ESTRO 37 Abstract book

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ESTRO 37

Conclusion So far, a correlation between an increase in dose to the cochlea and hearing deterioration could only be demonstrated in patients treated with RS. In the FSRT group, the results indicate that patients treated with a higher dose to the cochlea did not suffer more often from hearing deterioration, but quite in contrast the patients whose hearing deteriorated, received less dose to the cochlea, did show worsened symptoms. However, a satisfying conclusion can yet not be drawn since the patient groups are still small. Further, the cochlea is a very small structure and, therefore, hard to contour on 3- 4 CT slides. A large patient group will be needed to gather more sustainable results. Further sub-analyses are planned, as well as additional contouring and dosimetric analyses of the equilibrium organ and the correlation with the documented side effects of dizziness, imbalance and gait uncertainty. EP-1131 Treatment results of primary parotid carcinoma treated with surgery and postoperative radiotherapy Y.H. Kim 1 , W.K. Chung 1 , J.U. Jeong 1 , M.S. Yoon 1 , J.Y. Song 1 , T.K. Nam 1 , S.J. Ahn 1 , D.H. Lee 2 , T.M. Yoon 2 , J.K. Lee 2 , S.C. Lim 2 1 Chonnam National University Medical School, Radiation Oncology, Hwasun, Korea Republic of 2 Chonnam National University Medical School, Otorhinolaryngology-Head and Neck Surgery, Hwasun, Korea Republic of Purpose or Objective To investigate the treatment outcomes and prognostic factors of primary parotid carcinoma treated with surgery and postoperative radiotherapy (PORT). Material and Methods We reviewed 58 patients (M/F; 42/16, median age; 57 years) of primary parotid carcinoma who were treated with surgery and PORT between 2005 and 2014, retrospectively. Superficial parotidectomy was performed at 19 (32.8%) patients and total parotidectomy at 11 (19.0%), and total parotidectomy with lymph node dissection at 28 (48.2%) patients, respectively. Forty two (72.4%) patients received PORT at parotid bed, while 16 (27.6%) received at parotid bed and ipsilateral cervical lymph node bearing areas. The median dose of radiation was 50.4 Gy (range, 41.4–66.6 Gy). Results

(58.6%) and pT3-4 (pT3=11, pT4=13) were in 24 patients (41.4%). Cervical lymph node metastases were shown in 18 patients (31.0%). Forty patients (69.0%) had grade 1 (n=31) or 2 (n=9) tumor and 18 (31.0%) had grade 3. Five patients had recurrences at the primary lesion and 3 in the cervical nodes. Distant recurrences were reported in 9 patients, and simultaneous loco–regional and distant recurrences were reported in 4 patients. Most common site of distant metastasis was lung. Five patients (8.6%) of late toxicity more than grade 3 were observed in 5 years. On multivariate analysis, pathologic T stage (1–2 vs. 3–4) was the significant independent factor related to OS (89.3% vs. 56.3%, HR 4.79, p=0.007), DFS (80.5% vs. 33.9%, HR 4.49, p=0.002), and LRC (93.7% vs. 49.3%, HR 10.84, p=0.002) on 5–years. Tumor grade (1–2 vs. 3) affected 5–years DFS (76.3% vs. 25.3%, HR 3.46, p=0.006). Conclusion This study revealed that pathologic T stage and tumor grade were significant independent prognostic factors on clinical outcomes, and that is consistent with the previous reports on the literature. EP-1132 Toxicity analysis of pure modestly accelerated radiotherapy in post-operative oral cavity carcinomas S. Rath 1 , R. Khurana 1 , M. Rastogi 1 , K. Sahni 1 , R. Hadi 1 , S. Sapru 1 , A.K. Gandhi 1 , S.P. Mishra 1 , A.K. Srivastava 1 , S. Farzana 1 1 Dr Ram Manohar Lohia institute of Medical Sciences, Radiation Oncology, Lucknow, India Purpose or Objective Large randomised trials have shown improved local control and disease free survival by modest acceleration using six fractions per week radiotherapy (RT) in head and neck squamous cell carcinoma patients. We aimed to evaluate the role of pure modest accelerated fractionated radiotherapy (PM-AFRT) using 6 fraction per- week in patients of post-operative oral cavity squamous cell carcinomas (OCSCC). Material and Methods Between May 2015 to July 2016, post-operative OCSCC patients with one or more risk factors for RT [pathological tumour size (T3/T4), node positivity pN+, perineural invasion, lympho-vascular invasion and close margin (<5 mm)] were prospectively treated with adjuvant PM-AFRT. RT dose was 60 Gy in 30 fractions over 5 weeks, delivered by 3-D conformal technique on linear accelerator. Acceleration consisted of a sixth 2 Gy fraction on Saturday. Primary end point was to assess feasibility and toxicity. Patients were reviewed weekly during RT and monthly thereafter, using Radiation Therapy Oncology Group (RTOG) criteria. Analysis of acute and late toxicity is presented. Survival analysis was done by Kaplan-Meier method and all events were calculated from the date of registration. Results Forty patients were accrued. Patient characteristics are mentioned in figure 1. The median surgery-RT start time was 6.6 weeks (range 4.1-14.4). Grade 3 mucositis, pharynx/esophageal toxicity and skin toxicity were seen in 77.5%, 25% and 17.5% respectively. Two patients had grade 4 mucositis. Progression of acute toxicities over time is presented in figure 2. No other grade 4 toxicity was seen. 23 patients received intra-venous fluid support and 57.5% were on Ryle’s tube support during RT. All the patients were taken off Ryle’s tube within 4 weeks of RT completion. Median RT completion time was 36 days (range 33-41). 97.5% completed RT doses as planned. Three patients had treatment interruptions. The median weight loss was 5.8% (range 1-9). At last follow-up, grade 3 subcutaneous toxicity and xerostomia were documented in 5% and 2.5% respectively. The median follow-up was 21.2 months (range 5.4–29). The 2-year loco-regional control rate was 87%. There were two distant failures.

With median follow–up of 66 months (range, 8–124 months), the 5–year overall survival (OS), disease–free survival (DFS), and loco–regional control (LRC) rate were 75.2%, 61.0%, and 76.4%, respectively. Pathologic stage T1-2(pT1=12, pT2=22) were revealed in 34 patients