4DCT-Based Target Volumes in the Definition of Radiation Treatment Planning in Primary Thoracic Esophageal Cancer

Poster Viewing Session E155

Volume 93  Number 3S  Supplement 2015 AUCZ0.974) were lower in the effective group (nZ17) than in the ineffective one (nZ6) and highly successful in differentiating the two different CRT sensitivity groups. Conclusion: The three-dimensional texture parameters of pretreatment ADC maps may be a predictor for treatment response in patients with ESCC. Author Disclosure: B. Li: None. Y. Mao: None. Z. Li: None.

2393 Influence of Body Mass Index (BMI) on Colorectal Cancer Mutation Status S.C. Kamran,1 A.L. Russo,2 D.R. Borger,2 J. Szymonifka,2 E.L. Kwak,2 J.W. Clark,2 L.S. Blaszkowsky,2 D.P. Ryan,2 J.N. Allen,2 J.Y. Wo,3 A.X. Zhu,2 A. Iafrate,2 K.M. Haigis,4 and T.S. Hong3; 1Harvard Radiation Oncology Program, Boston, MA, 2Massachusetts General Hospital, Boston, MA, 3Massachusetts General Hospital, Harvard Medical School, Boston, MA, 4Beth Israel Deaconess Medical Center, Boston, MA Purpose/Objective(s): Mutational status in colorectal cancer (CRC) impacts response to EGFR inhibition, prognosis, and may affect response to chemoradiation. While obesity correlates with increased colorectal cancer risk, it is less clear if obesity increases the predilection for certain genotypes. The purpose of the following study was to determine the influence of BMI on mutational status, and whether that influenced overall survival. Materials/Methods: Patients with colorectal cancer were retrospectively analyzed with IRB approval. Genotyping was performed for >150 mutations across 15 commonly mutated cancer genes including NRAS, KRAS, PIK3CA, Braf, and PTEN as part of their clinical management and recorded in the medical record. Patient characteristics, including BMI, was extracted from the medical record. BMI was captured at time of diagnosis. Using the NIH definition of 25 as overweight, BMI was analyzed as a dichotomous variable, 25 or <25. Genotype stratified by dichotomized BMI was used to determine a hazard ratio for overall survival. Results: 123 patients were identified with both mutational status and BMI. Median age was 57 (range 31-84). 66 (54%) were male. 93 (76%) presented with stage IV disease, 35 (28.4%) with rectal cancer, 60 (49%) were non-smokers. 86 patients had a BMI 25, and 37 patients had a BMI < 25. There was no difference in age, gender, stage at presentation, or percentage of patients with rectal cancer. KRAS was found to be significantly associated with BMI 25 (OR 3.15 (95% CI 1.29-7.68), p<0.012). BMI 25 was not significantly associated with having a higher stage at initial presentation, nor was it associated with a significantly worse PFS or OS (PFS HR 1.11 (95% CI 0.71-1.74); OS HR 1.28 (95% CI 0.79-2.08); NS). Conclusion: BMI 25 was found to be significantly associated with KRAS mutations. These data are concordant with other reports.

Poster Viewing Abstracts 2393; Table 1 mous BMI ( 25 vs < 25) NZ123

Mutation odds ratios for dichoto-

BMI  25 odds ratio (95% CI) p-value

NRASd4 (3.3%) mutations 0.13 (0.01, KRASd48 (39.0%) mutations 3.15 (1.29, PIK3CAd16 (13.0%) mutations 1.34 (0.40, Brafd15 (12.2%) mutations 1.21 (0.36, PTENd1 (0.8%) mutations Not estimable Any mutationd88 (71.5% mutations) 1.58 (0.69, Stage 4 at presentationd93 (75.6%) 0.80 (0.32,

1.33) 7.68) 4.46) 4.08) 3.62) 2.02)

0.086 0.012 0.636 0.759 NA 0.283 0.640

Author Disclosure: S.C. Kamran: None. A.L. Russo: None. D.R. Borger: None. J. Szymonifka: None. E.L. Kwak: None. J.W. Clark: None. L.S. Blaszkowsky: None. D.P. Ryan: None. J.N. Allen: None. J.Y. Wo: None. A.X. Zhu: None. A. Iafrate: None. K.M. Haigis: None. T.S. Hong: None.

2394 Geometrical Evaluation of 3DCT-Based and PET/4DCT-Based Target Volumes in the Definition of Radiation Treatment Planning in Primary Thoracic Esophageal Cancer Y. Guo,1 J. Li,2 Q. Shao,3 and Y. Li4; 1Shandong Cancer Hospital, Jinan, China, 2Shan Dong Cancer Hospital, Jinan, China, 3Shan dong Cancer Hospital, Jinan, China, 4School of Medicine, Shandong University, China, Jinan, China Purpose/Objective(s): To compare planning target volume (PTV) defined on PET combined with 4DCT to PTV based on 3DCT and 4DCT. Materials/Methods: Eighteen (18/30) esophageal cancer patients who underwent contrast-enhanced 3DCT, 4DCT and 18F-FDG PET-CT thoracic simulation with SUVmax2.0 of the primary volume were enrolled. CTV3D was formed on 3DCT by adding a margin of 30mm in cranial-caudal direction and 5mm in transversal direction. PTV3D was defined using a 10mm margin to CTV3D; CTV4D was obtained by fusion of CTV from ten phases of 4DCT. A 5mm margin for setup errors to CTV4D was to form PTV4D. BTVPET was generated with the assumption that motion was captured in PET images using a thresholding method: 20% SUVmax. CTVPET 4DCT was calculated by the union of BTVPET and CTV4D, and a 5mm margin to CTVPET 4DCT was used to form PTVPET 4DCT. The geometrical differences of the targets were evaluated. Results: Statistically significant differences were observed among CTV3D, CTV4D and CTVPET 4DCT (CTVPET 4DCT> CTV4D > CTV3D, pZ0.000-0.038). PTV3D, PTV4D, and PTVPET 4DCT also differed significantly from each other (PTVPET 4DCT> PTV4D > PTV3D, pZ 0.000-0.048). The DI of PTV3D in PTVPET 4DCT was significantly larger than that of PTV3D in PTV 4D (PZ0.042). There were no significant differences between the DI of PTV4D in PTV3D and PTVPET 4DCT in PTV3D (PZ0.118). Conclusion: As demonstrated by the assessment of the geometrical differences in PET/4DCT-based and 3DCT-based PTV, PET/4DCT could affect not only the volume of PTV but also its shape. The use of PET/ 4DCT may be better for delineating PTV by tailoring the target volume to the lesion motion than 3DCT or 4DCT alone in primary esophageal cancer. Author Disclosure: Y. Guo: None. J. Li: None. Q. Shao: None. Y. Li: None.

2395 Stereotactic Body Radiation Therapy for Liver Oligo-Recurrence From Variable Tumor Y. Cha, M.S. Kim, C.K. Cho, H. Yoo, W.I. Jang, Y.S. Seo, J.K. Kang, and E.K. Paik; Korea Institute of Radiological and Medical Sciences, Seoul, South Korea Purpose/Objective(s): Recent technology of diagnosis has increased prevalence of oligo-metastatic patients. Among them stereotactic body radiation therapy (SBRT) to oligo-recurrence showed high local control but also promising overall survival. Though surgery is most common local modality for liver oliog-recurrence, above 80% of these patients are unresectable. An effective and safe local modality option is necessary for these patients. We evaluated outcomes and toxicity for patients with liver oligo-recurrence treated with SBRT. Materials/Methods: Seventy-two patients with liver oligo-recurrence from 2002 to 2013 were treated by SBRT consecutively. Among them, 17 patients excluded; un-controllable distant metastases in 9 patients and immediate follow-up loss after SBRT in 8 patients. We retrospectively assessed overall 55 patients with 77 lesions. Primary lesions of all patients were controlled, the patients with stable lesions in another site in 28 patients. The most common primary site was colorectum in 36 patients followed by the stomach 6 patients, and other 13 patients. The tumor volume was calculated by adding up total GTV of each patient. The median volume was 20 cc (0.7-721.2 cc). Thirty-eight (69%) of the patients had a single lesion. Total SBRT dose was from 30 to 60 Gy (median 48 Gy) with