and metastasis, tumoral stabilisation had been obtained in two patients. Treatment was well tolerated and was never interrupted in all patients. CONCLUSIONS Results from this preliminary series are encouraging, particularly concerning the good tolerance of this new intensity-modulated radiotherapy presently more available than proton therapy.

Cas cliniqueHistiocytose langerhansienne osseuse multifocale : place de la radiothérapieMultifocal Langerhans cell histiocytosis of bone: Indications for radiotherapy

Langerhans cell histiocytosis is a non-malignant proliferative disease of unknown etiology that can affect one or more organs. This is a rare disease, 1 to 2/100,000, affecting mainly children with a male predominance. The osseous lesions are the most frequent (60 to 90%). There is however no consensus treatment for the management of these sites. We report the cases of two patients successfully treated with radiotherapy after primary chemotherapy, at doses of 15 Gy in ten sessions of 1.5 Gy for one patient and 18 Gy in ten fractions of 1.8 Gy for the other. Single or multifocal bone Langerhans cell histiocytosis without visceral involvement is a benign, self-limiting affection in most cases. Some bone lesions could be treated by radiotherapy alone. But the high variability of doses currently given in the literature does not allow determining the lowest effective dose limiting the risk of secondary neoplasia or impaired growth in children, in whom lower doses of 6 to 8 Gy are recommended. The decision of radiotherapy must be weighed against the risk of the disease. Caution should be the rule in this non-malignant tumour pathology.

Histiocytose langerhansienne osseuse multifocale: place de la radiothérapie

Langerhans cell histiocytosis is a non-malignant proliferative disease of unknown etiology that can affect one or more organs. This is a rare disease, 1 to 2/100,000, affecting mainly children with a male predominance. The osseous lesions are the most frequent (60 to 90%). There is however no consensus treatment for the management of these sites. We report the cases of two patients successfully treated with radiotherapy after primary chemotherapy, at doses of 15 Gy in ten sessions of 1.5 Gy for one patient and 18 Gy in ten fractions of 1.8 Gy for the other. Single or multifocal bone Langerhans cell histiocytosis without visceral involvement is a benign, self-limiting affection in most cases. Some bone lesions could be treated by radiotherapy alone. But the high variability of doses currently given in the literature does not allow determining the lowest effective dose limiting the risk of secondary neoplasia or impaired growth in children, in whom lower doses of 6 to 8 Gy are recommended. The decision of radiotherapy must be weighed against the risk of the disease. Caution should be the rule in this non-malignant tumour pathology.

Tomothérapie hélicoïdale : aspects techniques et applications cliniquesHelical tomotherapy: description and clinical applications

Helical tomotherapy is an innovative device combining with the same linac on board-imaging and IMRT facilities. The first national French evaluations, supported by National Institut of Cancer (INCa) are presented. Dosimetric characteristics as quality of homogeneity, cut-off outside target volumes allow IMRT treatments for large and complex volumes and a good organ at risk sparing. First comparative dosimetric studies are discussed.

EP-1398: Acute gastro-intestinal toxicities after pre-operative tomotherapy for retroperitoneal liposarcoma

Material and Methods: From April 2009 to September 2013, 48 patients were included in a prospective multicenter study. Feasibility of tomotherapy, acute toxicities and local control at 3 years were the principal and secondary objectives. Inclusion criteria were operable, biopsy-proven, retroperitoneal liposarcoma. Patients with non-operable tumors validated after multi-disciplinary team evaluation, other histology or metastatic disease were excluded.Clinical Target Volume (CTV) and mains organs at risk (contralateral kidney, duodenum, bowel bag) were systematically delineated with the surgeon. Dose constraints to the bowel bag were defined as V45 Gy<33% and V30 Gy<50%. Surgery was planned 4 to 8 weeks after RT. Clinical visits were performed weekly during RT, before surgery, and 2 and 6 months after surgery. Toxicity was recorded according to CTCAE V4.0 scale.

PO-0753: Use of [18F]-fluoromisonidazole PET for radiotherapy planning in head and neck squamous cell carcinomas

Conclusions: This analysis showed a MDC with a statistically significant advantage in favor of sequence A for both CTV and nodal subvolumes. Nevertheless, MDC in sequence B for CTV and subvolume 1 were close to 0.80 and therefore clinically reliable, with a time sparing of 93%. Final analysis will confirm the clinical reliability and feasibility of the system and the total time sparing for both the Delineator and the Reviewer.