Predictors of Survival in Yttrium-90 Radioembolization of Hepatic Malignancies With Resin Microspheres

E132

International Journal of Radiation Oncology  Biology  Physics

serial endoscopy and/or imaging studies. Overall survival (OS) and local control (LC) rates were calculated by the Kaplan-Meier method. Toxicities were evaluated by the Common Terminology Criteria for Adverse Events version 4.0. Results: For all 78 patients, the 3-year LC and OS rates were 62% and 26%, respectively; they were 100% and 100%, respectively, in Group 1, and 76% and 40%, respectively, in Group 2. The 2-year LC and OS were 63% and 15%, respectively, in Group 3, and 62% and 16%, respectively, in Group 4. Overall response rate was 76% (complete response in 28 and partial response in 31). Grade 3 or higher acute toxicities, mainly hematological, were observed in 45% of the patients and 10% experienced grade 3-4 late toxicities. Conclusion: CRT with standard FP and 60-70 Gy of radiation appears to be tolerable for patients with esophageal cancer. Although outcome of this treatment in inoperable patients is not satisfactory, the 3-year LC of 100% for stage I patients and 76% for stage II-III operable patients appear promising. Further investigation is warranted to clarify the optimal radiation dose in CRT for esophageal cancer. Author Disclosure: T. Kondo: None. Y. Shibamoto: None. A. Hayashi: None. T. Takaoka: None. T. Murai: None. A. Miyakawa: None. C. Sugie: None. T. Yanagi: None. M. Matsuo: None.

after accounting for tumor burden and CTP score. Our results suggest that HCC patients with left-sided lesions may benefit from a modified therapeutic approach. Author Disclosure: K.A. Plichta: None. S.K. Bhatia: None. M.W. Karwal: None. A. Reed: None. J. Buatti: None.

2334 Outcomes of Hepatocellular Carcinoma Treated With SBRT: Does Lesion Location Matter? K.A. Plichta, S.K. Bhatia, M.W. Karwal, A. Reed, and J. Buatti; University of Iowa Hospitals and Clinics, Iowa City, IA Purpose/Objective(s): We evaluated the impact of location of hepatocellular carcinoma (HCC) on overall survival (OS) in patients who received liver stereotactic body radiation therapy (SBRT). Materials/Methods: We identified 67 patients with HCC who received SBRT at our institution between 2003 and 2014. Inclusion criteria were a radiographic or pathologic diagnosis of HCC and a minimum of one year follow-up (or death prior to one year). Of the 67 total patients, 60 received trans-arterial chemoembolization (TACE) prior to SBRT, 7 received transplants after TACE+ SBRT, and 7 received SBRT as single modality treatment. Child-Turcotte-Pugh (CTP) and model for end-stage liver disease (MELD) scores were recorded. Cross-sectional imaging (MRI and/or CT scans) were reviewed for lesion location and size. Lesion location was classified as left (segments II, III, IV), right (segments V, VI, VII, VIII) or both/caudate. As a measure of overall tumor burden, maximum lesion diameter (which was additive in the case of multiple lesions) was recorded. Kaplan-Meier analyses with log rank tests were performed to evaluate OS. A predictive model was then built using Cox proportional hazards regression. Results: Of the 67 total patients, 46 were CTP A, 19 were CTP B, 1 was CTP C, and 1 had unknown CTP status. Overall survival was increased among CTP A patients in comparison to CTP B/C (median survival 32 .1 months vs 23.6 months, pZ0.002). A significant cut-off value was not identified for MELD scores. For tumor burden, a cutoff value was identified at 2.05cm using ROC analysis. Tumor burden <2.05cm resulted in significantly higher OS (69.2 months vs 23.6 months, pZ0.001). In terms of lesion location, 15 patients had left-sided lesions, 42 patients had right-sided lesions and 10 patients had lesions in both/ caudate. OS among the three groups was significant (median survival left: 17.7 months, right: 39.4 months, and both: 16.2 months, pZ0.001), and a significant difference in OS between patients with left versus right-sided lesions was found (p <0.0005). On multivariate analysis, CTP, tumor burden and lesion location remained significant (p-values 0.039 for CTP, 0.049 for tumor burden, and 0.011 for left versus right). Hazard ratios were 1.960 for CTP score (CI 1.035 to 3.709), 0.410 for left versus right lesion location (CI 0.205 to 0.818), and 2.282 for tumor burden (CI 1.004 to 5.186). Conclusion: HCC lesions located in the right side of the liver were associated with better overall survival in patients who received SBRT inclusive of patients who had subsequent transplant. This association persisted, even

2335 Stereotactic Body Radiation for Pancreatic Cancer: Results of an International Survey of Practice Patterns A. Parekh,1 L.M. Rosati,2 D.T. Chang,3 K.A. Goodman,4 A.C. Koong,5 and J.M. Herman6; 1Department of Radiation Oncology, Johns Hopkins Hospital, Baltimore, MD, 2Johns Hopkins University School of Medicine, Baltimore, MD, 3Stanford Cancer Institute, Stanford, CA, 4Memorial Sloan Kettering Cancer Center, New York, NY, 5Stanford University, Stanford, CA, 6Johns Hopkins Hospital, Baltimore, MD Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) is an emerging treatment option for locally advanced and unresectable pancreatic cancer (PCA), with early studies showing promising results. SBRT significantly decreases the duration of treatment allowing for more rapid initiation of systemic chemotherapy or surgical management. However, no standardized guidelines for treatment exist and patterns of SBRT use for PCA are unclear. Here we report the results of an international survey of practice patterns of SBRT for PCA among radiation oncologists. Materials/Methods: Thirty-four academic radiation oncologists from the United States, Europe and Canada known to use SBRT in the setting of PCA were invited to complete a 26-item Web-based survey on practice patterns. Questions focused on decision-making processes, treatment management, and radiation therapy practice environment. Data were analyzed anonymously. Results: Twenty-eight of the 34 (82.3%) invited radiation oncologists completed the survey. Of the responders, 85.7% treat with 6-8 Gy x 5 fractions and 14.3% with 10-15 Gy x 3 fractions. 85.2% of physicians also prefer SBRT over intensity-modulated (IMRT) or 3D conformal (3D CRT) radiation therapy. The majority (92.9%) of responders use four-dimensional computed tomography (4D-CT) for simulation, with 48% using gating to account for breathing motion. Two-thirds of radiation oncologists use fiducials for tumor localization. Improvement in pain after SBRT is observed among 81.5% of responders. Approximately 55.5% report difficulty obtaining insurance clearance for pancreas SBRT in the absence of a clinical trial. The majority (96.3%) report using Linac-based radiation for treatment. The most significant variations in practice were related to gross tumor volume (GTV) to planning target volume (PTV) expansions and management of respiratory motion. Conclusion: SBRT is increasingly used for PCA and has emerged as a viable treatment option for this disease. The data presented here indicate that the majority of radiation oncologists treat with 6-8 Gy x 5 fractions and use fiducials with 4D-CT simulation for localization and planning. Although the majority of treating physicians prefer SBRT to standard radiation, pancreas SBRT may be underutilized due to difficulty obtaining insurance approval off protocol. Our investigation documents current pancreas SBRT practice patterns and highlights the need for prospective clinical trials as a means to develop consensus guidelines for this emerging treatment. Author Disclosure: A. Parekh: None. L.M. Rosati: None. D.T. Chang: None. K.A. Goodman: None. A.C. Koong: None. J.M. Herman: Research Grant; Nucletron.

2336 Predictors of Survival in Yttrium-90 Radioembolization of Hepatic Malignancies With Resin Microspheres N.B. Newman,1 P.A. Ohman-Strickland,2 D. Carpizo,3 B. Benson,1 R.H. Gensure,1 C.A. Schonewolf,1 R.A. Moss,4 L. Melstrom,3 J.L. Nosher,5 and S.K. Jabbour6; 1Rutgers Cancer Institute of New Jersey Department of Radiation Oncology, New Brunswick, NJ, 2Rutgers School

Volume 93  Number 3S  Supplement 2015 of Public Health, New Brunswick, NJ, 3Rutgers Cancer Institute of New Jersey Division of Surgical Oncology, New Brunswick, NJ, 4Rutgers Cancer Institute of New Jersey Division of Medical Oncology, New Brunswick, NJ, 5Department of Radiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey, New Brunswick, NJ, 6 Rutgers Cancer Institute of New Jersey, New Brunswick, NJ Purpose/Objective(s): To identify which clinical parameters confer a survival benefit for patients with hepatic malignancies treated with Yttrium-90 Radioembolization (RE) resin-based microspheres. Materials/Methods: We prospectively collected data on 99 patients with unresectable hepatic malignancies treated with resin microspheres for Yittrium-90 radioembolization (RE) from 5/2007 to 12/2013. Patients were followed for survival from first RE treatment. Baseline laboratory values and imaging were done prior to the procedure. Prognostic factors evaluated included age, gender, chemotherapy agents, Eastern Cooperative Oncology Group Performance Status (ECOG PS), tumor histology, prior chemotherapeutic regimens, alanine aminotransferase (ALT), Aspartate aminotransferase (AST), bilirubin, Alkaline phosphatase (ALP), albumin, presence of extra-hepatic disease, tumor burden, lung shunting, number of lobes treated, dominant lesions, synchronous lesions, radiation dose, presence of diabetes, coronary artery disease, hypertension, and tumor marker levels. Survival from initial treatment with RE was estimated with Kaplan Meir curves. Univariate and multivariate Cox proportional hazard models were constructed to measure the effect of each prognostic factor. Results: Median overall survival from first RE treatment was 8.8 months (95% CI 7.6-10.8 months) for all patients and 13.2 months for those with colorectal metastases. On univariate analysis, higher albumin levels (pZ 0.0105), metachronous disease (pZ0.041), lower bilirubin levels (pZ0.024), lower AST (pZ0.018), presence of neuroendocrine malignancy (pZ0.004), and lack of extrahepatic lesions (pZ0.0031) correlated with improved overall survival. Multivariate analysis revealed improved survival with higher albumin (pZ0.0148) and lower bilirubin (pZ0.037) levels. Conclusion: Patients with lower bilirubin and higher albumin levels, markers of liver function and overall nutritional status, respectively, are likely to be candidates better suited for hepatic RE. Continued prospective trials will elucidate additional prognostic factors for improved survival and will aid clinicians to select optimal candidates for resin based 90Y RE. Author Disclosure: N.B. Newman: None. P.A. Ohman-Strickland: None. D. Carpizo: None. B. Benson: None. R.H. Gensure: None. C.A. Schonewolf: None. R.A. Moss: None. L. Melstrom: None. J.L. Nosher: None. S.K. Jabbour: None.

2337 A Retrospective Analysis of ITV Margins in 4DCT Planning for Patients With Esophageal Cancer Treated With Chemoradiation Y. Kobayashi,1 M. Myojin,2 M. Ishikawa,3 H. Takahashi,1 T. Shimazaki,1 and M. Hosokawa1; 1Keiyukai Sapporo, Sapporo, Japan, 2Keiyukai Sapporo Hospital, Sapporo, Japan, 3Department of Medical Physics, Hokkaido University Graduate School of Medicine, Sapporo, Japan Abstract Text: Purpose/Objective(s): In radiation treatment planning (RTP) using 4DCT under free breathing for esophageal cancer, there are few reports about difference of esophageal motion (EM) according to T stages and subsites of primary tumor, and motion of metastatic regional lymph nodes with pathological confirmation. We analyzed for two objectives as follows: (1) To evaluate the EM according to T stages and primary tumor subsites in the 4DCT planning; (2) To evaluate motion of metastatic lymph nodes pathologically defined by surgery following chemoradiation. Materials/Methods: Thirty-three patients with esophageal cancer were analyzed to measure 3-dimensional (LR, AP, SI) EM in 4DCT planning. Primary tumor subsites were: upper thoracic (Ut) 12, mid thoracic (Mt) 10, lower thoracic (Lt) 11. All esophageal contours were divided into the upper and the lower portion at the tracheal bifurcation. The 4DCT images (2.5 mm slice) were obtained using Real-Time Position Management Respiratory Gating System (RPM) system to sort 4D images into 10 phases. We

Poster Viewing Session E133 Poster Viewing Abstracts 2337; Table 1 EM of the lower portion (Mean  SD mm) Primary tumor subsites

T stage

N

Ut

T1-T3 T4 T1-T3 T4 T1-T3 T4

7 5 5 5 7 4

Mt Lt

LR 1.1 0.4 0.7 0.4 1.2 0.4

0.6 0.1 0.4 0.4 0.8 0.5

AP 1.8 1.2 1.6 0.8 2.1 0.4

1.7 0.8 0.8 0.5 1.0 0.2

SI 5.4 5.3 6.7 2.6 6.9 1.8

3.0 1.4 3.6 1.1 2.9 0.7

*Lower portion: below the tracheal bifurcation

selected two images (the end of inhale and exhale), and the centroid point was set to each upper and lower contours of the esophagus or each involved lymph node in those phases. We compared the difference of EM that was obtained by the centroid motion between two phases, according to T stages and primary tumor subsites. The traditional peak to peak method was discarded because of imaging uncertainty. We also analyzed 9 cervicothoracic and 5 abdominal lymph nodal motion (NM) in pathologically defined cases. We used t-test for each analysis. Results: In patients with T4 primary tumor, the distances of EM were statistically different according to subsites of primary tumor. These significant differences were between the primary site of Lt and Ut (AP: p Z 0.04, SI: p < 0.01) and between the primary site of Mt and Ut (SI: p < 0.01). In patients with primary Lt tumor, EM of the lower portion was significantly smaller in T4 cases than in T1-T3 cases (AP, SI: p < 0.01). In primary Mt tumor, similar result was obtained in one direction (SI: p Z 0.029). In patients with T1-T3 primary tumor, there was no significant difference of EM among any pair of primary subsites. The distances of EM of the upper portion were not dependent on T stages and primary tumor subsites. In comparison of EM and NM, abdominal NM was larger (LR Z 1.6 mm, AP Z 4.1 mm, SI Z 10.0 mm) than EM of the lower portion without exception. Conclusion: (1) We can use less ITV margins in RTP for T4 cases than those in T1-T3. (2) The ITV margins have to be determined individually, according to primary tumor location and presence of involved lymph node lower than the diaphragm. Author Disclosure: Y. Kobayashi: None. M. Myojin: None. M. Ishikawa: None. H. Takahashi: None. T. Shimazaki: None. M. Hosokawa: None.

2338 Intensity Modulated Radiation Therapy With S-1 Versus Capecitabine as Adjuvant Treatment for Locally Advanced Gastric Cancer X. Wang,1 Y. Tang,1 J. Jin,2 H. Ren,1 H. Fang,2 N. Li,3 X. Chen,1 T. Zhang,1 Y. Song,1 S.L. Wang,1 W. Wang,1 Y. Liu,2 and Y.X. Li2; 1 Cancer Hospital & Institute, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China, 2Cancer Hospital and Institute, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China, 3Cancer Hospital & Institute, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China Purpose/Objective(s): This study aimed to compare the safety of two oral fluoropyrimidines, S-1 or capecitabine, when combined with intensity modulated radiation therapy (IMRT) as an adjuvant treatment for locally advanced gastric cancer. Materials/Methods: Patient populations were combined from 2 prospectively conducted, phase II trial of S-1 or capecitabine based postoperative IMRT for locally advanced gastric cancer. We consecutively enrolled patients with pathologically stage as T3-4N0M0, or any T, N+M0 (AJCC 7th), gastroesophageal or gastric adenocarcinoma after complete resection with negative margins (R0). Patients received capecitabine (1600mg/m2/d during treatment days) or S-1 (80 mg/m2/d every weekday) concurrently with IMRT (45Gy, 1.8 Gy/fraction, 5 days/week). An experienced physicist designed the