P-709 Determining optimal treatment volume margins in moving lungtumours

Posters t Radiotherapy (<150 cm 2) in cont]'ast to no survivors in large port group (>160 crn2) where all five patients died within six months Six of eight patients who received high dose radiation in Plan A (6000 7000 cGy) are currently alive There were no survivors among the four patients receiving low dose radiation in Plan A A similar tTend (dosa/porUsurvival relationship) was found in Plan B patients as well This study demonstrated that instltu'dng large port radiation predicts dethmental outcomes regardless of tumor stages Conclusions: The radiation onoologist could e~pact a poor prognosis if large port placement is necessary in order to adequately cover the mediastlnum and tumor lesions. The smaller the radiation ports, the better the therapeutic outcomes. We should explore a new local radiation therapy using a small radiation port along with chemotherapy in order to study the feasibility of eliminating prophylactic mediastinal irradiation for microscopic tumor deposits. Elimination of mediastlnal irradiation will facilitate utilr~atlon of small port therapy, possibly leading to enhancement of favorable therapeutic outcomes by preventing the detrimental risk of morbidity and mortality created by large port irraclation [P--70~ Trsabnent outcomes of three-dimensional conforrnal radiotherapy for non-emall cell lung cancer M. Cho ~'4. S. yeel. K. KJmI . S. Kim 2'4. S. Lim 3. J. Kim 1'4. 1Departments

ot Radlabon Onco/ogy, Chungnam Nattonal Umvers~ty Hospital, Japan: 2Departments or Internal Medicine, Chungnam Na~onal University Hospital, Japan, 3Departments of Chest Surgery, Chungnam Nabonal University Hosptal, Japan, 4Cancer Researeh lnsbtute, Chmgnam National Untwrsity, Japan Background: To evaluate our instltu'don's expedenoe using three-dimensional eenformal radiotherapy (3D-CRT) in conjunction with induction chemotherapy for the t]-eatment of non small cell lung cancer (NSCLC). Methods: Between November 1998 and March 2003. 24 patients of histologically proven NSCLC treated with induction chemotherapy and following 3DCRT were retrospectively reviewed. The patient charactenstios were as follows: stage IB in 1. stage lib in 1. stage Ilia in 9. stage IIIB in 13; median age 69 years (range 42-79 years); male in 22. female in 2; squamous cell carolnoma in 18. adeneearclnoma in 4. adenosquamous cell carolnoma in 1. undifferentiated large cell carcinoma in 1 Twenty two patients received induction chemotherapy be~re radiation therapy The majority of chemotherapy regimen consisted of cisplatln and gemcitabine Radation was delivered with conventional anteropostenor and posteroanterior fields until 36 Gy and then 3DCRTwas performed The mecian total dose was 70 2 Gy The mecian follow-up time was 17 months (range 4 ,sg months) Results: The median overall survival period was 17 months One. two and thre~year overall survival rates were 66.7%. 34.8% and 27.8%. respectively The median progressior-, free survival period was 20 months. One. two and thre~year progression free survival rates were 64.,5%. 39.3% and 19.7%. respectively. The prognostic factors for overall survival by unlvarlate analysis were age(~<70), histology. T stage, and chemotherapy response. In histology. the squamcus cell carclnema showed better overall survival than others. Acute to~citles which were evaluated by RTOG crltena included two cases of grade 2 esophagus and three cases of grade 3 lung toxicity Conduslons: We could increase the radiation dose without significant increment of acute toxicitiea by using 3D-CRT Also it seems to be a safe. well-tolerated and effective t]-eatment modality ~r NSCLC

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Deterrnlnlng optimal treatment volume marglne In moving lung tumours [3. Cho. A Bezjak. G Kane. D Payne. A Sun Department or Radialon Oncdogy, Princess Margaret Hospital, University of Toronto, Toronto, Canada

Ba-'kground: The concept of Planr~ng Target Volume (PTV). Clinical Target Volume (CTV) and Treatment Volume (TV=PT'v'+margin for beam penumbra). defined in International Commission on Radiation Units and Measurements (ICRU) Report ,50. are well recognized and widely accepted More recently. ICRU Report 62 intTeduced the Internal Margin (IM) to account ~ r physiological sources of errors such as breathing and recommends that margins should be defined such that it reflects the real dose the moving CTV receives For lung tumours, the "IV margin (TVM) can be pa~cularty large due to increased lateral scatter in less dense lung tissue The purpose of the planning study is to determine the optimal 0.e. tightest) P4 margin in moving lung tumours. aceeuntlng for beam penumbra, respiratory motion and the true moving CT'v' absorbed dose. Methods: An idealized rectangular phantom ( 2 0 x 1 5 x 1 5 c m ~ = H x W x L ) consisting of a 3cm diameter spherical CP4 surrounded by lung eguivalent media (p 0 2 g/cm 3) was generated The IM was 3 cm (pe~k to t]'ough) The PTVwas defined as the CTV+IM Parallel-opposed pair beams, using mutlileaf collimators conformed around the PTV with uniform treatment volume margins (i.e. P4 minus PTV) varying from 0.5 to 2.0 cm. as seen from beam's~ye~iew. were used. The centre of the CTV was prescnbed to 100%. Minimal Tv' margins for clfferent dose~olume target constraints were analysed using dos6~volume histograms for the moving C W and the PTV.

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Results: A 14mm TVM was necessary to ensure 99% of the moving CT'v' receives at least g,5% of the prescribed dose while a 19mm was needed to ensure identical coverage for the PTV An 8. mm T'v'M was necessary to ensure 95% of the moving CTV receives at least 93% of the preschbed dose throughout respiration while a 13 mm was needed to ensure identical coverage for the PTV The T'v'M depended on the sthngenoy of the dosevolume constraint The irradated lung volume (relative volume receiving ,50% prescribed dose) vaded from 12% (TVM ,smm) to 26% (TVM 2Omm) COrlCluslons: Relaxing the dose~olurne constz'aints to mantain adequate moving CTV (as opposed to PTV) coverage can result in tighter treatment volume margins by approximately 5ram. Further work in defining optimal treatment margins in moving lung tumours is necessary. Polymorphlem of NAD(P)H:qulnone oxldoroductase (NQO1) pro187eer and prognosis of non-small cell lung cancer alter radiation therapy E. Choi I . H Park 3.S Song ~.S Yoon ~.S Lee 1.S Sbln ~.J Kim 4 . Y H o n g 4. J. Lee 2. ~Departm~nt of Red/atton Onco/ogy, Asan Medrcal Center, College

of Medicine, University of U/san, Seoul, South Korea, 2Department of Internal Medicine, Asan Medical Center, Collage or Medicine, University or U/san, Seoul, South Korea: 3D~partment of Mlcrot~ology, Cetlege of Me~cme, tnha University, tncheon, South Korea, 4Department or Preventive Me~cine, Seoul Nabone/Universi~ College of Medicine, Seoul, South Korea Backgrounds: NAD(P)H:quinone oxidoreductase 1 (NQO1) has been known to function on reduction of oxidative status am a c~/tosolic flavoenzyme that catalyzes the election reduction of subst]'ates. It was reported to play a role in the prognosis of lung cancer patients tTeated with chemotherapy We studied to assess that the NQO1 pro187sor polymorphism is associated with progressionfree or overall survival of non-small cell lung cancer (NSCLC) patients treated with radiotherapy Methods: One hundred and ninety-nine patients with squamous cell carcinoma or adenocarcinema of stage I-III non-small cell lung cancer were recruited at the Asan Medical Center from 2000 to 2003 We determined the genotypas of the NQO1 gene by single base primer extension assay using SNapShot Kit TM with blood samples ~r all patients Kaplan4Vleier survival curves and the Iograr~ test were used to analyze the effects of genetypes on survival Hazard ratios were calculated using the Cox-proportional hazard model Reaulte: Patients carrying pro/pro or pro/ser genetypes had a significantly longer preogression-free survival than those carrying sar/ser genetypa (P 0 033). but not significantly for overall survival (P 0 4,52) Particularly. histological types showed a significant effect on progression free and overall survival (P = 0.004 and P = 0.051). Both progression free and overall survival was longer for patients carrying squarnous cell carolnoma than those carrying adencoarolnoma Conclusions: NQO1 polymorphism could be used as prognostic marker for non small cell lung cancer patients treated with radiotherapy. ~1]

CyberKnlfe ® rrsmefaes Image-guided radlosurgery with the Synchrony TM motion tracking module In the deflnRIve tTeetment

of small perlphersl lung tumors: The Georgetown University Hospital early expedence R. Collins. S. Malik. M. Merge/is. M. Marshall. C. Jamis Dew. S. Dieterlch. M. Lundsten. D. McRae. C. Reichner. E. Anderson. Georgetown Un/vererty Hospital, Wa~/ngton, DC, USA Background: The management of eady stage NSCLC is a challenging problem The tumors are aggressive and the patients are typically frail Radical surgery is an effective therapy However. a significant number of patients are not surgical candidates Conventional irradiation has been utilized with limited success due to poor local tumor control and significant pulmonary tmdcity Radioablation has been evaluated recently with promising results. However. broader aoceptance has been slowed by its variable, tedious application. The CyberKnife system has been successfully utilized to t]-eat tumors anywhere in the body. With the Synchrony TM Motion Tracking Module. tumors that are influenced by respiratory motion may be treated quickly, accurately and effectively with minimal patient discomfort. This is accomplished by utilizing a continually updated model predicting target location. This model is generated by the use of surface visible red light emit'ring t]'acking markers as continuously sampled by a camera array and fiducials as episodically imaged by the CyberKnife x-ray targeting system Methods: At Georgetown University Hospital. the irttlal patients with small (<,5 cm). inoperable solitary peripheral lung tumors have completed treatment with the CyberKnife system u'dlizing the Synchrony module Multiple fiducials were placed proximal to the tumors utilizing CT guidance The patients had a treatment planning CT completed during a breath hold in a supine treatment pos~]on with vacuum bag immobilization. The tumor volumes were contoured utili,,tng lung windows. A t]-eatment plan with a 5 mm margin was generated. In preparation for t]'eatment, three visible red light emitting markers were placed on each patient's antenor torso. Each patient recerved three large fractions