ESTRO 37 Abstract book

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ESTRO 37

hydroxyurea according to the previously reported Vokes protocol (VP arm), or 60 Gy and 1.2 Gy per fraction twice daily combined with cetuximab (Hyper-Fractionated Radiotherapy: HFR arm). Eligibility criteria were: recurrence or a second primary in a previously irradiated area, no major sequelae due to the first radiotherapy, no distant metastasis, salvage surgery with macroscopic complete resection. Results twenty six patients were included in VP arm and 27 in HFR arm. There was no imbalance in the distribution of the main tumor and patients characteristics. Only one patient in VP arm experienced more than 15 days of treatment interruption due to toxicity, and none in HFR arm (primary endpoint). In both arms, all patients received at least 60 Gy. In VP arm 8/ 26 patients had delay and/or dose reduction of chemotherapy. In HFR arm, 4/27 patients had less than 6 cycles of cetuximab. There was an improved overall survival in HFR arm than in VP arm, however the difference was not significant between the 2 arms (Median OS 37.4 months [95% CI: 16.1 - NA] vs 21.9 months [95% CI: 12.9 - 33], p = 0.12). Acute and late toxicities and disease-free survival were not statistically different between the 2 arms. Conclusion the twice daily schedule of re-irradiation of 60Gy/ 5 weeks with concomitant weekly cetuximab is well tolerated and can be proposed after salvage surgery of recurrent HNSCC. However the twice daily schedule can be difficult to organize. It was the main raison for the slow accrual of patients in this trial. OC-0273 Phase II Trial of De-intensified Chemoradiotherapy for HPV-associated Oropharyngeal Cancer B. Chera 1 , R. Amdur 2 , X. Tan 3 , N. Hayes 4 , J. Weiss 5 , J. Grilley-Olson 5 , A. Zanation 6 , T. Hackman 6 , J. Zevallos 7 , S. Patel 6 , N. Sheets 8 , M. Weissler 6 , W. Mendenhall 2 1 The University of North Carolina, Radiation Oncology, Chapel Hill NC, USA 2 University of Florida, Radiation Oncology, Gainesville, USA 3 University of North Carolina, Lineberger Comprehensive Cancer Center, Chapel Hill, USA 4 University of Tennessee Health Science Center, Hematology/Oncology, Memphis, USA 5 University of North Carolina, Hematology/Oncology, Chapel Hill, USA 6 University of North Carolina, Otolaryngology, Chapel Hill, USA 7 Washington University, Otolaryngology, St Louis, USA Purpose or Objective To report initial results from a prospective phase II clinical trial of highly de-intensified chemoradiotherapy (CRT) for patients with favorable risk HPV-associated oropharyngeal squamous cell carcinoma (OPSCC). Material and Methods The major inclusion criteria were: 1) T0-T3, N0-N2c, M0, 2) HPV or p16 positive, and 3) minimal/remote smoking history. Treatment was limited to 60 Gy intensity modulated radiotherapy with concurrent weekly intravenous cisplatin 30 mg/m 2 (second choice was cetuximab). Patients received neither induction chemotherapy nor definitive surgery. Patients with T0-T2 N0-1 disease did not receive chemotherapy (i.e. received 60 Gy alone). All patients had a 10 to 12-week post- treatment PET/CT to determine need for planned neck dissection. The primary study endpoint is 2 year progression free survival (PFS). Secondary endpoint measures include 2 year local control (LC), regional control (RC), distant metastasis free survival (DMFS), and overall survival (OS), and patient reported symptoms 8 Rex/UNC Healthcare, Radiation Oncology, Raleigh, USA

(PRO-CTCAE) and quality of life (EORTC QLQ-C30 & H&N35). Data analysis was peformed for patients with a minimum of 1 year of follow-up. Results 113 patients have enrolled with 82 having a minimum follow-up of 1 year. Smoking status was as follows: 49% never, 35% ≤ 10 pack years, and 16% > 10 pack years. Forty-four percent were HPV and p16 positive and 56% were HPV negative/unknown and p16 positive. Post- treatment PET/CT complete response rate was 97% at the primary site and 81% in the neck. Eight patients had planned neck dissection with 1 having pathological residual disease. Two year PFS, LC, RC, DMFS, CSS, and OS were the following: 93%, 98%, 99%, 95%, 96%, and 95%. 16 patients were treated with RT alone and all remain in cancer control. Mean pre- and 1-year post-treatment EORTC QOL scores were: Global 79/82 (lower worse), Swallowing 8/12 (higher worse), Dry Mouth 15/55 (higher worse), and Sticky Saliva 10/33 (higher worse). 39% of patients required a feeding tube (none permanent) for a median of 10.5 weeks (range 3-42 weeks). Mean pre- and 1 year post-treatment PRO-CTCAE (0 to 4 scale, higher worse) scores were: Swallowing 0.5/0.9 and Dry mouth 0.5/1.6. There were no ≥ Grade 3 late adverse events. Conclusion Initial clinical outcomes with highly de-intensified CRT are excellent in favorable risk OPSCC with evidence of better preservation of quality of life as compared to standard therapies (ClinicalTrials.gov, NCT02281955). OC-0274 Effect of radiotherapy technique/fractionation on 2-year primary local control in the PET-NECK study C.T.K. Fong 1 , C. McConkey 2 , P. Sanghera 1 , A. Hartley 1 , J.K. Rahman 2 , C. Nutting 3 , H. Al-Booz 4 , M. Robinson 5 , H. Mehanna 6 1 Queen Elizabeth Hospital Birmingham, Hall-Edwards Radiotherapy Research Group, Birmingham, United Kingdom 2 University of Warwick, Clinical Trials Unit, Warwick, United Kingdom 3 Royal Marsden Hospital, Cancer Institute, London, United Kingdom 4 Bristol Haematology and Oncology Centre, Oncology, Bristol, United Kingdom 5 Weston Park Hospital, Oncology, Sheffield, United Kingdom 6 University of Birmingham, Institute of Head and Neck Studies and Education, Birmingham, United Kingdom Purpose or Objective The randomised phase 3 PET-NECK study demonstrated that PET-CT scan surveillance resulted in similar survival but was more cost-effective than planned neck dissection for squamous cell carcinoma of the head and neck (SCCHN) with N2 or N3 stage. In addition, the similar outcomes in overall survival and global quality of life seen in the study between the permitted radiotherapy techniques [intensity modulated radiotherapy (IMRT) vs 3D conformal radiotherapy (3D-CRT)] and between the permitted fractionations [7 week (68-70Gy/34-35# over 45-46 days) vs 6 week (60-66Gy/30# over 39 days) vs 4 week (55Gy/20# over 25 days)] has already been presented. The predominance of hypofractionated accelerated regimes and the use of synchronous chemotherapy in all patients makes the primary local control data from this study of particular radiobiological interest for ongoing and future randomised studies. Material and Methods In the 532 (94%) patients where data on technique was available: 200 (38%) received 3D-CRT and 332 (62%) received IMRT. In the 525 patients where fractionation data was available: 181 (34%), 288 (55%), and 56 (11%) patients received 68-70 Gy in 34-35 fractions (#), 60-66 Gy in 30#, and 55Gy in 20# respectively. Baseline

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