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853 poster PEDIATRIC INTRACRANIAL EPENDYMOMA: OUTCOME AND PATTERNS OF FAILURE FOLLOWING POST-OPERATIVE RADIOTHERAPY
H EAD N ECK CANCER
Bilateral RT in these patients, with its increased risk of xerostomia, can be avoided. The risk for contralateral neck recurrence is low even in those patients with N2b disease. 853 poster PEDIATRIC INTRACRANIAL EPENDYMOMA: OUTCOME AND PATTERNS OF FAILURE FOLLOWING POST-OPERATIVE RADIOTHERAPY D. Mansur1 , J. Leonard2 , M. Smyth2 , T. Park2 , D. Limbrick2 , A. King3 , J. Michalski1 , A. Hollander3 , J. Rubin3 1 WASHINGTON U NIVERSITY M EDICAL C ENTER, Radiation Oncology, St. Louis, USA 2 WASHINGTON U NIVERSITY M EDICAL C ENTER, Neurological Surgery, St. Louis, USA 3 WASHINGTON U NIVERSITY M EDICAL C ENTER, Pediatrics, St. Louis, USA Purpose: A retrospective analysis of intracranial ependymoma was performed to determine the efficacy of surgery and post-operative radiation therapy and patterns of failure. Materials: Fifty consecutive patients age less than 20 years with grade II or III intracranial ependymoma and no evidence of disseminated disease have been treated between 1965 and 2008. The majority were male (52%) and had infratentorial tumors (60%). Pathology slides were re-reviewed for the 20 patients for whom material was available. There were 25 World Health Organization (WHO) grade II tumors, and 25 grade III tumors. CSF cytology was documented as negative in only 40% of patients, but no patient had known disseminated disease. All patients received radiation therapy postoperatively to a median dose of 51.3 Gy (range 18-70). Eighteen patients in the earlier era were treated with extended fields (11 craniospinal, and 7 whole brain), while the majority (64%) received local field RT. Results: The median age of patients was 7.2 years (range 1-19). With a median follow up of 4.8 years, the 5 year progression-free survival (PFS) and overall survival (OS) for all patients was 56% and 68%, respectively. Patients treated in the modern imaging era had improved OS (81% vs 50%, p=0.05). Patients with gross total resection had improved OS compared to those with biopsy only or subtotal resection (82.4% vs 58.5%) but this difference did not reach statistical significance. Older children (> 7 years old) had improved PFS (67% vs 44%, p=0.01) and OS (78% vs 58%, p=0.03). Higher radiation dose (>54Gy) was associated with improved PFS (78% vs 39%, p=0.02) and OS (88% vs 52%, p=0.03). Multivariate analysis revealed only younger age to adversely affect PFS. No difference in outcome was seen based on WHO grade, tumor location, gender, or radiation volume. Of the 24 patients who recurred or progressed, 86% did so only within the irradiated volume. No patient had an isolated failure outside the irradiated volume. Conclusions: While the outcome of children with intracranial ependymoma has improved in the modern era, disease progression is common, especially in younger children and after subtotal resection. The dose-response seen and the lack of benefit to extended fields supports the modern radiotherapeutic approach of high-dose RT to limited conformal volumes. 854 poster PHANTOM-BASED VALIDATION OF AN ADAPTIVE RADIOTHERAPY SOFTWARE E. Lennerts1 , J. F. Daisne1 1 C LINIQUE S T. E LISABETH, Radiotherapy Department, Namur, Belgium Purpose: Fractionated stereotactic head and neck radiotherapy is often challenged by patients weight fluctuations, which may cause anatomical modifications with respect to the original planning CT. It may shift the isocenter and reduce plan conformity with PTV underdosage and radiation-induced toxicity as extreme potential consequences. Adaptive radiotherapy (ART) helps to guide treatment plan adaptation in function of organ shape modifications. This requires to re-scan the patient and re-contour both organs at risk (OAR) and target volumes, which is time-consuming and practically impossible to perform online.Brainlab iPlan RT 4.5 ART software was designed to speed up the adaptive workflow process by automatic deformation of delineated volumes from the original planning CT to follow-up CT or CBCT scans. This allows fast and straightforward online evaluation of the validity of the original treatment plan using CBCT data used for patient positioning. We aimed to test and validate the software on a basic phantom model, controlling isovolumetric and volumetric deformations. Materials: A homemade, deformable low neck phantom was homemade with plaster, plasticine and plastic tubes, mimicking 6 vertebras, one mandible, oral cavity and trachea. The plasticine was moulded on a neck support to mimick the neck and oral cavity soft tissues. The phantom was first CTscanned in a native position (CT4) with a native "soft tissue" volume. It was subsequently mechanically deformed and rescanned (three scans: CT1 to CT3), and then shrunken by iteratively removing around 50 cc plasticine each time, followed by rescanning it every time (four scans: CT5 to CT8) The acquired CT-scans were transferred to the Brainlab workstation. "Bony" structures and body contours were manually segmented on every CT-scan. These
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manually contoured gold standard (GS) volumes were compared to the contours resulting from the elastic fusion of the contours of CT4 to CT1 - CT3 and CT5 - CT8. Volume deformation relative accuracy was evaluated by comparing the absolute volume changes between the morphed ART volumes and the GS ones. Dice similarity coefficient (DSC) index was used for objective comparison purpose. Results: All volumes taken together, individual DSC values ranged from 0.90 to 0.99. For the body, the mandible and the six vertebras, the mean DSC indexes were 0.98, 0.94, 0.93, 0.96, 0.95, 0.95, 0.94 and 0.96 respectively. Conclusions: In a simplified non rigid head and neck phantom model, the ART software proved to be accurate. Validation should now be performed on patients’ data sets. 855 poster POSTOPERATIVE CONCURRENT CHEMORADIATION FOR HIGH RISK HEAD & NECK SQUAMOUS CELL CANCER T. Antonadou1 , T. Paschalis2 , A. Silyvridou2 , D. Roumeliotis3 , M. Spyrakos2 , V. Dimakopoulou4 , D. Pantazis3 , N. Throuvalas1 , I. Bankousli4 1 ATHENS M EDICAL C ENTRE, Radiation Oncology, Athens, Greece 2 ATHENS M EDICAL C ENTRE, Medical Physics, Athens, Greece 3 T HRIASION H OSPITAL, Head and Neck Surgery, Greece 4 ATHENS M EDICAL C ENTRE, Oncology, Athens, Greece Purpose: Patients with locally advanced operable head & neck cancer are at high risk for treatment failure. The integration of platinum based concurrent chemoradiotherapy (CRT) has improved loco - regional control leading to improved disease free survival and overall survival. The aim of this study was to evaluate the efficacy and toxicity of concurrent CRT administered after transoral laser surgery. Materials: Between October 2000 and February 2010 112 consecutive patients 105 men and 7 women, with a median age of 65 years (range 33-77) with locally advanced resectable squamous cell head & neck cancer (SCCHN) were referred to our department after transoral laser surgery of the primary tumour and functional neck dissection. All patients underwent platinum based concurrent CRT. Most common chemotherapy (CT) schedule was a weekly 30mg/m2 cisplatinum. Primary sites included larynx (67 pts), oropharynx (40 pts) and hypopharynx (5 pts). AJCC stage was III in 65 pts and IVA in 47 pts. All patients received radiotherapy with 6MV photon beam and 6-12 MeV electron beam combinations. Total dose ranged from 60Gy to 66Gy (2 Gy /5 fractions per week) depending upon the extent of the disease, the surgical excision and the pathology report. 3D treatment planning was performed for all patients and dose volume histograms for PTV, spinal cord and parotid glands were calculated. After beam optimization was performed, PTVs received doses from 95% up to 107%, according to ICRU specifications. Doses to the spinal cord ranged from 42Gy to 48Gy (in less than 2% of the cord) for all patients. Results: All patients completed the treatment protocol and were monitored weekly during CRT. Toxicities were graded following the RTOG scoring criteria. Parotid gland sparing was achieved depending on the tumour primary location, while in cases were the PTV extended superiorly, three quarters of the parotid gland volumes received doses up to 50Gy. Median follow up of the patients was 44 months (range 9-110months). Neither severe acute toxicity nor grade IV haematological toxicity was observed. Acute grade III mucositis was recorded in 62pts (55%), dysphagia in 68pts (61%), xerostomia and dysgeusia in 24pts (21%) respectively. Late radiation side effects were evaluated at 2 years. Only 11pts (10%) presented xerostomia and 5 pts (4%) dysphagia. 4 year disease free survival estimate was 55%. Functional larynx preservation was possible in 57 pts (85%). Conclusions: Concurrent CRT after transoral laser surgery for locally advanced SCCHN is an effective, well tolerated treatment. The loco regional control and overall survival were significantly improved over those reported for radiation treatment alone. It also offers functional organ preservation to the vast majority of the patients with laryngeal carcinoma. 856 poster PREDICTION OF DISPLACEMENT DURING RADIATION THERAPY (INTRAFRACTION MOTION) IN TREATMENT PLANNING FOR PATIENTS WITH HEAD AND NECK NEOPLASM M. Yamamoto1 , H. Hirakawa2 , K. Tanaka3 1 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, Radiation Oncology, Kure, Hiroshima, Japan 2 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, Otolaryngology, Kure, Hiroshima, Japan 3 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, oral surgery, Kure, Hiroshima, Japan Purpose: The development of image guided radiation therapy (IGRT) provides accurate daily patient set-up. However, there is no useful method for prediction of displacement during radiation therapy (intrafraction motion). We prospectively investigated and evaluated the displacement in treatment planning for patients with head and neck neoplasm.
Bilateral RT in these patients, with its increased risk of xerostomia, can be avoided. The risk for contralateral neck recurrence is low even in those patients with N2b disease. 853 poster PEDIATRIC INTRACRANIAL EPENDYMOMA: OUTCOME AND PATTERNS OF FAILURE FOLLOWING POST-OPERATIVE RADIOTHERAPY D. Mansur1 , J. Leonard2 , M. Smyth2 , T. Park2 , D. Limbrick2 , A. King3 , J. Michalski1 , A. Hollander3 , J. Rubin3 1 WASHINGTON U NIVERSITY M EDICAL C ENTER, Radiation Oncology, St. Louis, USA 2 WASHINGTON U NIVERSITY M EDICAL C ENTER, Neurological Surgery, St. Louis, USA 3 WASHINGTON U NIVERSITY M EDICAL C ENTER, Pediatrics, St. Louis, USA Purpose: A retrospective analysis of intracranial ependymoma was performed to determine the efficacy of surgery and post-operative radiation therapy and patterns of failure. Materials: Fifty consecutive patients age less than 20 years with grade II or III intracranial ependymoma and no evidence of disseminated disease have been treated between 1965 and 2008. The majority were male (52%) and had infratentorial tumors (60%). Pathology slides were re-reviewed for the 20 patients for whom material was available. There were 25 World Health Organization (WHO) grade II tumors, and 25 grade III tumors. CSF cytology was documented as negative in only 40% of patients, but no patient had known disseminated disease. All patients received radiation therapy postoperatively to a median dose of 51.3 Gy (range 18-70). Eighteen patients in the earlier era were treated with extended fields (11 craniospinal, and 7 whole brain), while the majority (64%) received local field RT. Results: The median age of patients was 7.2 years (range 1-19). With a median follow up of 4.8 years, the 5 year progression-free survival (PFS) and overall survival (OS) for all patients was 56% and 68%, respectively. Patients treated in the modern imaging era had improved OS (81% vs 50%, p=0.05). Patients with gross total resection had improved OS compared to those with biopsy only or subtotal resection (82.4% vs 58.5%) but this difference did not reach statistical significance. Older children (> 7 years old) had improved PFS (67% vs 44%, p=0.01) and OS (78% vs 58%, p=0.03). Higher radiation dose (>54Gy) was associated with improved PFS (78% vs 39%, p=0.02) and OS (88% vs 52%, p=0.03). Multivariate analysis revealed only younger age to adversely affect PFS. No difference in outcome was seen based on WHO grade, tumor location, gender, or radiation volume. Of the 24 patients who recurred or progressed, 86% did so only within the irradiated volume. No patient had an isolated failure outside the irradiated volume. Conclusions: While the outcome of children with intracranial ependymoma has improved in the modern era, disease progression is common, especially in younger children and after subtotal resection. The dose-response seen and the lack of benefit to extended fields supports the modern radiotherapeutic approach of high-dose RT to limited conformal volumes. 854 poster PHANTOM-BASED VALIDATION OF AN ADAPTIVE RADIOTHERAPY SOFTWARE E. Lennerts1 , J. F. Daisne1 1 C LINIQUE S T. E LISABETH, Radiotherapy Department, Namur, Belgium Purpose: Fractionated stereotactic head and neck radiotherapy is often challenged by patients weight fluctuations, which may cause anatomical modifications with respect to the original planning CT. It may shift the isocenter and reduce plan conformity with PTV underdosage and radiation-induced toxicity as extreme potential consequences. Adaptive radiotherapy (ART) helps to guide treatment plan adaptation in function of organ shape modifications. This requires to re-scan the patient and re-contour both organs at risk (OAR) and target volumes, which is time-consuming and practically impossible to perform online.Brainlab iPlan RT 4.5 ART software was designed to speed up the adaptive workflow process by automatic deformation of delineated volumes from the original planning CT to follow-up CT or CBCT scans. This allows fast and straightforward online evaluation of the validity of the original treatment plan using CBCT data used for patient positioning. We aimed to test and validate the software on a basic phantom model, controlling isovolumetric and volumetric deformations. Materials: A homemade, deformable low neck phantom was homemade with plaster, plasticine and plastic tubes, mimicking 6 vertebras, one mandible, oral cavity and trachea. The plasticine was moulded on a neck support to mimick the neck and oral cavity soft tissues. The phantom was first CTscanned in a native position (CT4) with a native "soft tissue" volume. It was subsequently mechanically deformed and rescanned (three scans: CT1 to CT3), and then shrunken by iteratively removing around 50 cc plasticine each time, followed by rescanning it every time (four scans: CT5 to CT8) The acquired CT-scans were transferred to the Brainlab workstation. "Bony" structures and body contours were manually segmented on every CT-scan. These
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manually contoured gold standard (GS) volumes were compared to the contours resulting from the elastic fusion of the contours of CT4 to CT1 - CT3 and CT5 - CT8. Volume deformation relative accuracy was evaluated by comparing the absolute volume changes between the morphed ART volumes and the GS ones. Dice similarity coefficient (DSC) index was used for objective comparison purpose. Results: All volumes taken together, individual DSC values ranged from 0.90 to 0.99. For the body, the mandible and the six vertebras, the mean DSC indexes were 0.98, 0.94, 0.93, 0.96, 0.95, 0.95, 0.94 and 0.96 respectively. Conclusions: In a simplified non rigid head and neck phantom model, the ART software proved to be accurate. Validation should now be performed on patients’ data sets. 855 poster POSTOPERATIVE CONCURRENT CHEMORADIATION FOR HIGH RISK HEAD & NECK SQUAMOUS CELL CANCER T. Antonadou1 , T. Paschalis2 , A. Silyvridou2 , D. Roumeliotis3 , M. Spyrakos2 , V. Dimakopoulou4 , D. Pantazis3 , N. Throuvalas1 , I. Bankousli4 1 ATHENS M EDICAL C ENTRE, Radiation Oncology, Athens, Greece 2 ATHENS M EDICAL C ENTRE, Medical Physics, Athens, Greece 3 T HRIASION H OSPITAL, Head and Neck Surgery, Greece 4 ATHENS M EDICAL C ENTRE, Oncology, Athens, Greece Purpose: Patients with locally advanced operable head & neck cancer are at high risk for treatment failure. The integration of platinum based concurrent chemoradiotherapy (CRT) has improved loco - regional control leading to improved disease free survival and overall survival. The aim of this study was to evaluate the efficacy and toxicity of concurrent CRT administered after transoral laser surgery. Materials: Between October 2000 and February 2010 112 consecutive patients 105 men and 7 women, with a median age of 65 years (range 33-77) with locally advanced resectable squamous cell head & neck cancer (SCCHN) were referred to our department after transoral laser surgery of the primary tumour and functional neck dissection. All patients underwent platinum based concurrent CRT. Most common chemotherapy (CT) schedule was a weekly 30mg/m2 cisplatinum. Primary sites included larynx (67 pts), oropharynx (40 pts) and hypopharynx (5 pts). AJCC stage was III in 65 pts and IVA in 47 pts. All patients received radiotherapy with 6MV photon beam and 6-12 MeV electron beam combinations. Total dose ranged from 60Gy to 66Gy (2 Gy /5 fractions per week) depending upon the extent of the disease, the surgical excision and the pathology report. 3D treatment planning was performed for all patients and dose volume histograms for PTV, spinal cord and parotid glands were calculated. After beam optimization was performed, PTVs received doses from 95% up to 107%, according to ICRU specifications. Doses to the spinal cord ranged from 42Gy to 48Gy (in less than 2% of the cord) for all patients. Results: All patients completed the treatment protocol and were monitored weekly during CRT. Toxicities were graded following the RTOG scoring criteria. Parotid gland sparing was achieved depending on the tumour primary location, while in cases were the PTV extended superiorly, three quarters of the parotid gland volumes received doses up to 50Gy. Median follow up of the patients was 44 months (range 9-110months). Neither severe acute toxicity nor grade IV haematological toxicity was observed. Acute grade III mucositis was recorded in 62pts (55%), dysphagia in 68pts (61%), xerostomia and dysgeusia in 24pts (21%) respectively. Late radiation side effects were evaluated at 2 years. Only 11pts (10%) presented xerostomia and 5 pts (4%) dysphagia. 4 year disease free survival estimate was 55%. Functional larynx preservation was possible in 57 pts (85%). Conclusions: Concurrent CRT after transoral laser surgery for locally advanced SCCHN is an effective, well tolerated treatment. The loco regional control and overall survival were significantly improved over those reported for radiation treatment alone. It also offers functional organ preservation to the vast majority of the patients with laryngeal carcinoma. 856 poster PREDICTION OF DISPLACEMENT DURING RADIATION THERAPY (INTRAFRACTION MOTION) IN TREATMENT PLANNING FOR PATIENTS WITH HEAD AND NECK NEOPLASM M. Yamamoto1 , H. Hirakawa2 , K. Tanaka3 1 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, Radiation Oncology, Kure, Hiroshima, Japan 2 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, Otolaryngology, Kure, Hiroshima, Japan 3 K URE N ATIONAL H OSPITAL , C HUGOKU D ISTRICT C ANCER C E, oral surgery, Kure, Hiroshima, Japan Purpose: The development of image guided radiation therapy (IGRT) provides accurate daily patient set-up. However, there is no useful method for prediction of displacement during radiation therapy (intrafraction motion). We prospectively investigated and evaluated the displacement in treatment planning for patients with head and neck neoplasm.