Abstract Book

S223

ESTRO 37

(“ MirCor ”). For the remaining patients (21-30th for T1- T2, 21-27th for T3+) the extended atlas (consisting of 1- 20th cases with reference contour) was used to generate the same set of OARs (n=17). Time required for Man , Mir , MirCor were measured and compared using paired t-test. Delineations ( Man vs. Mir and MirCor ) were compared using Dice Similarity Coefficient (DSC), Jaccard index (JI), commonly contoured volumes (CCV) and 95% of the Hausdorff distance (HD95%). Since the Man and MirCor delineations are both clinically acceptable (e.g. intraobserver variability), and the DSC, JI and CCV values are volume dependent, relative values were used for Man vs. Mir . Baseline vs. extended m-ABAS performance was compared using two sided t-test with p<0.05 significance level. Results The average time for Man was 19.6±2.3 min, while Mir took an average of 16.2±2.1 min including 11.3±2.1 min for manual editing which represents the only effective work for RTTs (p<0.001).By increasing the number of atlas-cases a further 3 min gain was achieved per patient (p=0.009), leading to a >50% time reduction in OAR delineation. Time efficiency did not differ between early and advanced stage tumors (p=0.45) (Fig 1). The extended m-ABAS did not improve delineation performance significantly compared to baseline atlas, with the exception of the Brainstem’s CCV for early stage cohort (Table 1) .

Poster Viewing : Poster viewing 8: Head and neck

PV-0425 Associations between rash, treatment outcome, and SNPs in HNSCC patients receiving EGFR- inhibition L. Brøndum 1 , J. Alsner 1 , B. Singers Sørensen 1 , C. Maare 2 , J. Johansen 3 , H. Primdahl 4 , J. Folkvard Evensen 5 , C. Andrup Kristensen 6 , L. Juhler Andersen 7 , J. Overgaard 8 , J. Grau Eriksen 1 1 Aarhus University Hospital, Experimental clinical oncology, Aarhus C, Denmark 2 Herlev Hospital, Department of Oncology, Herlev, Denmark 3 Odense University Hospital, Department of Oncology, Odense, Denmark 4 Aarhus University Hospital, Department of Oncology, Aarhus C, Denmark 5 Oslo University Hospital, Dapartment of Oncology- Radiumhospitalet, Oslo, Norway 6 Rigshospitalet, Department of Oncology, Copenhagen, Denmark 7 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark 8 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus C, Denmark Purpose or Objective To study the associations between development of moderate to severe skin rash, clinical outcome, and single nucleotide polymorphisms (SNPs) in candidate genes in head and neck cancer patients from the DAHANCA 19 trial receiving the EGFR-inhibitor zalutumumab concurrently with radition treatment. Material and Methods 310 patients were included from the zalutumumab-arm of the DAHANCA 19 study. Nine SNPs in the candidate genes EGFR, EGF, AREG, FCGR2A, FCGR3A, and CCND1 were successfully determined in 294 patients. Clinical endpoints were moderate to severe skin rash within the first three weeks of treatment, loco-regional failure (LRF), disease specific survival (DSS), and overall survival (OS). Results During the first three weeks of treatment, 86% of the patients experienced any grade of rash and 17% experienced a moderate to severe rash. Development of moderate to severe rash was not associated with LRF or DSS but was associated with improved OS, HR 0.40 (95% CI: 0.19-0.82). The effect was similar for patients with p16-negative or p16-positive tumours (p=0.90). After adjustment for comorbidity and performance status, the minor alleles of SNPs rs9996584 and rs13104811 located near the AREG gene were significantly associated with increased risk of moderate to severe rash with per-allele odds ratios of 1.61 (1.01-2.54) and 1.56 (1.00-2.44). SNP rs13104811 located close to rs9996584 had a borderline significant association and none of the other SNPS were significantly associated with risk of skin rash. Conclusion Moderate to severe skin rash after zalutumumab during radiation treatment was associated with improved overall survival, independent of HPV/p16-status. Genetic variants in AREG (member of the EGF family) may be associated with increased risk of skin rash PV-0426 Prognostic value of CT based image biomarkers for treatment outcome in head and neck cancer patients T.T. Zhai 1,2 , L.V. Van Dijk 1 , J.A. Langendijk 1 , N.M. Sijtsema 1 , R.J.H.M. Steenbakkers 1 1 University Medical Center Groningen, Radiation Oncology, Groningen, The Netherlands

Conclusion M-ABAS with manual editing dramatically decreased delineation time for H&N OAR compared to manual delineation even with semi-automated options. Although the delineation accuracy did not improve significantly with extended atlases, still further time saving was achieved.