max dose =104.5%; PTV54Gy V100% = 95.6%, V93% = 100%, max dose = 104.6%; liver: V20Gy = 44.3%, V30Gy = 21.9%; stomach: V30Gy = 21.6%, V45Gy = 12.2%; small bowel: mean = 13.1Gy, V45Gy = 12.3%, V30Gy = 18.7%; ipsilateral kidney: V18Gy = 36.1%; contralateral kidney: V18Gy = 22.3%; spinal cord: max dose (to .1cc) = 43.1Gy. Only 2 patients (8.3%) suffered acute toxicity.grade 2 during chemoradiation. These 2 patients required IV fluids for dehydration. Median weight loss during chemoradiation is 4 lbs. or 3%. The median change in performance status is 0. Median overall survival is 12.2 mo, median PFS is 9.1 mo, and 6-mo PFS is 80% based on intent-to-treat analysis. Conclusions: This phase II study demonstrates that IMRT with concurrent capecitabine after multi-agent induction chemotherapy with Gem/Ox/Cet is well tolerated with relatively mild acute toxicity. Author Disclosure: D.T. Marshall, None; P. O’Brien, None; B. Hoffman, None; E. Garrett-Mayer, None; U. Chaudhary, None; A. Brisendine, None; B.D. Jones, None; L.E. Terwilliger, None; K. Cranford, None; N. Esnaola, None. 2193 Treatment Results of Early Esophageal Cancer: Is Elective Nodal Irradiation Effective for Tumor Control and Survival? J. Fukada 1 , N. Shigematsu 1 , H. Takeuchi 2 , T. Nakahara 1 , Y. Kitagawa 2 , T. Ohashi 1 , E. Kunieda 1 1 Department of Radiology, Keio University School of Medicine, Tokyo-to, Japan, 2 Department of Surgery, Keio University School of Medicine, Tokyo-to, Japan Purpose/Objective(s): Latent lymph node metastasis cannot be negligible even in early stage esophageal cancer. Sentinel lymph node (SLN) concept holds promise in the treatment of such cancer. We retrospectively reviewed the treatment results based on SLN mapping to determine the usefulness of elective nodal irradiation. Materials/Methods: Between 2001 and 2006, 76 patients with clinically staged T1N0-1 esophageal cancer received definitive radiation (n = 26) or concurrent chemoradiation (n = 50). Eligible patients with T1N1 were defined as having lymph node smaller than 1 cm in diameter. SLN mapping was performed in 29 patients diagnosed as having invasion beyond submucosal layer. Sixty patients had submucosal disease and remaining 16 patients had disease localized to lamina propria mucosa. Radiotherapy was per- formed by 6MV x-ray, 2 Gy per day, 5 times a week. Forty-four patients were treated with 5-FU/Cisplatin-based chemotherapy and 6 patients with weekly low-dose docetaxel. Radiation was delivered to the local esophageal lesion with margin in patients in whom SLN mapping was not performed. Elective nodal irradiation was delivered in patients with SLN mapping. After 46 Gy, radiation field was limited to the involved lesion avoiding spinal cord with a maximum total dose of 60 Gy. Evaluation was done by follow- up gastrointestinal fiberscopy and chest-abdominal computed tomography. Statistical analyses were calculated according to Kaplan-Meier method and a log-rank test was applied. Results: The median follow-up was 47 months (range, 3-89). Initial complete response was achieved in 65 patients (86%). The 4- year overall survival rate was 76% in the SLN-mapping group and 83% in the local irradiation group. In-field, regional, and distant lymph node metastases were found in 2, 0, and 3 patients, respectively, in the SLN-mapping group and in 1, 2, and 1 patient, re- spectively, in the local irradiation group. Esophageal local recurrence occurred in 20 patients (26%), and 14 patients were rescued by salvage endoscopic mucosal resection. Salvage esophagectomy was performed in 2 patients. Overall esophageal-sparing rate was 79%. In the SLN-mapping group, 11 patients showed positive SLN in the supraclavicular region and 5 patients in the peri- gastric region. In other patients, proximal injected site was diagnosed as positive SLN. Conclusions: Response and survival rates of radiotherapy or chemoradiotherapy were acceptable. No regional lymph node recur- rence occurred in the SLN-mapping group though, only two cases with regional lymph node recurrence were observed in the local irradiation group. Further study is needed to warrant elective nodal irradiation. Patients should be closely followed up by gastro- intestinal fiberscopy to detect local recurrence. Author Disclosure: J. Fukada, None; N. Shigematsu, None; H. Takeuchi, None; T. Nakahara, None; Y. Kitagawa, None; T. Ohashi, None; E. Kunieda, None. 2194 Renal Function following Abdominal Chemoradiotherapy for Gastrointestinal Malignancies in Elderly Patients K. Salerno May, M. Fakih, N. Khushalani, R. Chandrasekhar, G. Wilding, L. Park, L. Flaherty, R. Russo, R. Iyer, G. Yang Roswell Park Cancer Institute, Buffalo, NY Purpose/Objective(s): There is limited literature available on renal tolerance and progressive dysfunction in elderly patients following modern treatment of gastrointestinal malignancies. This study assessed the effects of abdominal chemoradiation on renal function in the elderly. Materials/Methods: Patients 65 years of age or older who received concurrent chemotherapy and CT planned conformal radiation (RT) to the abdomen between 2002 and 2008 were identified to evaluate change in renal function. Biochemical and imaging data were obtained prior to and after RT in 6 month intervals. Renal function was assessed by serum creatinine and creatinine clearance (CrCl) using the Cockcroft-Gault formula. Kidney size was defined by craniocaudal measurement on CT images. The primarily irradiated kidney (PK) was the kidney that received the greater mean kidney dose (MKD). Renal toxicity was assessed by decrease in CrCl and scored using the RTOG/EORTC Late Radiation Morbidity Scoring Schema. Statistical analysis for categorical variables was performed using Fisher’s exact test. The Wilcoxon non-parametric test with exact p-values was used for continuous variables. Results: Of 81 patients, median age was 72 years (range 65-90), 42% were $ 75 years of age and 54% were males. Primary disease sites included pancreas and periampullary (70.4%) and gastric and gastroesophageal junction (28.4%). Median radiation dose was 50.4 Gy (range 12.6-55.8 Gy). The MKD for the PK, non-PK, and bilateral kidneys was 18.1 Gy, 7.2 Gy, and 12.7 Gy each. The majority of patients received 5-fluorouracil, capecitabine, and/or gemcitabine based regimens. One year following completion of RT, CrCl decreased from 71.79 ml/min preRT to 64.11 ml/min (p \0.0001). Creatinine did not change significantly over the same time period. Mean kidney size of the PK decreased from 100.48 mm preRT to 98.42 mm (p = 0.0373). Compensatory hypertrophy of the non-PK was not seen. Age ( \75 or $ 75 yrs), gender, hypertension, diabetes, smoking, chemotherapy, and preRT CrCl were not associated with $ grade 2 renal complications (decrease in creatinine clearance.25%) at 12 months postRT. Percent volumes S268 I. J. Radiation Oncology d Biology d Physics Volume 75, Number 3, Supplement, 2009