Outcome Predictors for Major Salivary Gland Carcinoma Following Postoperative Radiation Therapy

E310

International Journal of Radiation Oncology  Biology  Physics

of tumor location, tumor stage, CTV volume, and treatment modality (Table 1). Conclusion: Treatment plan robustness may be an important factor for local failure in VMAT. Accuracy of delineation of target volumes and adequacy of planning target volume margins needs to be further evaluated. Author Disclosure: W. Liu: None. S.H. Patel: None. D. Harrington: None. J. Stoker: None. X. Ding: None. J. Shen: None. W.W. Wong: None. M. Halyard: None. S.E. Schild: None. G.A. Ezzell: None. M. Bues: None.

Author Disclosure: A. Hosni: None. S. Huang: None. D. Goldstein: None. W. Xu: None. B. Chan: None. A. Hansen: None. A. Bayley: None. S. Bratman: None. J. Cho: None. M.E. Giuliani: Travel Expenses; ELEKTA Inc. A.J. Hope: Consultant; ELEKTA Inc. J.J. Kim: None. B. O’Sullivan: None. J. Waldron: None. J.G. Ringash: None.

2769 Outcome Predictors for Major Salivary Gland Carcinoma Following Postoperative Radiation Therapy A. Hosni,1 S.H. Huang,1 D. Goldstein,1 W. Xu,1 B. Chan,1 A. Hansen,1 A. Bayley,1 S. Bratman,1 J. Cho,1 M.E. Giuliani,1 A.J. Hope,1 J.J. Kim,2 B. O’Sullivan,1 J. Waldron,1 and J.G. Ringash1; 1Princess Margaret Cancer Centre / University of Toronto, Toronto, ON, Canada, 2Princess Margaret Cancer Centre, Toronto, ON, Canada Purpose/Objective(s): To report the outcome of postoperative radiation therapy (PORT) for salivary gland carcinoma (SGC) and identify patients at high risk of distant metastases (DM) who might benefit from systemic therapy. Materials/Methods: Patients with major SGC treated between 2000 and 2012 were reviewed retrospectively. All patients underwent initial primary maximal resection with preservation of major nerves unless encased by tumor. Neck dissection (ND) was performed therapeutically in N+ or electively (N0, if high grade and/or T3/4). PORT was delivered using 3-dimensional conformal radiation therapy (3DCRT) or intensity modified RT (IMRT) for risk features: T3/4, N+, positive/ close margin, high risk pathology, nerve involvement. Local (LC), regional (RC), distant control (DC); and cause-specific survival (CSS) were analyzed with competing risk method. Overall survival (OS) was calculated with Kaplan-Meier method. Multivariate analysis (MVA) using Cox proportional hazards model assessed predictors for DM, CSS, and OS. Results: A total of 304 patients were identified: 48% were stage III/IV and 22% had lymphovascular invasion (LVI). The most common primary site was parotid gland (nZ237; 78%). High-risk pathology was found in 190 patients (62.5%) as follows: salivary duct carcinoma (nZ40), SCC (nZ11), G2/3 adenocarcinoma (nZ15), G2/3 mucoepidermoid (nZ35), G2/3 carcinoma ex-pleomorphic adenoma (nZ22), G3 adenoid cystic carcinoma (nZ55) and rare histologies (nZ12). Margin status was: involved (nZ152, 50%), very close 1 mm (nZ98, 32%), close <5 mm (nZ22, 7%) and clear 5 mm (nZ32, 11%). ND was performed in 154 patients (51%), with nodal extracapsular extension (ECE) in 32. Adjuvant chemotherapy was used in 10 patients (3%), all of them with positive/very close margin and/or nodal ECE. IMRT (median dose 66 Gy) was used in 171 patients (56%) and 3D-CRT in 133 (44%; median dose 60 Gy). The 5-year and 10-year LC, RC, DC, CSS, OS were 96% (96%), 95% (94%), 80% (77%), 83% (82%), 78% (75%); respectively. Of 13 patients with local failure, 11 (85%) had positive margin (PZ.02). Regional failure occurred in 16 patients, 4 treated with IMRT and 12 with 3D-CRT (PZ.02). DM was the most frequent treatment failure (nZ 62), mainly in lung (nZ38). On MVA, stage III/IV, positive margin, and highrisk pathology significantly correlated with DM. Of 62 deaths, 49 were cancer related. MVA identified stage III/IV and LVI as poor predictors for CSS and OS, while positive margin predicted CSS only. No grade 4 or 5 RTOG late toxicity was reported; 10 patients had grade 3, including neck fibrosis (nZ4), osteoradionecrosis (nZ4), trismus (nZ1) and dysphagia (nZ1). Conclusion: Surgery and PORT achieved excellent long term outcomes and low rates of toxicity in SGC. Further research is required for patients with stage III/IV, positive margin, and high risk pathology to determine incremental benefit of concurrent chemotherapy with PORT to reduce DM.

2770 Follow-up Serum Lactic Dehydrogenase as a Predictor of Distant Metastasis and Survival for Patients With Nasopharyngeal Carcinoma J. Wang,1,2 Y.Y. Chen,1,2 L. Li,3 X. Chen,1,2 and M. Chen1,2; 1Zhejiang Cancer Hospital, Hangzhou, China, 2Zhejiang Key Laboratory of Radiation Oncology, Hangzhou, China, 3Ultrasonographic section, Zhejiang Cancer Hospital, Hangzhou, China Purpose/Objective(s): Pretreatment serum lactic dehydrogenase (LDH) was predictive of survival or distant metastasis among patients with nonmetastatic nasopharyngeal carcinoma (NPC). However, the predictive value of serum LDH after treatment was unknown. Hence, the purpose of this study was to examine the relationships between follow-up serum LDH and locoregional control, distant metastasis-free survival (DMFS), and overall survival among patients with nonmetastatic NPC after intensity modulated radiation therapy (IMRT). Materials/Methods: The charts of 739 nonmetastatic NPC patients admitted to 1 institution between January 2007 and May 2012 were reviewed. The patients were with normal renal, cardiac, and liver function. The median follow-up time is 34 Months. The relationships between follow-up serum LDH and locoregional control, distant metastasis-free survival (DMFS), and overall survival were identified. Results: For all patients, the cumulative survive rate of 1, 3, and 5 years was 97%, 92%, and 81%, respectively. The local and regional relapse-free survival rate of 1, 3, and 5 years was 99%, 93%, and 92%, respectively. The distant metastasis-free survival rate of 1, 3, and 5 years was 97%, 88%, and 82%, respectively. Distant metastasis rate was 32.8% (20/61) for patients with high LDH level during follow-up, 8% (54/678) for those with normal LDH level (OR 5.67, 95% CI 3.09-10.30, P<.001). The median DMFS was 46 months in patients with higher LDH level during follow-up versus 66 months among those with normal LDH level (HR 4.07, 95% CI 2.43-6.80, P<.001). The median DFS was 46 months among patients with higher LDH level during follow-up, 63 months among those with normal LDH level (HR 2.78, 95% CI 1.70-4.53, P<.001). The median OS was 54 months among patients with higher LDH level during follow-up, compared with 66 months among those with normal LDH level (HR 2.93, 95% CI 1.65-5.23, P<.001). COX regression showed that age (HR 1.05 95% CI 1.02-1.07, P<.001), radiation time (HR 1.05 95% CI 1.01-1.10, PZ.012), and LDH level during follow-up (HR 2.91 95% CI 1.57-5.41) were independent prognostic factors of worst outcome for nonmetastatic NPC patients. Conclusion: Our findings indicated that high serum LDH during follow-up provides easily available prognostic value for distant metastasis and survival for nonmetastatic NPC patients. Author Disclosure: J. Wang: None. Y. Chen: None. L. Li: None. X. Chen: None. M. Chen: None.

2771 A Comparison of Plan Quality and Delivery Efficiency Between Helical Tomotherapy in Fixed and Dynamic Delivery Mode in the Treatment of Nasopharyngeal Carcinoma W.W. Lam, H. Geng, C.W. Kong, Y.W. Ho, W.K.R. Wong, B. Yang, K.Y. Cheung, and S.K. Yu; Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong Purpose/Objective(s): The purpose of the study was to evaluate the plan quality and delivery efficiency between helical tomotherapy (HT) in dynamic jaw delivery mode with preset field width (FW) of 5 cm and that