ESTRO 2020 Abstract book

S404 ESTRO 2020

of age and performance status implicate a high non- cancer-specific mortality in this cohort, which needs to be taken into account for therapy planning and further study designs. Concomitant chemotherapy should be critically discussed in elderly patients. PD-0665 Outcomes of head & neck paragangliomas treated with surgery, radiation therapy or close observation. A. Mangaj 1 , S. Ghosh-Laskar 1 , P. Pai 2 , A. Budrukkar 1 , D. Nair 2 , M. Swain 1 , N. Mummudi 1 , S. Thiagranjan 2 , N. Tiwari 2 1 Tata Memorial Centre, Radiation Oncology, Mumbai, India ; 2 Tata Memorial Centre, Surgical Oncology, Mumbai, India Purpose or Objective Head and Neck paragangliomas are rare, benign neuroendocrine tumors. Options for local management can include surgical resection or radiation therapy (RT) or close observation, however no consensus exists. We present our experience of patients with head and neck paragangliomas treated with surgery, radiation therapy or observation. Material and Methods We retrospectively analyzed 58 patients evaluated from July 2010 to April 2019 in our institution. All patients were evaluated in multi-disciplinary clinic with baseline MRI or HRCT of the local site and optimal management was decided. Twenty-four (41.4%) patients received radiation therapy, 9 (15.5%) underwent surgical resection, 24 (41.4%) patients were observed with serial MRI and 1 (1.7%) patient was planned for surgery followed by adjuvant radiation therapy.Radiation therapy was planned in patients who had extensive and unresectable disease 10/24 (41.6%) or in whom surgery would cause cranial nerve palsy 8/24 (33.3%) while 6/24 (25%) patient opted non-invasive modality of RT. Close observation was planned in patients who were asymptomatic and had small volume disease. The most frequently used regimen was 50Gy/25# in 18/24 (75%) patients, 45Gy/25# in 2 (3.4%), 54Gy/30# and 66Gy/33# in 2 patients each. All patients were planned IMRT with IGRT. Results The median follow-up was 41 months (IQR 13-64 months).The median age was 52 years (range 19-76 years). Twenty four (41.4%) were males and 34 (58.6%) were females. Ear discharge/bleeding was presenting complaint in 25 (43.1%) followed by neck swelling in 22 (37.9%) patients. Three (5.2%) patients had bilateral presentation. The diagnosis was Glomus jugulaire (GJ) in 34(58.6%), Glomus tympanicum (GT) in 12 (20.7%), Glomus vagale (GV) in 4 (6.9%) and Carotid body tumor (CBT) in 8 (13.8%) patients. In GT and GJ, 5 were Fisch class A, 7 were class B, 22 were class C and 5 were class D. Twenty eight (48.3%) presented with cranial nerve (CN) deficits with CN VII being most commonly involved followed by CN XII, X and VIII. The mean tumor size was 4.72 cm (range 1.41-10.2 cm) for the entire group, 4.5 cm (range 2.3-10.2 cm) in radiation therapy group, 2.1 cm (range 1.2-7 cm) in surgery group and 3.7 cm (range 1.9-5.6 cm) in observation group. The mean GTV volume was mean 98.5 cc (range 11.4–460 cc). The local control rates at 3 years were 81.9% for the entire group, while it was 94.4% in radiation therapy, 77.8% in surgery group and 79.4% in observation group. Post RT symptoms improved in 15/24 (62.5%) patients. No patient developed CN palsy post RT, CN palsy improved in 6/15(40%) patients treated with RT who had CN palsy at presentation. Three (12.5%) patients had

symptomatic progression but no radiological progression. No patient experienced RTOG grade III or more skin, mucosal toxicity or xerostomia at their last follow-up.

Conclusion Radiation therapy offers good local control with improvement in symptoms with acceptable toxicities and can be considered in initial decision making process.

Poster discussion: CL: Prostate 2

PD-0666 Prostate radiotherapy with Carbogen and Nicotinamide. Final results of the phase 1b/II PROCON trial K. Yip 1 , P. Hoskin 1,2 , N. Thiruthaneeswaran 2 , R. Alonzi 1 1 Marie Curie Research Wing, Mount Vernon Cancer Centre, Northwood Middlesex, United Kingdom ; 2 Manchester Cancer Research Centre, University of Manchester, Manchester, United Kingdom Purpose or Objective Prostate tumour hypoxia is associated with resistance to radiotherapy (RT) and increased likelihood of relapse post treatment. The concurrent administration of carbogen and nicotinamide (CON) with RT improves overall survival in patients with bladder cancer and regional control rates following laryngeal RT. We evaluated the safety, toxicity of this approach for patients with high risk prostate cancer. Material and Methods 50 patients (with 1 of: T3, Gleason ≥8, PSA ≥20) were recruited into the single arm phase 1b/II PROCON trial between Dec 2011 and Sept 2013. They breathed carbogen via a tight-fitting face mask during RT and took 60mg/kg of nicotinamide daily prior to the delivery of RT (74Gy/37# to the prostate and 60Gy/37# to the pelvic nodes). Twenty men also underwent functional MRI imaging; correction of tumour hypoxia was evaluated by comparing tumour R2* values before and after carbogen administration. Patients were assessed during treatment and 2, 4 and 12 weeks after they had completed RT. The primary endpoints were prevalence of grade 3 (G3) or worse lower gastrointestinal (GI) or genitourinary (GU) toxicities during this period. Secondary end points include PSA progression free survival (PFS) and overall survival (OS) rates at five years as calculated by the Kaplan Meier method. Results The median duration of follow up was 60 months. All patients completed the prescribed 37 fraction schedule of RT over 50 to 56 days (median duration: 52 days). 56% patients experienced grade 1 nausea (CTCAE v 4.0), and