ESTRO 36 Abstract Book

S572 ESTRO 36 2017 _______________________________________________________________________________________________

department, Saint-Petersburg, Russian Federation 6 Dr. Berezin Medical Center, Radiology department, Saint-Petersburg, Russian Federation 7 Russian Scientific Center Of Radiology And Surgical Technologies, Radiation Therapy department, Saint- Petersburg, Russian Federation Purpose or Objective Locoregional recurrence is a major cause of death in patients with squamous cell carcinoma of the head and neck (HNSCC). At the moment, there are no clear recommendations and standards regarding the timing, total doses and dose tolerance of normal tissues to re- exposure. Based on limited studies on the re-irradiation with high total doses, we evaluated the tolerability and clinical outcomes of high-dose chemo-reirradiation with simultaneous integrated boost. Material and Methods 18 patients with histologically confirmed locoregional recurrence of HNSCC, received chemo-reirradiation. Median time after primary radiotherapy course was 60 months. The treatment volumes and total doses were formed as follows: GTV (primary lesion and involved lymph nodes, delineated on CT, MRI and 18 F-FDG PET-CT) + CTV (0.5-1.0 cm) + PTV (0.3-0.5 cm) was treated to the total dose equivalent to 66-70 Gy of conventional fractionation, the high-risk lymph nodes (if indicated, PTV 0.5 cm) to 60 Gy, the low-risk lymph nodes (if indicated, PTV 0,5 cm) – equivalent to 50 Gy. Single doses to these volumes were 2.14-2.21 Gy, 2.0 Gy and 1.8 Gy, respectively. Radiation treatment was once a day, five days a week, 6 weeks long (30 fractions). Varian Eclipse v.10 was used for treatment planning (IMRT and VMAT); patients were treated on Varian Clinac 2100 and Varian TrueBeam STx. According to the literature, in a year after primary irradiation almost complete recovery of normal tissue tolerances is observed. Tolerances of organs at risk were not exceeded. IGRT was used for patient positioning. Patients received cisplatin every three weeks, 100 mg/m 2 . Results 16 of 18 patients received full course of radiation therapy without a break. Radiation toxicity manifested with grade 2-3 oral and pharyngeal mucositis and grade 2 radiation epidermitis. After one month, almost complete relief of radiation mucositis and dermatitis was observed. One patient took a break of 7 days after 25th fraction due to the development of grade 3 mucositis and grade 3 dysphagia. Late toxicity were grade 2 xerostomia in 1 patient (recurrent tumor, located near the parotid salivary glands), chronic atrophic sinusitis - in 2 patients (recurrence in the ethmoidal labyrinth and maxillary sinus). In 14 patients, who received re-irradiation with a total dose of more than 60 Gy, partial response was observed at the first follow-up examination (MRI) at 1 month after treatment. Two patients showed stabilization. Median follow-up was 11 months (from 2 to 20). One year overall survival was 48%. The cause of death in two patients was disease progression (distant metastases), two patients died from complications related to the treatment (elderly patients, who developed grade 3 dysphagia and subsequent septic complications). Conclusion Using technique of SIB with IMRT/VMAT during curative chemo-reirradiation of recurrent HNSCC is available with maintaining satisfactory tolerability. Local control rate is quite encouraging, and late toxicity is at acceptable rates. EP-1044 survival and functional outcome after treatment for primary base of tongue cancer S. Park 1 , Y. Cho 1 , J. Lee 1 , K.C. Keum 1 , C.G. Lee 1 1 Yonsei university college of medicine, Radiation oncology, Seoul, Korea Republic of

The preservation of speech and swallowing function in the treatment of base of tongue (BOT) cancer is critical issue. At present, BOT cancer patients treated with either surgery followed by postoperative radiotherapy or definitive RT without consensus of optimal treatment. The purpose of this study is to compare the clinical and functional outcome in patients with primary BOT cancer who received definitive radiotherapy or surgery followed by radiotherapy. Material and Methods Between January 2002 and June 2016, a total number of 99 patients with stage I-IVB primary BOT squamous cell carcinoma underwent either definitive radiotherapy (RT group, n=43) or surgery followed by radiotherapy (SRT group, n=56). In the RT group, 28 patients (65.1%) were treated with concurrent chemotherapy and 11 patients (25.6%) with induction plus concurrent chemotherapy. In the SRT group, 18 patients (32.1%) received concurrent chemotherapy. Median radiation doses of the RT group and SRT group were 70 Gy (range, 63-76 Gy) and 63 Gy (range, 45-68.4 Gy), respectively. Radiotherapy was performed using both 3-demensional conformal RT (3D CRT, n=30) and Intensity modulated RT (IMRT, n=69). Among patients in SRT group, 31 patients (55.4%) were treated with wide excision, 18 (32.1%) with partial glossectomy, and 7 (12.5%) with total glossectomy. Expression of p16 was available in 53 patients (53.5%). Among these, 38 patients (71.7%) had p16 positive and 15 patients (28.3%) had p16 negative BOT cancer. Results The median age of patients was 59 years (range, 36-96). There were more patients that had advanced T stage (T3- 4) disease (58.1% vs. 37.5%, p=0.041) and received chemotherapy (90.6% vs. 35.7%, p=0.001) in RT group than those in SRT group. At a median follow up of 36.1 months (range, 0.8-178.4), 5-year overall survival (OS) and disease free survival (DFS) were 74.6% and 69.6%, respectively. Respect to treatment group, 5-year OS and DFS in both RT group and SRT group were 71% vs. 77.2% (p=0.941) and 65% vs. 72.9% (p=0.805), respectively. In univariate analysis, T stage (OS: p=0.041, DFS: p=0.008), RT modality (OS: p=0.004, DFS: p=0.002) and p16 expression (OS: p=0.009, DFS: p=0.009) were observed prognostic factors related to both OS and DFS. In multivariate analysis, OS showed significant difference according to p16 expression (p16 negative vs. p16 positive, HR 0.152, 95% CI 0.028-0.816, p=0.028). Regarding DFS, p16 expression (p16 negative vs. p16 positive, HR 0.261, 95% CI 0.073-0.936, p=0.039) showed significant effect in multivariate analysis. Dysphagia and voice alteration (severe than grade 2) were more frequently observed in SRT group than RT group (19.6% vs. 2.3%, p=0.009). Conclusion Even with more advanced disease, patients in RT group showed comparable survival outcome with better functional preservation to those in SRT group. EP-1045 L Glutamine in reducing severity of oral mucositis due to chemoradiation in head and neck cancer V. Pareek 1 , R. Bhalavat 2 , M. Chandra 2 1 Jupiter Hospital- Thane, Radiation Oncology, Mumbai, India 2 Jupiter Hospital, Radiation Oncology, Thane, India Purpose or Objective The incidence of mucositis in the oral cavity, pharynx and larynx is high among patients with head and neck cancer (HNC) receiving chemo-radiotherapy (CRT), resulting in significant pain and impairment of quality of life. The present study investigated whether L-glutamine (glutamine) decreases the severity of mucositis in the oral cavity, pharynx and larynx induced by CRT Material and Methods

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