ESTRO 36 Abstract Book

S315 ESTRO 36 _______________________________________________________________________________________________

Poster: Clinical track: Head and Neck

Purpose or Objective Purpose : In locally advanced oropharyngeal cancer (LAOC) treated with definitive radiotherapy (RT), the aims of this study were: (1) to identify PET-FDG parameters correlated with overall survival from a first training patients and therefore to compute a prognostic score; and (2) to validate this scoring system in a second independent cohort of patients. Material and Methods A training cohort including 76 consecutive LAOC patients treated with chemoradiotherapy or with cetuximab in a first Cancer Center were analyzed. A predictive model of loco-regional control (LRC) and overall survival (OS) was built based on PET-FDG parameters. After internal calibration and validation of the model, a nomogram and a scoring system were developed, and tested in a validation cohort of 46 consecutive patients treated in a second Cancer Center. Results The two populations differed notably concerning age (mean 59 .2 vs 63.3 years [p = 0.02]) the tumor volume (GTV: 45.8 cm 3 vs 25.6 cm 3 [p <0.001]), p16 status (p16+: 18% vs 37%, [p = 0.001]) for the training and validation cohort, respectively. The median follow-up for the training cohort and validation cohort were 38 (range, 2- 80) and 23 months (range, 3- 57 months), respectively (p<0.001). The 2-year OS rate was 58% (95% CI: 46-70%) and 85% [74-99%] for the training and the validation cohort, respectively (p=0.001). In multivariate analysis, the metabolic tumor volume (MTV) of the primary tumor and the lymph nodes were independent predictive factors for LRC and OS. Internal calibration showed a very good adjustment between the predicted OS and the observed OS at 24 months. A prognostic score was calculated, based on the β-parameter from the Cox model. A normalization was applied to obtained a score ranging from 0- 5. Using the predictive score, two risk groups (cut-off = 1.33) were identified (median OS 42 vs 14 months, p<0.001) and confirmed in the validation cohort (median OS not reached vs 26 months, p=0.008) (Figure).

PO-0603 Metachronous Second Primary Head and Neck Squamous Cell Carcinoma S.Y. Wu 1 1 Taipei Medical University Hospital, No.111- Section 3 Department of Radiation Oncology, Taipei, Chinese Taipei Purpose or Objective The optimal therapeutic decisions for metachronous second primary head and neck squamous cell carcinomas (mspHNSCCs) are unclear. We examined the treatment outcomes of a national cohort to determine suitable treatments and prognostic factors in patients with mspHNSCCs at different stages and sites. Material and Methods We analyzed data of >20-year-old patients with HNSCC at American Joint Committee on Cancer clinical stages I–IV without metastasis collected from Taiwan Cancer Registry databases. Our protocols were reviewed and approved by the institutional review board at Taipei Medical University ( TMU-JIRB No. 201402018). The patients were categorized into four groups based on the treatment modality: Group 1 (control arm, chemotherapy [CT] alone), Group 2 (reirradiation [re-RT] alone with intensity modulation radiotherapy [IMRT]), Group 3 (concurrent chemoradiotherapy [CCRT] alone [irradiation with IMRT]), and Group 4 (salvage surgery with or without RT or CT) Results We enrolled 31 762 HNSCC patients without mspHNSCCs and 1741 mspHNSCCs patients without distant metastasis . Univariate and multivariate Cox regression analyses revealed that surgery, CCRT, Charlson comorbidity index (CCI) ≥6, stage of second HNSCC, stage of first HNSCC, and duration from first primary HNSCC of >3 years were significant independent prognostic risk factors for overall survival. After adjustment, adjusted hazard ratios (aHRs; 95% confidence intervals [CIs]) for overall mortality at mspHNSCCs clinical stages I and II were 0.91 (0.42-01.98, P = .806), 1.34 (0.78-2.29, P = .284), and 0.60 (0.38-0.96, P = .033) in Groups 2, 3, and 4, respectively; those for overall mortality at mspHNSCCs clinical stages III and IV were 0.72 (0.40-1.82, P = .255), 0.52 (0.35-0.75, P < .001), and 0.32 (0.22-0.45, P < .001) in Groups 2, 3, and 4, respectively. A Cox regression analysis indicated that a re- RT dose of ≥6000 cGy was an independent protective prognostic factor for treatment modalities. Conclusion Salvage surgery is recommended for mspHNSCCs if a patient is operable. However, if the patient is inoperable, CCRT is recommended rather than re-RT or CT alone. A re- RT dose of ≥6000 cGy may be necessary for mspHNSCCs. PO-0604 A PET-based nomogram to predict survival in oropharyngeal cancers radiotherapy J. Castelli 1 , A. Depeursinge 2 , V. Ndoh 1 , J.O. Prior 3 , M. Ozsahin 4 , A. Devillers 5 , E. Chajon 1 , R. De Crevoisier 1 , N. Scher 4 , F. Jegoux 6 , E. Vauleon 7 , B. De Bari 4 , J. Bourhis 4 1 Centre Eugène Marquis, Radiation Oncology, Rennes CEDEX, France 2 University of Applied Sciences Western Switzerland, University of Applied Sciences Western Switzerland, Sierre, Switzerland 3 CHUV, Nuclear Medicine and Molecular Imaging Department, Lausanne, Switzerland 4 CHUV, Radiation Oncology, Lausanne, Switzerland 5 Centre Eugène Marquis, Nuclear Medicine and Molecular Imaging Department, Rennes CEDEX, France 6 CHU Rennes, Head and Neck department, Rennes, France 7 Centre Eugène Marquis, Oncology, Rennes CEDEX, France

Conclusion Conclusions: This is the first report of a PET-based nomogram in oropharyngeal cancer. Interestingly, it appeared stronger than the classical prognostic factors and was validated in independent cohorts markedly diverging in many aspects, which suggests that the observed signal was robust. PO-0605 Factors associated with late dysphagia and xerostomia in (chemo)radiation for head and neck cancer. F. Duprez 1 , L. De Witte 2 , S. Nuyts 3 , S. Deheneffe 4 , D. Van Gestel 5 , M. Voordeckers 6 , H. Thierens 2 , W. De Neve 7 , K. De Ruyck 2 1 University Hospital Ghent, Radiation Oncology, Gent, Belgium 2 Ghent University, Basic Medical Sciences - Medical Physics, Ghent, Belgium