- Email: [email protected]
Secondary Cancer Risk Analysis: Evaluation of VMAT Versus Dynamic IMRT Planning in Treatment of Head and Neck Cancer by Simultaneously Integrated Boost Technique
S568
International Journal of Radiation Oncology Biology Physics
Materials/Methods: To address these late toxicities we reviewed our IRB approved registry with improved follow-up compared to our previously reported patient series. In contrast to previous work, we identified all patients with stage III-IV tumors of the larynx, hypopharynx and HPVnegative oropharynx treated between 1995-2012 with definitive CRT who acutely required a feeding tube during therapy. Patients with less than one year of follow-up and those who failed therapy within two years were excluded. CTCAE v4.0 criteria were used to evaluate for severe (Grade 3) late pharyngeal toxicity defined as the need for stricture dilation or chronic enteral feeding dependence. Logistic regression was used to control for treatment parameters. Results: Seventy-eight survivors who acutely required a feeding tube and met the strict criteria above were identified. Median follow-up was 61.7 months (range 11.0-197.80 months). In 3 patients feeding was necessary prior to radiation (2 PEG, 1 NG). The primary tumor was located in the larynx in 40 (51.3%), hypopharynx in 25 (32.1%) and (HPV-negative) oropharynx in 13 (16.7%) and 75.6% of tumors were locally-advanced (T3-T4). 3D-Conformal Radiation therapy (3D-CRT) was used in 84.6% and Intensity-Modulated Radiation therapy (IMRT) in 15.4%. A temporary small-bore NG tube was used in 29 patients (37.2%) and a PEG in 49 (62.8%). 31.0% of the NG patients experienced late pharyngeal toxicity compared to 57.1% of the PEG patients. On univariate analysis the use of PEG feeding was the only factor significantly associated with an increased risk of this severe toxicity (OR 2.96, 95% CI 1.12-7.81; p Z 0.028). Age, T-stage, N-stage, adjuvant neck dissection, multiagent chemotherapy, hyperfractionated radiation therapy or the use of IMRT were not associated, although there was a trend towards increased toxicity in patients with hypopharynx primaries (p Z 0.058). On multivariate analysis, when controlling for location of the primary tumor, the use of a PEG tube remained independently associated with late pharyngeal toxicity (OR 2.83, 95% CI 1.04-7.69, p Z 0.042). Conclusions: Our updated series with long-term follow-up shows that PEG tubes are associated with significantly higher rates of severe late pharyngeal toxicity as opposed to NG tubes. Routine PEG use should be avoided when possible to encourage pharyngeal exercise and prevent late strictures. Author Disclosure: M.C. Ward: None. P. Bhateja: None. T.B. Bledsoe: None. D.J. Adelstein: E. Research Grant; Sanofi-Aventis, GlaxoSmithKline. T. Nwizu: None. J.F. Greskovich: G. Consultant; Philips. H. Speakers Bureau; Siemens. I. Travel Expenses; Philips, Siemens, Elekta. C.A. Reddy: None. B.B. Burkey: None. P. Xia: None. S.A. Koyfman: None.
was II (16.7%), III (16.7%), IVA (58.3%) and IVB (8.3%). Median CD4 count prior to RT was 261 cells/uL (range 71-858 cells/uL). Pathologic confirmation of human papilloma virus (HPV) was available for 3 patients, 2 were HPV positive. Radiation therapy technique was 3D-conformal (62.5%) or intensity modulated radiation therapy (37.5%); 11 patients (45.8%) had concurrent chemoradiation therapy. Thirteen patients (54%) underwent definitive RT and 11 (46%) were treated adjuvantly. At most recent follow-up, 16 patients (66.7%) were alive, 20 patients (83.3%) were free of local recurrence and 19 (79%) were free of distant metastases. Kaplan-Meier estimated 3- year OS was 61% (median OS 83 mos, 95% CI 10-155 mos), LRFS was 82%, DMFS was 77% and DFS was 73%. Conclusions: In our cohort, HIV+ patients had excellent disease-related outcomes and overall survival following primary or adjuvant RT or CRT for head and neck SCC. These results suggest HIV+ patients carry a positive prognostic factor, such as high rates of HPV positivity. This group of patients should be managed aggressively with intent to cure. Author Disclosure: D. Grew: None. B. Smith: None. S. Nguy: None. N. Sanfilippo: None.
2907 Disease Outcomes in Human Immunodeficiency VirusePositive Patients Treated With Primary or Adjuvant Radiation Therapy for Head and Neck Cancer D. Grew, B. Smith, S. Nguy, and N. Sanfilippo; NYU Medical Center, New York, NY Purpose/Objective(s): Human immunodeficiency virus (HIV) seropositivity may be associated with higher risk of local recurrence and poor survival in multiple malignancies. However, long-term disease control in HIV+ patients with head and neck cancer is not well described. The purpose of this study is to review the disease-related outcomes of HIV+ patients who underwent radiation therapy (RT) at our institution. Materials/Methods: We retrospectively reviewed 24 consecutive HIV+ patients who underwent definitive or adjuvant RT for squamous cell carcinoma (SCC) of the head and neck at a single institution between 2004 and 2013. Data on patient characteristics, RT dose and technique and treatment outcomes were collected from patient charts. Stage was recorded according to AJCC 7th edition. Overall survival (OS), local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS) and disease-free survival (DFS) was investigated. Kaplan-Meier estimated survival was calculated. Results: Median follow up was 21 months. Eighty-three percent were male; median age was 53 years old. Twenty-three patients (96%) had SCC and one patient had sarcomatoid SCC. Primary sites of disease included oropharynx (n Z 12), larynx (n Z 6), oral cavity (n Z 2), unknown primary (n Z 2), nasal cavity (n Z 1),and paranasal sinuses (n Z 1). Stage
2908 Secondary Cancer Risk Analysis: Evaluation of VMAT Versus Dynamic IMRT Planning in Treatment of Head and Neck Cancer by Simultaneously Integrated Boost Technique V. Sakthivel,1 G. Kadirampatti,2 S. Mani,1 J. Berilgen,3 and R. Boopathy1; 1 Advanced Medical Physics, Houston, TX, 2Kidwai Memorial Institute of Oncology, Bangalore, India, 3Millennium Oncology, The Woodlands, TX Purpose/Objective(s): To compare the secondary cancer risk (SCR) between different planning techniques for treatment of Head and Neck cancer patients using the concept of OED. Materials/Methods: Five treatment plans were generated. 7 and 9 field plans for both 6 and 15 MV (7F6, 9F6, 7F15, 9F15) IMRT, 6 MV volumetric modulated arc therapy (VMAT) plan with two complementary arcs. The dose regimen was 58.1 Gy to elective nodes, 63 Gy to involved site and 70 Gy to primary in 35 fractions. The OED for OARs were evaluated by linear-exponential, plateau, and the linear dose-response model. In addition, the low dose-bath volumes were analyzed. Results: The SCR values for all plans are compared against the 7 field 6 MV IMRT plan. For brainstem and cord all three models trended higher relative SCR values for VMAT plan (17-22 %), with 15 MV IMRT being the least with -14%. In parotids no significant difference between IMRT plans were observed however the VMAT plan showed relative SCR of + 5% on the involved side and -4% on the non-involved side. The relative OED for Larynx was -4% in VMAT plan. For skin 9F6 and VMAT had the higher SCR, 5 and 8% respectively. Low dose volumes of 5, 10, 20 and 30 Gy for VMAT compared with 7F6 were 5.9, 11.6, 8.9, 11 % respectively. For brain SCR for VMAT were higher by 13 - 17%. The overall relative effective OED for 9F6, 7F15, 9F15 and VMAT were 0.99, 0.98, 0.99 and 1.15 respectively. Conclusions: Study suggests higher cancer risk for Head and Neck patients treated with VMAT. For structures outside the primary beam like brainstem and brain the SCR values for VMAT are very high compared with the structures inside the primary beam. For non-involved parotid and larynx the VMAT plan had the lesser SCR of (-4%) because of its higher degrees of freedom to modulate the beam. No significant difference was observed between 7 and 9 fields IMRT. For superficial structures the SCR is independent on energy and for deep seated structures higher energy resulted in lesser SCR. Scientific Abstract 2908; Table Exponential)
Brain Brain Stem Spinal Cord Right Parotid Left Parotid Larynx Skin
Relative OED (Linear/Plateau/Linear
7F6
9F6
7F15
9F15
VMAT
1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.06/1.02/1.02 1.05/1.0/1.01 1.02/1.0/1.01 0.99/1.0/1.02 1.01/1.0/1.0 1.04/0.97/1.0 1.1/1.05/1.05
0.95/0.88/0.87 1.0/0.94/0.95 1.03/0.98/0.99 0.99/1.0/1.0 1.01/0.97/1.0 1.04/0.97/1.0 0.97/1.01/1.0
0.97/0.87/0.86 1.02/0.92/0.93 1.03/0.99/0.99 0.98/1.03/1.02 1.0/1.0/1.01 1.04/0.96/1.0 1.02/1.04/1.04
1.13/1.17/1.16 1.21/1.22/1.19 1.06/1.03/1.03 1.13/1.05/1.05 0.99/0.96/0.97 0.79/1.1/0.98 1.07/1.08/1.07
Volume 90 Number 1S Supplement 2014 Author Disclosure: V. Sakthivel: None. G. Kadirampatti: None. S. Mani: None. J. Berilgen: None. R. Boopathy: None.
2909 Head and Neck Cancer Patients With False Negative Surveillance FDG PET/CT Scans Show Unique Clinical Characteristics and Disease Recurrence Patterns A. Hoover, C. Anderson, M. TenNapel, P. Goswami, Y. Menda, and J. Buatti; University of Iowa Hospitals and Clinics, Iowa City, IA Purpose/Objective(s): Despite its clinical utility in improving post therapy surveillance for head and neck cancer (HNC), PET/CT imaging suffers from poor sensitivity due to high false negative (FN) rates. Consistent with a 2011 meta-analysis, our recently updated institutional experience with 3 month post radiation therapy (RT) surveillance PET/CT revealed a sensitivity of just 62.5%. Further optimization of the performance characteristics of surveillance PET/CT will require better understanding of factors contributing to FN scan interpretations. We hypothesize that FN scans are caused by more slowly proliferative, less metabolically active cancers which are unlikely to be PET avid at early time points after therapy. To test this hypothesis, we reviewed our 3 month surveillance PET/CT data, comparing clinical, imaging, and pathologic characteristics between patients with TP (true positive) and FN scans. Materials/Methods: This was an IRB approved review of 191 patients treated with RT for HNC between November 2003 and May 2008. All patients had surveillance PET/CT scans 3 months after completing RT. PET/CT scans were categorized as positive or negative based on review of nuclear medicine reports in the medical record. We defined scans as TP if the patient developed biopsy proven disease recurrence within 1 year of a positively interpreted 3 month surveillance PET/CT, and FN if the patient developed biopsy proven disease recurrence within one year of a negatively interpreted 3 month PET/CT. Results: Thirty-two patients developed biopsy confirmed disease recurrences within one year of their 3 month post RT PET/CT, including 13 patients with FN and 19 patients with TP findings. Median time from 3 month PET/CT to biopsy confirmed disease recurrence was 0.9 and 5.7 months for TP and FN patients, respectively. Median survival from biopsy confirmed recurrence was 8.7 months for TP and 21.3 months for FN patients (p Z 0.02). The median SUV max of diagnostic, pre-therapy PET/ CT scans was 8.9 for the FN cohort and 14.2 for the TP cohort (p Z 0.07). Among the 13 patients with FN scans, 12 had repeat PET/CT scans at the time of biopsy, of which 10 were interpreted as positive. Conclusions: Consistent with our hypothesis, our results show patients with FN 3 month surveillance PET/CT scans represent a distinct patient cohort, characterized by decreased pre-therapy diagnostic SUV max relative to patients with TP scans. These patients develop late disease recurrences that do not become PET avid until time points beyond 3 months and have longer survival after disease recurrence is documented. Future efforts aimed at reliably identifying this patient group based on pre-therapy clinical characteristics may lead to a decrease in FN scans due to improved patient selection and timing of surveillance PET/CT imaging. Author Disclosure: A. Hoover: A. Employee; University of Iowa Hospitals and Clinics. C. Anderson: A. Employee; University of Iowa Hospitals and Clinics. M. TenNapel: A. Employee; University of Iowa Hospitals and Clinics. P. Goswami: A. Employee; University of Iowa Hospitals and Clinics. Y. Menda: A. Employee; University of Iowa Hospitals and Clinics. J. Buatti: A. Employee; University of Iowa Hospitals and Clinics.
2910 Volumetric Regression Ratio of Tumor and Involved Lymph Nodes After Induction Chemotherapy Predicts the Overall Survival in Head and Neck Cancer O. Elicin,1 M. Schmu¨cking,1 J. Bro¨mme,1 R. Giger,2 D. Rauch,3 D. Leiser,1 P. Ambarcioglu,4 L. Plasswilm,5 A. Geretschla¨ger,1 P. Ghadjar,1 and D.M. Aebersold1; 1Department of Radiation Oncology, Inselspital, University of Bern, Bern, Switzerland, 2Department of ORL, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland,
Poster Viewing Abstracts S569 3
Department of Medical Oncology, Inselspital, University of Bern, Bern, Switzerland, 4Department of Biostatistics, Istanbul University Cerrahpasa Faculty of Medicine, Istanbul, Turkey, 5Department of Radiation Oncology, Kantonspital St. Gallen, St. Galen, Switzerland Purpose/Objective(s): Pre-treatment volumetric evaluation of disease burden predicts outcome in Head and Neck Squamous Cell Cancer (HNSCC). We looked for any predictive value of change in primary tumor and nodal volumes after induction chemotherapy (IC) on oncologic outcome. Materials/Methods: Twenty-three patients with Stage IVA/B non-nasopharyngeal HNSCC treated between 2004 and 2010 with at least one cycle of IC (Docetaxel, Cisplatin and 5-Fluorouracil) and definitive chemo-radiation therapy (CRT) with Cisplatin were retrospectively analyzed. Volumes were calculated separately for primary tumor (Vtm), lymph nodes (Vln) and their sum (Vsum) on computed tomography (CT) images before and after IC. The effect of volumetric changes on loco-regional failure (LRF), distant metastasis (DM) and overall survival (OS) were assessed. Optimal cut-off values for changes in volumes were defined using receiver operating characteristic analyses. Their association with clinical failure and survival were assessed with log-rank tests. p values <0.05 were considered as statistically significant. Results: The cohort had a median age of 57 years (range: 41-73) and a median follow-up of 18.25 months (9-53). Median cycles of IC was 3 (1-5) and the time from the start of first cycle of chemotherapy to start of CRT was 98 days (19-263). Decrease in mean Vtm, Vln and Vsum after IC were statistically significant among each other (p <0.03). Empirical area under the curve (AUC) analyses for conditions; death, LRF and DM revealed optimal cut-off values of Vtm (30.54%, AUC: 87%) and Vsum (35.4%, AUC: 64.55%) only for OS (p <0.05). Among those, a reduction in Vsum more than 35.4% between pre- and post-IC was significantly correlated with better OS (100% vs 56% at 18 months, p <0.03). Conclusions: Volumetric shrinkage in tumor and involved lymph nodes after IC assessed with CT seems to predict overall survival. This methodology may be implemented especially in countries and healthcare settings where resources for Magnetic Resonance Imaging or Positron Emission Tomography are limited. As recently demonstrated in a randomized phase 3 trial IC added to CRT is not superior to CRT alone in the general population of locally advanced HNSCC patients. However, to choose IC for selected cases with bulky disease remains to be an option. The assessment of volumetric shrinkage upon IC might be used to decide whether to offer patients less or more aggressive treatment alternatives after IC. However, strategies like this should be first validated in settings of randomized trials before being used in treatment decision algorithms. Author Disclosure: O. Elicin: None. M. Schmu¨cking: None. J. Bro¨mme: None. R. Giger: None. D. Rauch: None. D. Leiser: None. P. Ambarcioglu: None. L. Plasswilm: None. A. Geretschla¨ger: None. P. Ghadjar: None. D.M. Aebersold: None.
2911 Methods for Analysis and Reporting the Patterns of Locoregional Failure in the Era of IMRT for Head and Neck Cancer: Deformable Image RegistrationeBased Quality Assurance Workflow A.S. Mohamed,1 M. Awan,2 E. Kocak,3 B.M. Beadle,4 M.E. Kantor,5 G.B. Gunn,1 A.S. Garden,4 D.I. Rosenthal,1 and C.D. Fuller5; 1University of Texas MD Anderson Cancer Center, Houston, TX, 2George Washington School of Medicine, Washington, DC, MD, 3Istanbul University, Istanbul, DC, 4University of Texas MD Anderson Anderson Cancer Center, Houston, TX, 5University of Texas MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): The accurate and specific reporting of the exact site of loco-regional failure after intensity modulated radiation therapy (IMRT) of head and neck cancer in addition to the dose given to this site is mandatory to identify the possible causes of failure. Our aim is to develop a workflow methodology to accurately define the area of recurrent/ persistent disease relative to the original planning target volumes (TVs) and prescribed radiation doses using a validated deformable image registration (DIR) software.
International Journal of Radiation Oncology Biology Physics
Materials/Methods: To address these late toxicities we reviewed our IRB approved registry with improved follow-up compared to our previously reported patient series. In contrast to previous work, we identified all patients with stage III-IV tumors of the larynx, hypopharynx and HPVnegative oropharynx treated between 1995-2012 with definitive CRT who acutely required a feeding tube during therapy. Patients with less than one year of follow-up and those who failed therapy within two years were excluded. CTCAE v4.0 criteria were used to evaluate for severe (Grade 3) late pharyngeal toxicity defined as the need for stricture dilation or chronic enteral feeding dependence. Logistic regression was used to control for treatment parameters. Results: Seventy-eight survivors who acutely required a feeding tube and met the strict criteria above were identified. Median follow-up was 61.7 months (range 11.0-197.80 months). In 3 patients feeding was necessary prior to radiation (2 PEG, 1 NG). The primary tumor was located in the larynx in 40 (51.3%), hypopharynx in 25 (32.1%) and (HPV-negative) oropharynx in 13 (16.7%) and 75.6% of tumors were locally-advanced (T3-T4). 3D-Conformal Radiation therapy (3D-CRT) was used in 84.6% and Intensity-Modulated Radiation therapy (IMRT) in 15.4%. A temporary small-bore NG tube was used in 29 patients (37.2%) and a PEG in 49 (62.8%). 31.0% of the NG patients experienced late pharyngeal toxicity compared to 57.1% of the PEG patients. On univariate analysis the use of PEG feeding was the only factor significantly associated with an increased risk of this severe toxicity (OR 2.96, 95% CI 1.12-7.81; p Z 0.028). Age, T-stage, N-stage, adjuvant neck dissection, multiagent chemotherapy, hyperfractionated radiation therapy or the use of IMRT were not associated, although there was a trend towards increased toxicity in patients with hypopharynx primaries (p Z 0.058). On multivariate analysis, when controlling for location of the primary tumor, the use of a PEG tube remained independently associated with late pharyngeal toxicity (OR 2.83, 95% CI 1.04-7.69, p Z 0.042). Conclusions: Our updated series with long-term follow-up shows that PEG tubes are associated with significantly higher rates of severe late pharyngeal toxicity as opposed to NG tubes. Routine PEG use should be avoided when possible to encourage pharyngeal exercise and prevent late strictures. Author Disclosure: M.C. Ward: None. P. Bhateja: None. T.B. Bledsoe: None. D.J. Adelstein: E. Research Grant; Sanofi-Aventis, GlaxoSmithKline. T. Nwizu: None. J.F. Greskovich: G. Consultant; Philips. H. Speakers Bureau; Siemens. I. Travel Expenses; Philips, Siemens, Elekta. C.A. Reddy: None. B.B. Burkey: None. P. Xia: None. S.A. Koyfman: None.
was II (16.7%), III (16.7%), IVA (58.3%) and IVB (8.3%). Median CD4 count prior to RT was 261 cells/uL (range 71-858 cells/uL). Pathologic confirmation of human papilloma virus (HPV) was available for 3 patients, 2 were HPV positive. Radiation therapy technique was 3D-conformal (62.5%) or intensity modulated radiation therapy (37.5%); 11 patients (45.8%) had concurrent chemoradiation therapy. Thirteen patients (54%) underwent definitive RT and 11 (46%) were treated adjuvantly. At most recent follow-up, 16 patients (66.7%) were alive, 20 patients (83.3%) were free of local recurrence and 19 (79%) were free of distant metastases. Kaplan-Meier estimated 3- year OS was 61% (median OS 83 mos, 95% CI 10-155 mos), LRFS was 82%, DMFS was 77% and DFS was 73%. Conclusions: In our cohort, HIV+ patients had excellent disease-related outcomes and overall survival following primary or adjuvant RT or CRT for head and neck SCC. These results suggest HIV+ patients carry a positive prognostic factor, such as high rates of HPV positivity. This group of patients should be managed aggressively with intent to cure. Author Disclosure: D. Grew: None. B. Smith: None. S. Nguy: None. N. Sanfilippo: None.
2907 Disease Outcomes in Human Immunodeficiency VirusePositive Patients Treated With Primary or Adjuvant Radiation Therapy for Head and Neck Cancer D. Grew, B. Smith, S. Nguy, and N. Sanfilippo; NYU Medical Center, New York, NY Purpose/Objective(s): Human immunodeficiency virus (HIV) seropositivity may be associated with higher risk of local recurrence and poor survival in multiple malignancies. However, long-term disease control in HIV+ patients with head and neck cancer is not well described. The purpose of this study is to review the disease-related outcomes of HIV+ patients who underwent radiation therapy (RT) at our institution. Materials/Methods: We retrospectively reviewed 24 consecutive HIV+ patients who underwent definitive or adjuvant RT for squamous cell carcinoma (SCC) of the head and neck at a single institution between 2004 and 2013. Data on patient characteristics, RT dose and technique and treatment outcomes were collected from patient charts. Stage was recorded according to AJCC 7th edition. Overall survival (OS), local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS) and disease-free survival (DFS) was investigated. Kaplan-Meier estimated survival was calculated. Results: Median follow up was 21 months. Eighty-three percent were male; median age was 53 years old. Twenty-three patients (96%) had SCC and one patient had sarcomatoid SCC. Primary sites of disease included oropharynx (n Z 12), larynx (n Z 6), oral cavity (n Z 2), unknown primary (n Z 2), nasal cavity (n Z 1),and paranasal sinuses (n Z 1). Stage
2908 Secondary Cancer Risk Analysis: Evaluation of VMAT Versus Dynamic IMRT Planning in Treatment of Head and Neck Cancer by Simultaneously Integrated Boost Technique V. Sakthivel,1 G. Kadirampatti,2 S. Mani,1 J. Berilgen,3 and R. Boopathy1; 1 Advanced Medical Physics, Houston, TX, 2Kidwai Memorial Institute of Oncology, Bangalore, India, 3Millennium Oncology, The Woodlands, TX Purpose/Objective(s): To compare the secondary cancer risk (SCR) between different planning techniques for treatment of Head and Neck cancer patients using the concept of OED. Materials/Methods: Five treatment plans were generated. 7 and 9 field plans for both 6 and 15 MV (7F6, 9F6, 7F15, 9F15) IMRT, 6 MV volumetric modulated arc therapy (VMAT) plan with two complementary arcs. The dose regimen was 58.1 Gy to elective nodes, 63 Gy to involved site and 70 Gy to primary in 35 fractions. The OED for OARs were evaluated by linear-exponential, plateau, and the linear dose-response model. In addition, the low dose-bath volumes were analyzed. Results: The SCR values for all plans are compared against the 7 field 6 MV IMRT plan. For brainstem and cord all three models trended higher relative SCR values for VMAT plan (17-22 %), with 15 MV IMRT being the least with -14%. In parotids no significant difference between IMRT plans were observed however the VMAT plan showed relative SCR of + 5% on the involved side and -4% on the non-involved side. The relative OED for Larynx was -4% in VMAT plan. For skin 9F6 and VMAT had the higher SCR, 5 and 8% respectively. Low dose volumes of 5, 10, 20 and 30 Gy for VMAT compared with 7F6 were 5.9, 11.6, 8.9, 11 % respectively. For brain SCR for VMAT were higher by 13 - 17%. The overall relative effective OED for 9F6, 7F15, 9F15 and VMAT were 0.99, 0.98, 0.99 and 1.15 respectively. Conclusions: Study suggests higher cancer risk for Head and Neck patients treated with VMAT. For structures outside the primary beam like brainstem and brain the SCR values for VMAT are very high compared with the structures inside the primary beam. For non-involved parotid and larynx the VMAT plan had the lesser SCR of (-4%) because of its higher degrees of freedom to modulate the beam. No significant difference was observed between 7 and 9 fields IMRT. For superficial structures the SCR is independent on energy and for deep seated structures higher energy resulted in lesser SCR. Scientific Abstract 2908; Table Exponential)
Brain Brain Stem Spinal Cord Right Parotid Left Parotid Larynx Skin
Relative OED (Linear/Plateau/Linear
7F6
9F6
7F15
9F15
VMAT
1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.06/1.02/1.02 1.05/1.0/1.01 1.02/1.0/1.01 0.99/1.0/1.02 1.01/1.0/1.0 1.04/0.97/1.0 1.1/1.05/1.05
0.95/0.88/0.87 1.0/0.94/0.95 1.03/0.98/0.99 0.99/1.0/1.0 1.01/0.97/1.0 1.04/0.97/1.0 0.97/1.01/1.0
0.97/0.87/0.86 1.02/0.92/0.93 1.03/0.99/0.99 0.98/1.03/1.02 1.0/1.0/1.01 1.04/0.96/1.0 1.02/1.04/1.04
1.13/1.17/1.16 1.21/1.22/1.19 1.06/1.03/1.03 1.13/1.05/1.05 0.99/0.96/0.97 0.79/1.1/0.98 1.07/1.08/1.07
Volume 90 Number 1S Supplement 2014 Author Disclosure: V. Sakthivel: None. G. Kadirampatti: None. S. Mani: None. J. Berilgen: None. R. Boopathy: None.
2909 Head and Neck Cancer Patients With False Negative Surveillance FDG PET/CT Scans Show Unique Clinical Characteristics and Disease Recurrence Patterns A. Hoover, C. Anderson, M. TenNapel, P. Goswami, Y. Menda, and J. Buatti; University of Iowa Hospitals and Clinics, Iowa City, IA Purpose/Objective(s): Despite its clinical utility in improving post therapy surveillance for head and neck cancer (HNC), PET/CT imaging suffers from poor sensitivity due to high false negative (FN) rates. Consistent with a 2011 meta-analysis, our recently updated institutional experience with 3 month post radiation therapy (RT) surveillance PET/CT revealed a sensitivity of just 62.5%. Further optimization of the performance characteristics of surveillance PET/CT will require better understanding of factors contributing to FN scan interpretations. We hypothesize that FN scans are caused by more slowly proliferative, less metabolically active cancers which are unlikely to be PET avid at early time points after therapy. To test this hypothesis, we reviewed our 3 month surveillance PET/CT data, comparing clinical, imaging, and pathologic characteristics between patients with TP (true positive) and FN scans. Materials/Methods: This was an IRB approved review of 191 patients treated with RT for HNC between November 2003 and May 2008. All patients had surveillance PET/CT scans 3 months after completing RT. PET/CT scans were categorized as positive or negative based on review of nuclear medicine reports in the medical record. We defined scans as TP if the patient developed biopsy proven disease recurrence within 1 year of a positively interpreted 3 month surveillance PET/CT, and FN if the patient developed biopsy proven disease recurrence within one year of a negatively interpreted 3 month PET/CT. Results: Thirty-two patients developed biopsy confirmed disease recurrences within one year of their 3 month post RT PET/CT, including 13 patients with FN and 19 patients with TP findings. Median time from 3 month PET/CT to biopsy confirmed disease recurrence was 0.9 and 5.7 months for TP and FN patients, respectively. Median survival from biopsy confirmed recurrence was 8.7 months for TP and 21.3 months for FN patients (p Z 0.02). The median SUV max of diagnostic, pre-therapy PET/ CT scans was 8.9 for the FN cohort and 14.2 for the TP cohort (p Z 0.07). Among the 13 patients with FN scans, 12 had repeat PET/CT scans at the time of biopsy, of which 10 were interpreted as positive. Conclusions: Consistent with our hypothesis, our results show patients with FN 3 month surveillance PET/CT scans represent a distinct patient cohort, characterized by decreased pre-therapy diagnostic SUV max relative to patients with TP scans. These patients develop late disease recurrences that do not become PET avid until time points beyond 3 months and have longer survival after disease recurrence is documented. Future efforts aimed at reliably identifying this patient group based on pre-therapy clinical characteristics may lead to a decrease in FN scans due to improved patient selection and timing of surveillance PET/CT imaging. Author Disclosure: A. Hoover: A. Employee; University of Iowa Hospitals and Clinics. C. Anderson: A. Employee; University of Iowa Hospitals and Clinics. M. TenNapel: A. Employee; University of Iowa Hospitals and Clinics. P. Goswami: A. Employee; University of Iowa Hospitals and Clinics. Y. Menda: A. Employee; University of Iowa Hospitals and Clinics. J. Buatti: A. Employee; University of Iowa Hospitals and Clinics.
2910 Volumetric Regression Ratio of Tumor and Involved Lymph Nodes After Induction Chemotherapy Predicts the Overall Survival in Head and Neck Cancer O. Elicin,1 M. Schmu¨cking,1 J. Bro¨mme,1 R. Giger,2 D. Rauch,3 D. Leiser,1 P. Ambarcioglu,4 L. Plasswilm,5 A. Geretschla¨ger,1 P. Ghadjar,1 and D.M. Aebersold1; 1Department of Radiation Oncology, Inselspital, University of Bern, Bern, Switzerland, 2Department of ORL, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland,
Poster Viewing Abstracts S569 3
Department of Medical Oncology, Inselspital, University of Bern, Bern, Switzerland, 4Department of Biostatistics, Istanbul University Cerrahpasa Faculty of Medicine, Istanbul, Turkey, 5Department of Radiation Oncology, Kantonspital St. Gallen, St. Galen, Switzerland Purpose/Objective(s): Pre-treatment volumetric evaluation of disease burden predicts outcome in Head and Neck Squamous Cell Cancer (HNSCC). We looked for any predictive value of change in primary tumor and nodal volumes after induction chemotherapy (IC) on oncologic outcome. Materials/Methods: Twenty-three patients with Stage IVA/B non-nasopharyngeal HNSCC treated between 2004 and 2010 with at least one cycle of IC (Docetaxel, Cisplatin and 5-Fluorouracil) and definitive chemo-radiation therapy (CRT) with Cisplatin were retrospectively analyzed. Volumes were calculated separately for primary tumor (Vtm), lymph nodes (Vln) and their sum (Vsum) on computed tomography (CT) images before and after IC. The effect of volumetric changes on loco-regional failure (LRF), distant metastasis (DM) and overall survival (OS) were assessed. Optimal cut-off values for changes in volumes were defined using receiver operating characteristic analyses. Their association with clinical failure and survival were assessed with log-rank tests. p values <0.05 were considered as statistically significant. Results: The cohort had a median age of 57 years (range: 41-73) and a median follow-up of 18.25 months (9-53). Median cycles of IC was 3 (1-5) and the time from the start of first cycle of chemotherapy to start of CRT was 98 days (19-263). Decrease in mean Vtm, Vln and Vsum after IC were statistically significant among each other (p <0.03). Empirical area under the curve (AUC) analyses for conditions; death, LRF and DM revealed optimal cut-off values of Vtm (30.54%, AUC: 87%) and Vsum (35.4%, AUC: 64.55%) only for OS (p <0.05). Among those, a reduction in Vsum more than 35.4% between pre- and post-IC was significantly correlated with better OS (100% vs 56% at 18 months, p <0.03). Conclusions: Volumetric shrinkage in tumor and involved lymph nodes after IC assessed with CT seems to predict overall survival. This methodology may be implemented especially in countries and healthcare settings where resources for Magnetic Resonance Imaging or Positron Emission Tomography are limited. As recently demonstrated in a randomized phase 3 trial IC added to CRT is not superior to CRT alone in the general population of locally advanced HNSCC patients. However, to choose IC for selected cases with bulky disease remains to be an option. The assessment of volumetric shrinkage upon IC might be used to decide whether to offer patients less or more aggressive treatment alternatives after IC. However, strategies like this should be first validated in settings of randomized trials before being used in treatment decision algorithms. Author Disclosure: O. Elicin: None. M. Schmu¨cking: None. J. Bro¨mme: None. R. Giger: None. D. Rauch: None. D. Leiser: None. P. Ambarcioglu: None. L. Plasswilm: None. A. Geretschla¨ger: None. P. Ghadjar: None. D.M. Aebersold: None.
2911 Methods for Analysis and Reporting the Patterns of Locoregional Failure in the Era of IMRT for Head and Neck Cancer: Deformable Image RegistrationeBased Quality Assurance Workflow A.S. Mohamed,1 M. Awan,2 E. Kocak,3 B.M. Beadle,4 M.E. Kantor,5 G.B. Gunn,1 A.S. Garden,4 D.I. Rosenthal,1 and C.D. Fuller5; 1University of Texas MD Anderson Cancer Center, Houston, TX, 2George Washington School of Medicine, Washington, DC, MD, 3Istanbul University, Istanbul, DC, 4University of Texas MD Anderson Anderson Cancer Center, Houston, TX, 5University of Texas MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): The accurate and specific reporting of the exact site of loco-regional failure after intensity modulated radiation therapy (IMRT) of head and neck cancer in addition to the dose given to this site is mandatory to identify the possible causes of failure. Our aim is to develop a workflow methodology to accurately define the area of recurrent/ persistent disease relative to the original planning target volumes (TVs) and prescribed radiation doses using a validated deformable image registration (DIR) software.