ESTRO 37 Abstract book

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ESTRO 37

L. Pettit 1 , A.G. Welsh 1 , M.T. Williams 1 , C.H. Puzey 1 1 Shrewsbury and Telford Hospital NHS Trust, Lingen Davies Cancer Center- Royal Shrewsbury Hospital, Shrewsbury, United Kingdom Purpose or Objective Parotid sparing IMRT has been shown to reduce incidence of xerostomia, leading to recovery of salivary function and subsequently improve quality of life. It is usual to contour the whole parotid gland (WPG) which is considered a parallel organ. It can be challenging to meet dose constraints of the WPG even with VMAT. The general consensus in the U.K. has been to use a simple planning constraint of mean < 24 Gy to the WPG. However, this is not always achievable, especially with large tumours. Previous work suggests if only part of the parotid was spared this may be enough for preservation of saliva function. Material and Methods A retrospective dosimetric analysis of ten previous unselected patients who had received bilateral radical radiotherapy 65 Gy in 30 fractions for squamous cell carcinoma of the oropharynx that were identified from ARIA. Demographics were recorded on an excel spreadsheet. The deep lobe (DL) and superficial lobe (SL) of the ipsilateral (IL) and contralateral (CL) parotid gland were contoured on each CT planning slice. Mean dose to the deep lobe (DL) and superficial lobe (SL) was calculated from the original plan with the volume of the WPG. V40 and D50 were recorded. All treatment was re- planned using a SL tolerance of V40 < 33% and D50 < 50% without compromise to the PTV’s or change to other OAR. The DL of the parotid was not considered an organ at risk (OAR) for the re-plan. Results 10 patients were identified. 8 male, 2 female. All had squamous cell carcinoma of the oropharynx, 7 had tonsilar primaries, 2 base of tongue and 1 posterior pharyngeal wall. 7 were positive for p16. 9 also received concurrent platinum based chemotherapy.

out using a modified clinical activity score (CAS). Follow- up was closed in February 2017. Results A total of 49 orbits were treated. All patients completed the planned treatment with no acute G2-3 toxicities registered. Evaluation of patients was performed by the CAS parameters before and 6 months after treatment. At a median follow up time of 11.24 months, we have not observed any late toxicity from this regimen. CAS pre- treatment evaluation was: Mean 4.31±1.27 (range: 2-7), median: 4.0. CAS post-treatment: Mean 1.47±1.8 (range: 0-6), median 1.0 (p<0.0001). All patients with pre- treatment CAS below 4 remain free of active disesase after treatment. On the other hand, 26 out of the 34 (76.5%) pre-treatment active disease showed a response changing to non active disease (p=0.04). Conclusion The significant improvement seen after treatment in most clinical parameters assessed seems to justify this regimen of treatment as an effective and well tolerated therapeutic option for patients with Graves’ Ophthalmopathy. EP-1106 Role of hyperfractionated radiotherapy with chemoimmunotherapy in advanced head and neck carcinoma R. Carmona-Vigo 1 , J.M. Blanco Suárez 1 , M. Lloret Sáez- Bravo 1 , R. Cabrera Díaz-Saavedra 1 , P.C. Lara Jiménez 1 1 Las Palmas de Gran Canaria, Radiation Oncology, Las Palmas de Gran Canaria, Spain Purpose or Objective The aim of the present study is to analyze clinical outcomes and toxicity in patients with advanced head and neck carcinoma treated with concurrent hyperfractionated radiotherapy with Cetuximab and Carboplatin. Material and Methods Forty-one patients (8 cases ST.III and 33 cases ST.IV) were prospectively included in this study from September 2009 to November 2014. Radiotherapy consisted in hyperfractionated radiotherapy: 1.15-1.20 Gy/fraction, BID, 5 days/week during 7 weeks. The average dose administered was 80.2 Gy (79.2-80.5). Carboplatin was administered 5 mg/m2 before each fraction of radiotherapy. Cetuximab was administered 400 mg/m2 one week before hyperfractionated radiotherapy and then 250 mg/m2 weekly while radiotherapy. Seven patients were not evaluable for response (in 3 patients, Capecitabine was added to the treatment; in 1 patient nodal metastases came from a papillary thyroid carcinoma; 3 patients were not evaluable for response because 2 patients died within 30 days after treatment and 1 patient has not enough follow-up to be evaluated for response). Results All but 2 of the 34 evaluable patients showed objective response (19 complete responses). The local relapse-free survival, cause specific survival, and overall survival was 58.7%, 57%, 49% at 5 years, respectively. Severe (Grado II/III) acneiform rash resulted predictive of clinical response (p=0,005), local relapse (p=0,008), distant metastases (p=0,012) and tumour related dead free survival (p<0,0001). Severe (Grade III) acute cutaneous and mucosal toxicity was present in almost 60% of the cases. Conclusion This protocol induces a high rate of clinical responses and excellent survival figures in patients developing a strong immune response after combined radio-chemoimmuno- therapy. EP-1107 Sparing the superficial lobe of the parotid during radical radiotherapy for oropharyngeal carcinoma

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As expected the mean volume of the IL and CL parotid were similar (32.8 cc IL (7.8 cc DL, 24.7 cc SL, 31.9 cc CL (7.6 cc DL, 23.7 cc SL). On average, the DL accounted for 24.8% of the IL parotid and 25.1% of the CL parotid. Average IL SL mean dose was significantly reduced from 36.1 Gy to 33.9 Gy, average CL SL mean dose reduced from 28.3 Gy to 25.5 Gy (p = 0.02 t-test). Conclusion Our retrospective study confirmed that tolerances to the superficial lobe only are relatively easy and practical to meet. Previous work suggests that D50 may be a more reliable predictor of recovery of parotid function than mean dose to whole gland. Following this retrospective study our department will change dose constraints to superficial lobe V40 < 33% and D50 < 50% and no longer consider the deep lobe an OAR. Prospective data will investigate preservation of salivary function using D50/V40. EP-1108 MMF Reduces Acute Radiation Dermatitis in Head and Neck Squamous Cell Carcinomas 'patients