ESTRO 38 Abstract book

S662 ESTRO 38

Regarding to toxicity, 55% (n= 160) of the patients presented acute pharyngo-esophageal toxicity grade 3 to 5 (CTCAE v4.0). Chronic toxicity greater or equal to grade 3 (RTOG escale) was presented in 15.5% of patients. The 5-year cumulative incidence of TM was 39.7%: 36.4% corresponding to primary tumor-death and 3.3% to second tumor-death. The predictors factors of TM were: poor performance status (ECOG 1-2 vs 0; HR 1.52), advanced stage (IVA-B versus III; HR 1.8) and non-CRT treatment versus concurrent CRT regimens (HR 1.76). The 5-year cumulative incidence of CM was 11.8%. The incidence to CM secondary to acute and chronic toxicity were 5.5% and 1.5%, respectively. The cumulative incidence of death related to comorbidity was 4.4% (Figure 1). In the multivariate analysis the predictors factors of CM were increased age (HR 1.05) and comorbidity (HR 3.03). Patients with moderate to severe comorbidity presented a CM risk three times higher than those patients with mild or without comorbidity (Table 1). Acute mucositis grade 3 to 5 was associated with CM in the bivariate analysis but not in the multivariate analysis.

3 European Institute of Oncology, Division of Epidemiology and Biostatistics Unit, Milan, Italy ; 4 University of Turin, Department of Oncology- Radiation Oncology, Turin, Italy ; 5 University Hospital- Novara, Division of Radiation Oncology, Novara, Italy ; 6 European Institute of Oncology, Division of Oncology, Milan, Italy ; 7 ICS Maugeri- I.R.C.C.S, Unit of Radiation Oncology, Pavia, Italy ; 8 University of Milan, Department of Oncology and Hemato-oncology, Milan, Italy Purpose or Objective To compare radiation-induced acute toxicity in patients (pts) affected by locally advanced nasopharyngeal cancer (NPC) treated with sequential intensity modulated radiotherapy (IMRT) and proton therapy boost (mixed beam-MB approach) with an historic cohort of pts treated with a full course of only IMRT. Material and Methods From June 2012 to November 2017, 27 consecutive pts with locally advanced NPC (cT3-4, any N, M0) were treated with MB approach. It consisted in a first phase of treatment performed with IMRT up to 54-60 Gy followed by a second phase performed by proton therapy boost (with pencil beam scanning) up to 70-74 Gy RBE (Relative Biological Effectiveness) prescribed to the macroscopic disease according to the pre-treatment radiologic images. This cohort were compared to an historic cohort of 17 consecutive pts treated with only IMRT only. Pts treated with IMRT only received a total dose of 69.96 Gy. A standard fractionation schedule (1.8-2.12 Gy/fraction, 1fraction/day, 5 fractions/week) was used in both cohorts. Concurrent (with or without induction) platinum- based chemotherapy was administered in all pts. The acute-toxicity profile was considered as the worst event occurred during the entire course of treatment according to Common Terminology Criteria Adverse Events V4.03 scale. Results The 2 cohorts of pts were comparable with no significant differences regarding clinical parameters. The prescribed total dose was significantly higher (p=0.02) in pts treated with MB compared to those treated with only IMRT only. Acute grade 3 mucositis and grade 2 xerostomia were found in 11% and 76% (p=0.0002) and 7% and 35% (p=0.02) of pts treated with MB and IMRT, respectively. No other significant differences were found among the analyzed parameters. For MB cohort median follow-up was 25 months. All but one pts achieved complete tumor response and no patients developed local and/or regional recurrences. At last follow up, 22 22 pts were still alive with no evidence oft disease. For IMRT only cohort median follow-up was 51 months. One patient died one week after the end of radiotherapy for treatment-related toxicity. One patient did not achieve a complete response to treatment on the primary tumor. He progressed on both primary tumor and neck lymph node and died 19 months from the end of treatment. Three patients experienced tumor local progression after 19, 51 and 82 months, respectively; 2 pts experienced also lymph node recurrences and 1 patient also lymph node metastasis Conclusion Our results suggest that sequential MB approach for locally advanced NPC pts is safe with an excellent acute toxicity profile. Preliminary results on clinical outcome are encouraging but need to be confirmed in lager cohort of pts with a longer follow-up EP-1195 Functional assessment of late toxicity and quality of life after IMRT for sinonasal carcinoma M.B. Sharma 1 , K. Jensen 2 , S.F. Urbak 3 , M. Funding 3 , A. Amidi 4 , C. Grau 5 1 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark ; 2 Aarhus University Hospital, Danish Center for Particle Therapy, Aarhus, Denmark ; 3 Aarhus University Hospital, Department of Ophthalmology,

Figure 1: 5-year cumulative incidences of causes of death.

Table 1: Multivariate analyses of predictors factors of competing and tumor mortality. Conclusion This study demostrates an important incidence of competitive deaths in patients with LAHNC treated with combined treatments. Among the factors that predict these deaths, age and, especially, moderate-severe comorbidity have been identified. Tumor deaths were associated with poor performance status, stage IV, and concurrent RT plus anti-EGFR. All these factors must be considered especially in the choice of the combined treatment of patients with LAHNC. EP-1194 Acute toxicity in nasopharyngeal cancer patients treated with IMRT followed by proton therapy boost D. Alterio 1 , E. D'Ippolito 2 , B. Vischioni 2 , R. Ricotti 2 , S. Gandini 3 , M. Bonora 2 , V. Vitolo 2 , E. Mastella 2 , G. Magro 2 , S. Ronchi 2 , P.F. Franco 4 , U. Ricardi 4 , M. Krengli 5 , S. Comi 1 , E. Verri 6 , G. Ivaldi 7 , B.A. Jereczek-Fossa 1,8 , F. Valvo 2 , R. Orecchia 1,2 1 European Institute of Oncology, Division of Radiation Oncology, Milan, Italy ; 2 National Center of Oncological Hadrontherapy, Radiotherapy Unit, Pavia, Italy ;