A. Mervoyer

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.

Évaluation de la dose reçue par les organes à risque

The arrival of new technologies and the increase of the possible planned treatments require tools to evaluate and compare the delivered dose to specific organs at risk. Among several options providing the same tumour control, the choice will be made in favour of those that best spare the organs at risk. The evaluation tools have to report acute and late complications, and to be simple to use. The evaluation of the delivered dose to specific organs at risk is currently based on dose-volume histograms, conformal index and the integral dose. However, many questions remain as to reducing the normal tissue toxicity: is it better to deliver a relatively lower dose over a large volume or a relatively higher dose over a smaller volume? The long-term clinical follow-up of patients remains necessary.

Post radiation hysterectomy in locally advanced cervical cancer: Outcomes and dosimetric impact.

PURPOSES Firstly, to evaluate the impact of completion hysterectomy after chemoradiation and image-guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer. Secondly, to assess a potential differential dose-effect relationship for the rectum and bladder according to the realization of hysterectomy. MATERIAL AND METHODS Two cohorts of patients were identified, differing by the realization of completion hysterectomy. Inclusions were limited to FIGO stage I-II, with no para-aortic involvement. All patients received a combination of pelvic chemoradiation followed by IGABT. Their outcomes and morbidity were reviewed. Log-rank tests were used to compare survivals. Probit analyses were performed to study dose-volume effect relationships. RESULTS The two cohorts comprised 54 patients in the completion surgery group and 157 patients in the definitive radiotherapy group. They were well balanced, except for the mean follow-up, significantly longer in the post hysterectomy cohort and the use of PET-CT in the work-up, more frequent in the definitive radiotherapy cohort. Although less local relapses were reported in the hysterectomy group, the 5-year disease-free and overall survival did not differ between groups. The cumulative incidence of severe late morbidity was significantly increased in the hysterectomy cohort: 22.5% versus 6.5% at 5years (p=0.016). Dose-volume effects were observed for the bladder, with the D2cm3 corresponding with a 10% probability of late severe morbidity urinary events (ED10) of 67.8Gy and 91.9Gy in the hysterectomy and definitive radiotherapy cohorts, respectively. A D90 CTVHR of 85Gy (planning aim) corresponded with a 93.3% rate of local control in the definitive radiotherapy cohort whereas it corresponded with a 77.3% chance to have a good histologic response (complete response or microscopic residual disease) in the hysterectomy group. CONCLUSION No benefit from completion hysterectomy in terms of overall or disease-free survival rates was observed, which was moreover responsible for an increase of the severe late morbidity. The realization of post-radiation hysterectomy resulted in a shift of the ED10 of 24.1Gy.

Role of Adjuvant Radiation Therapy After Surgery for Abdominal Desmoplastic Small Round Cell Tumors

PURPOSE To identify the prognostic role of adjuvant abdominal radiation therapy (RT) on oncologic outcomes as a part of multimodal treatment in the management of desmoplastic small round cell tumor (DSRCT) and to determine its impact according to the quality of surgical resection. METHODS AND MATERIALS All patients treated for primary abdominal DSRCT in 8 French centers from 1991 to 2014 were included. Patients were retrospectively staged into 3 groups: group A treated with adjuvant RT after cytoreductive surgery, group B without RT after cytoreductive surgery, and group C by exclusive chemotherapy. Peritoneal progression-free survival (PPFS), progression-free survival (PFS), and overall survival (OS) were evaluated. We also performed a direct comparison between groups A and B to evaluate RT after cytoreductive surgery. Radiation therapy was also evaluated according to completeness of surgery: complete cytoreductive surgery (CCS) or incomplete cytoreductive surgery (ICS). RESULTS Thirty-seven (35.9%), thirty-six (34.9%), and thirty (28.0%) patients were included in groups A, B, and C, respectively. Three-year OS was 61.2% (range, 41.0%-76.0%), 37.6% (22.0%-53.1%), and 17.3% (6.3%-32.8%) for groups A, B, and C, respectively. Overall survival, PPFS, and PFS differed significantly among the 3 groups (P<.001, P<.001, and P<.001, respectively). Overall survival and PPFS were higher in group A (RT group) compared with group B (no RT group) (P=.045 and P=.006, respectively). Three-year PPFS was 23.8% (10.3%-40.4%) for group A and 12.51% (4.0%-26.2%) for group B. After CCS, RT improved PPFS (P=.024), but differences in OS and PFS were not significant (P=.40 and P=.30, respectively). After ICS, RT improved OS (P=.044). A trend of PPFS and PFS increase was observed, but the difference was not statistically significant (P=.073 and P=.076). CONCLUSIONS Adjuvant RT as part of multimodal treatment seems to confer oncologic benefits for patients treated for abdominal DSRCT after cytoreductive surgery and perioperative chemotherapy.

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.

Pre- and postoperative radiotherapy for extremity soft tissue sarcoma: Evaluation of inter-observer target volume contouring variability among French sarcoma group radiation oncologists

PURPOSE The purpose of this study was to evaluate, during a national workshop, the inter-observer variability in target volume delineation for primary extremity soft tissue sarcoma radiation therapy. METHODS AND MATERIALS Six expert sarcoma radiation oncologists (members of French Sarcoma Group) received two extremity soft tissue sarcoma radiation therapy cases 1: one preoperative and one postoperative. They were distributed with instructions for contouring gross tumour volume or reconstructed gross tumour volume, clinical target volume and to propose a planning target volume. The preoperative radiation therapy case was a patient with a grade 1 extraskeletal myxoid chondrosarcoma of the thigh. The postoperative case was a patient with a grade 3 pleomorphic undifferentiated sarcoma of the thigh. Contour agreement analysis was performed using kappa statistics. RESULTS For the preoperative case, contouring agreement regarding GTV, gross tumour volume GTV, clinical target volume and planning target volume were substantial (kappa between 0.68 and 0.77). In the postoperative case, the agreement was only fair for reconstructed gross tumour volume (kappa: 0.38) but moderate for clinical target volume and planning target volume (kappa: 0.42). During the workshop discussion, consensus was reached on most of the contour divergences especially clinical target volume longitudinal extension. The determination of a limited cutaneous cover was also discussed. CONCLUSION Accurate delineation of target volume appears to be a crucial element to ensure multicenter clinical trial quality assessment, reproducibility and homogeneity in delivering RT. radiation therapy RT. Quality assessment process should be proposed in this setting. We have shown in our study that preoperative radiation therapy of extremity soft tissue sarcoma has less inter-observer contouring variability.

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.