Proceedings of the 52nd Annual ASTRO Meeting S331

Materials/Methods: Forty-four patients with rectal adenocarcinoma were investigated. LAT1 expression was immunohisto-chemically evaluated using pre-treatment biopsies. The total radiation dose was 40-50 Gy and chemotherapy consisted of 5-FU(250 mg/m2 per day) and leucovorin (25 mg/m2 per day) administered by continuous infusion in the night for 5 days a week inthe 1st, 3rd, and 5th weeks of radiation. Hyperthermia was performed for 2-5 sessions once a week with 8 MHz radiofrequencycapacitive heating equipment. The operation was performed after 2-3 months following HCRT and each resected specimen wasgraded by histological criteria of the Japanese Classification of Colorectal Carcinoma.

Results: A positive LAT1 expression was recognized in 50.0 % (22/44). Resected specimens were shown that grade 1a, 1b, 2, and3 were 5, 10, 20, and 9, respectively. Patients were divided into 2 groups; grade 2 and 3 were good responders (n = 29) and grade 1aand 1b were poor responders (n = 15). Of 29 patients with good responders, 18 patients (62.1%) had LAT1 negative expression and11 (37.9%) LAT1 positive expression, demonstrating statistically borderline (p = 0.054). There was no significant difference in thesurvival according to LAT1 expression.

Conclusions: The rectal cancer patients with LAT1 expression showed poor response to HCRT.

Author Disclosure: T. Ebara, None; K. Kaira, None; M. Shioya, None; T. Asao, None; T. Takahashi, None; H. Sakurai, None; Y.Kanai, None; H. Kuwano, None; T. Nakano, None.

2286 Stereotactic Radiotherapy for Medically Inoperable Pancreatic Cancer

M. M. Haley, M. Ajlouni, S. Ryu

Henry Ford Health System, Detroit, MI

Purpose/Objective(s): Surgery is the only known cure for resectable pancreatic cancer, however it is estimated that only about23% of those with local disease have their tumors resected. This leaves only chemotherapy, radiation, or a combination as a localtherapy alternative. Several studies have examined the outcome of hypofractionated stereotactic body radiotherapy (SBRT) onlocally advanced pancreatic cancer. The aim of this study is to report outcomes of medically inoperable pancreatic cancer patientstreated with SBRT.

Materials/Methods: Eleven medically inoperable patients with clinical stage I or II pathologically confirmed pancreatic adeno-carcinoma were included on the IRB approved study. All patients were treated with SBRT as a sole modality. Patients receiveda total of 3, 5, or 6 fractions, fraction size of 6, 7, or 12 Gy, and a total stereotactic dose of 30, 35, or 36 Gy. Patients were treatedto isodose line 90, 95, 97, or 98. Patients were treated using 4D CT treatment planning and an internal target volume (ITV). Theplanning treatment volume (PTV) ranged from 24.091 cc to 82.529 cc.

Results: Median age of all patients was 82 years (range, 80-90). Four patients had previous malignancies (3 prostate, 1 non smallcell lung cancer). Local recurrence alone as first site of failure was 27.7%, local recurrence plus distant metastasis as first site offailure was seen in 27.7% of patients, and distant mets alone was seen in 9% of patients. 36.3% of patients had no recurrence, witha median follow-up of 3.7 months (range, 1.7-7.8 months) for those without recurrence. Of those patients that progressed, mediantime to progression was 4.3 months. Median survival from date of diagnosis to date death was 7.4 months (range, 3.3-12.8 months).Median progression free survival was 4.1 months (range, 1.7-7.8 months). Two patients experience grade 3 late toxicity with gastriculcers that resolved. One patient experienced acute toxicity of loss of appetite, weakness, and fatigue. No other toxicities were seenin all other patients.

Conclusions: Hypofractionated SBRT may provide an alternative palliative option for medically inoperable pancreatic cancerpatients with reasonable local control and low toxicity. Further follow-up is necessary and the optimal dose/fractionation forSBRT requires further study.

Author Disclosure: M.M. Haley, None; M. Ajlouni, None; S. Ryu, None.

2287 Treatment of Low-lying Rectal Adenocarcinoma with Californium-252 (252Cf) Neutron Intracavitary

Brachytherapy(ICBT) and External Beam Radiotherapy (EBRT): The Three Years Result for 130Patients(Phase II Trial)

X. Lei

Da-Ping Hospital, Chong-Qing, Chongqing, China

Purpose/Objective(s): To research the three years result for 130 rectal adenocarcinoma patients treated by radiotherapy (RT) aloneusing a combination of 252Cf ICBT and EBRT with or without 252Cf rectal interstitial implant (RIT).

Materials/Methods: From Dec 2006 to Oct 2008, 130 patients diagnosed by endorectum biopsy and staged with endorectalultrasonography B were accrued into this trial. Patients had to have T1-T3 (T1, 24; T2 [T2a, 6] 46; and T3,60), N0-N1, M0low-lying tumor (less than 6 cm from the anal verge, involving #2/3 the circumference). The median age was 59.5 yearsold. Before the RT, the 252Cf dose calibration for rectal cancer using Relative Biological Effectiveness and the manufactureof off-axis four channel intrarectal applicator, which was 3 and 3.5 cm for the diameter respectively, were implemented. T1 pa-tients were treated with ICBT alone. Six T2aN0 patients were treated with ICBT plus RIT (15-17 Gy/f) without EBRT. The RTof T2b and T3 patients began with EBRT, 40 T2 patients were irradiated to 37.4-39.1 Gy (2.2-2.3 Gy/f/d) with A-P field (cen-tered on the tumor ,7 � 10 cm), 60 T3 patients were irradiated to 41.8-42 Gy (2.1-2.2 Gy/f/d) with A-P whole pelvic field . Thereference point of ICBT was defined on the mucosa surface. The total does were 58-62 Gy/4f, 14-15 Gy/f; 56-59 Gy/4f, 14-15Gy/f; 43-45 Gy/3f, 13-15 Gy/f, and 42-44 Gy3f, 12-15 Gy/f for T1, T2a, T2b, and T3 patients, respectively. After a 4-weekinterval completed the combination ICBT and EBRT, RIT was delivered at 15-19 Gy/f to the residue tumor for 4 T2 and 18T3 patients.

Results: The calibrated 252Cf total dose of 41�45 Gy was equivalent to 71�76 Gy. The acute toxicity was moderate. After the RT,all the lesions of T1, most of T2 and 50% T3 regressed completely. About 25% lesions of T3 presented with white mucosa layer onthe surface, but the area of them reduced gradually. Other 25% lesions of T3 also presented with them on the surface, but the areaincreased gradually, the surface manifested the scattered black spot. It suggested that the deficient deep dose and this classification

S332 I. J. Radiation Oncology d Biology d Physics Volume 78, Number 3, Supplement, 2010

of tumor were not sensitive enough to RT. The 3-year’s local control rate was 80%, 90%, 79%, and 76% for T1, T2, and T3, re-spectively. The overall survival rate was 74%, 83%, 78%, and 66% for T1, T2, and T3, respectively. The progression-free survivalrate was 68%, 80%, 69%, and 59% for T1, T2, and T3, respectively. The G2 late complication (rectal bleeding, frequent urgency)rate was 19%, 12.8%, 19.5%, and 21% for T1, T2, and T3, respectively. No $ G3 late complication occurred.

Conclusions: Our method is perspective due to the use of off-axis four channel applicator solved the normal tissue protection dif-ficulties.

Author Disclosure: X. Lei, None.

2288 Protons Offer Reduced Normal Tissue Exposure for Patients Receiving Postoperative Radiotherapy (RT)

for Resected Pancreatic Head Cancer

R. Nichols1, S. Huh1, K. Prado2, B. Y. Yi2, N. K. Sharma2, M. W. Ho1, B. S. Hoppe1, W. M. Mendenhall1, N. P. Mendenhall1,

W. F. Regine2

1University of Florida Proton Therapy Institute, Jacksonville, FL, 2University of Maryland, Baltimore, MD

Purpose/Objective(s): Determine the potential role for adjuvant proton based radiotherapy (RT) for resected pancreatic headcancer.

Materials/Methods: From 6/08 to 11/08, 8 consecutive patients with resected pancreatic head cancers underwent optimized in-tensity modulated radiotherapy (IMRT) treatment planning. IMRT plans utilized between 10 and 18 fields and delivered 45 Gy toan initial PTV with an additional 5.4 Gy boost to a reduced PTV volume. PTVs were defined according to the US Intergroup/RTOG 9704 RT guidelines. 95% of PTV volumes received 100% of the target dose and 100% of the PTV volumes received95% of the target dose. Normal tissue constraints were as follows: Right Kidney V18 Gy to \ 70%; Left Kidney V18 Gy to\ 30%; Small Bowel/Stomach V20 Gy to \ 50%, V45 Gy to \ 15%, V50 Gy to \ 10%, V54 Gy \ 5%; Liver V30 Gy to\ 60%; Spinal cord maximum to 45 Gy. Optimized 2 to 3 field 3D conformal proton plans were retrospectively generated onthe same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans.IMRT and proton plans were then compared. A Wilcoxon paired T-test was performed to compare various dosimetric pointsbetween the 2 plans for each patient.

Results: All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms ofPTV coverage. Proton plans offered significantly reduced normal tissue exposure over the IMRT plans with respect to: mediansmall bowel V20Gy (15.4% with protons vs. 47.0% with IMRT - p = 0.03); median gastric V20 Gy (2.3% with protons vs.20.0% with IMRT - p = 0.03); and median right kidney V18 Gy (27.3% with protons vs. 50.5% with IMRT - p = 0.02).

Conclusions: By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicity ofpostoperative chemoradiation in this setting.

Author Disclosure: R. Nichols, None; S. Huh, None; K. Prado, None; B.Y. Yi, None; N.K. Sharma, None; M.W. Ho, None; B.S.Hoppe, None; W.M. Mendenhall, None; N.P. Mendenhall, None; W.F. Regine, None.

2289 18F-FDG Uptake by Primary Tumor as a Predictor of Lymph Node Involvement in Clinical N0 Patients with

Esophageal Squamous Cell Carcinoma

W. Q. Zhu1, M. H. Li1, X. R. Sun2, X. D. Sun1, L. G. Xing1, L. Kong1, G. R. Yang1, J. M. Yu1

1Department of Radiation Oncology, Jinan, China, 2Department of Nuclear Medicine, Jinan, China

Purpose/Objective(s): Lymph node involvement is an important factor in the planning of therapeutic strategies, particularly sur-gical resection method and radiation targeted volume delineation in patients with early-stage esophageal squamous cell cancer. The18F-FDG uptake within the primary lesion correlates with aggressiveness on PET studies. The more metabolically active the tumor,the more aggressive are the findings. The aim of this study was to determine whether 18F-FDG uptake of the primary tumor is a pre-dictor of lymph node metastasis in esophageal squamous cell cancer.

Materials/Methods: Thirty-one patients with esophageal cancer were studied. All patients underwent a thoracotomy within1month of the 18F-FDG PET study. The degree of 18F-FDG uptake in the primary tumor was correlated with the incidence of lymphnode involvement. Multivariate analysis was performed with logistic multivariate analysis to assess the joint effects of the variables(age, gender, tumor length, T stage, differentiation grade, 18F-FDG uptake and so on) on lymph node involvement

Results: Lymph node involvement was found in 1/7, 6/13, and 7/10, respectively, of the patients classified in the low-grade, mod-erate-grade, and high-grade group. The mean SUVmax of lymph node metastasis group is 12.97 ± 6.00 with 17.77 ± 4.54 in thewithout lymph node metastasis group (p = 0.02). Multivariate analysis showed that 18F-FDG uptake was a significant factor forlymph node involvement. All the four patients in the high-grade group who are considered to have lymph node metastasis in termsof the imaging of lymph nodes themselves measured by PET/CT have lymph node metastasis in the fact. Similarly, all the six pa-tients in the low-grade group who are currently no lymph node metastasis measured by PET/CT are no metastasis by pathology. Incontrast, of the patients in the low-grade group whose lymph nodes were positive by PET/CT, lymph node involvement was foundin 1/2. And of the patients in the high-grade group whose lymph nodes were negative by PET/CT, lymph node involvement wasfound in 4/20.

Conclusions: A significant correlation exists between the incidence of nodal involvement and 18F-FDG uptake by the primarytumor in early-stage esophageal squamous cell carcinoma. Patients with a low 18F-FDG uptake in the primary lesion had a signif-icantly decreased risk of lymph node metastasis than did those with a high 18F-FDG uptake. So for diagnosis of lymph node me-tastasis, the conventional examination is not enough, PET/CT is needed. And the value of primary lesion SUVmax is also the factorsthat should not be ignored in addition to considering the imaging of lymph nodes themselves. In patients with esophageal squamouscell carcinoma, 18F-FDG uptake by the primary tumor is a strong predictor of lymph node metastasis.

Author Disclosure: W.Q. Zhu, None; M.H. Li, None; X.R. Sun, None; X.D. Sun, None; L.G. Xing, None; L. Kong, None; G.R.Yang, None; J.M. Yu, None.