Abstract Book

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ESTRO 37

5 European Institute of Oncology, Advanced Radiotherapy Center, Milan, Italy 6 Brescia University- Istituto del Radio "O. Alberti-" Spedali Civili Hospital, Radiation Oncology Department, Brescia, Italy 7 IRCCS A.O.U.San Martino - IST -Istituto Nazionale per la Ricerca sul Cancro, Radiation Oncology Department, Genoa, Italy 8 Istituto Nazionale per lo studio e la cura dei Tumori - Fondazione "G. Pascale", Radiation Oncology Department, Naples, Italy Purpose or Objective Patient selection for re-irradiation (re-RT) in recurrent or second primary Head and Neck cancer (rHNC) remains challenging. We investigated the impact of clinical, disease and treatment related factors on the progression free survival (PFS) and overall survival (OS) of rHNC patients (pts) receiving curative re-RT. Material and Methods A retrospective study was performed on 159 patients with rHNC treated at 7 Italian tertiary cancer centers on behalf of Italian Association of Radiation Oncology (AIRO) Head and Neck Working Group. Inclusion criteria were: previous curative RT (66-70 Gy); postoperative or definitive re-RT (3DCRT, IMRT or SBRT) with or without concomitant chemotherapy (CHT); time interval of >6 months between two courses of radiation; minimum follow-up after re-RT at least 6 months; re-RT given with conventional fractionation (CF <2,2 Gy per fraction) or hypofractionation (hypoF≥2.2) to a total BED of at least 45 Gy (alpha/beta=10, BED 10 ); fully available dosimetric and clinical data. Sarcoma and melanoma were excluded. The endpoints analyses were OS and PFS, both considered from the re-RT starting date. Survival curves were estimated with the Kaplan-Meier method. Univariable and multivariable Cox analyses were also performed; variable selection in the latter was performed using random forest models. Optimal volume of recurrence (VRec) and BED cut-offs to classify pts as high versus low risk for OS or PFS were determined according to Mandrekar et al. Toxicity profiles were evaluated according to CTCAE vs. 4.0 criteria. Results Median age was 61 years (range, 19-93) and 67% were males. Primary site were nasopharynx (NP) and oral cavity in 30% and 12% of pts, respectively. Histology was squamous cell carcinoma (SCC) in 55% of pts. Recurrence stage was IV in 57% of pts; KPS was <80 in 15%; 88% of pts had no organ dysfunction; 26% of pts had a Charlson Comorbidity Index score ≥2. Re-RT technique was IMRT and SBRT in 40% and 24%, respectively; CF was used in 71% of pts. Median VRec was 32.12 cc and median BED 10 was 58.6 Gy. Thirty-one% of pts received concomitant CHT. Median follow-up was 49.9 months (interquartile range, 28.9-86.3). Two- and 5-year OS and PFS were 75% and 42% and 49% and 19%, respectively. Univariable analysis results are shown in Table 1. At multivariate analysis NP site, higher KPS, no organ dysfunction, histology other than SCC, VRec ≤ 36cc were significantly associated with higher OS (Table 2). Histology other than SCC, BED 10 >52 Gy and VRec ≤ 7.9cc were favourable independent prognostic factors for PFS. Grade 3 acute and late toxicity rates were 12% and 6%, respectively.

Taoyuan, Taiwan 7 Chang Gung Memorial Hospital, Medical Oncology, Taoyuan, Taiwan Purpose or Objective The most recent American Joint Committee on Cancer (AJCC 2017, eighth edition) staging manual modified the T classification of patients with tongue squamous cell carcinoma (SCC). Specifically, the presence of extrinsic tongue muscle invasion does not longer be classified as a T4 disease. However, this approach may be debatable as it can lead to tumor downstaging. To investigate whether this is actually the case, we designed a nationwide study to compare the clinical outcomes of Taiwanese patients with tongue SCC staged as pT3 versus pT4 based on the former AJCC 2010 seventh edition criteria. Patients with pT1 and pT2 tumors served as reference categories for survival analyses. Material and Methods Using data collected from the Taiwanese Cancer Registry Database between 2004 and 2012, we examined 8,509 patients with first primary tongue SCC who received surgery with or without adjuvant therapy. The distribution of T classification was as follows: pT1, n = 3,618; pT2, n = 3,043; pT3, n = 766; and pT4, n = 1,082. Results Less favorable 5-year outcomes were observed in patients with pT4 malignancies than in those with pT1-pT3 tumors (disease-specific survival [DSS], 53%/89%/74%/64%; overall survival [OS], 43%/82%/67%/56%, respectively, p <0.0001; pT4 versus pT3, p <0.0001). The presence of pT4 disease (versus pT3) was identified as an unfavorable independent prognostic factor for both DSS and OS.

Conclusion Patients with pT4 tongue SCC have a less favorable prognosis than other T categories. Cases with tongue SCC and extrinsic muscle invasion should continue to be classified as having pT4 tumors. PV-0432 Impact of re-irradiation volume and dose on the survival of recurrent HN cancer: an AIRO study E. Orlandi 1 , R. Miceli 2 , G. Infante 2 , E. D'Angelo 3 , P. Bonomo 4 , D. Alterio 5 , M. Maddalo 6 , A. Bacigalupo 7 , A. Argenone 8 , N. Iacovelli 1 , C. Fallai 1 , N. Facchinetti 1 , S. Naimo 1 1 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiation Oncology 2, Milan, Italy 2 Fondazione IRCCS Istituto Nazionale dei Tumori, Unit of Medical Statistics- Biometry and Bioinformatics Unit of Clinical Epidemiology and Trial Organization, Milan, Italy 3 Policlinico di Modena, Radiation Oncology Unit, Modena, Italy 4 Azienda Ospedaliero-Universitaria di Careggi, Radiotherapy Department, Florence, Italy