Abstract book - ESTRO meets Asia

S56 ESTRO meets Asia 2018

PO-142 Role of Adjuvant Radiotherapy in the Elderly with Localized Squamous Cell Carcinoma of Oral Tongue F.Y. Lin 1 , T.H. Chang 1 , M.T. Liu 1 , C.P. Pi 1 , C.C. Huang 1 , T.W. Chou 1 , J.B. Lin 1 1 Changhua Christian Hospital, Radiation Oncology, Changhua City, Taiwan Purpose or Objective Curative surgical resection followed by adjuvant radiation therapy, if risk factors of recurrence were present, remained the standard of care in patients with localized squamous cell carcinoma of oral cavity. However, the absolute benefit of adjuvant radiotherapy in elderly patients is still unclear. The aim of the current study is to investigate the treatment outcome and effect of adjuvant radiation therapy in the elderly with localized squamous cell carcinoma of oral tongue. Material and Methods We performed systemic chart review and identified 115 patients aged ≥ 65 with localized squamous cell carcinoma of oral tongue treated at our institution between 2007 and 2015. Recurrence and survival outcomes were analyzed using Kaplan-Meier method and log rank test based on treatment modalities. Results With mean age of 72 (range 65-87), eighty-six (74.8%) of all 115 patients received surgery alone; otherwise the remainders (n=29, 25.2%) underwent surgery followed by adjuvant radiotherapy. The 3-year recurrence-free survival was 69.8% in patients treated with surgery alone, and 86.2% in patients treated with surgery followed by adjuvant radiotherapy (p=0.54). The 3-year overall survival is 53.5% in patients received surgery alone and 55.2% in patients treated with surgery and adjuvant radiotherapy (p=0.13). Conclusion In the elderly patients diagnosed with localized squamous cell carcinoma of oral tongue, those who received surgery alone as primary treatment presented a trend towards higher 3-year recurrence rate; although there is no difference in 3-year overall survival compared with patients treated with surgery followed by adjuvant radiotherapy. Developing a risk-based strategy which incorporates co-morbidities and/or life expectancy is needed for guiding adjuvant radiotherapy in elderly patients with localized squamous cell carcinoma of oral tongue. PO-144 Clinical outcomes and dose-volume predictors of hypothyroidism in head and neck malignancies V. Pareek 1 , R. Bhalavat 1 , M. Chandra 1 , L. Nellore 1 , K. George 1 , D. Borade 1 , K. Kalariya 1 , R. Navaneeth 1 , Z. Moosa 1 , A. Srivastava 1 , A. Kapoor 1 , D. Kawale 1 , P. Bauskar 1 1 Jupiter Hospital, Radiation Oncology, Mumbai, India Purpose or Objective Radiation therapy to head and neck malignancies has a significant impact on the dose to thyroid gland and thereby causing dysfunction of the organ and leading to subclinical or clinical hypothyroidism. The objective of this study was to understand better the associated risk factors for development of hypothyroidism, the onset period, association of patient and treatment related parameters and also the dosimetric parameters leading to hypothyroidism in initial euthyroid head and neck PO-143 How do we use neck node data? Abstract withdrawn

malignancies receiving radiation therapy. The role of treatment techniques with Three-dimensional conformal radiotherapy (3DRT) and Intensity modulated radiotherapy (IMRT) was also assessed for better clinical outcomes with respect to development of hypothyroidism. Material and Methods In our prospective, non-randomized, observational study, during the period September 2015 to April 2017, a total of 350 patients with histopathologically proven head and neck squamous cell cancer of various sites, were enrolled as subjects for the study. The cohort included 213 males and 137 females with a median age of 51.5 years (Range 22 – 68 years). The patients received radiation therapy with a median dose of 60Gy (Range 60 - 66Gy) with either IMRT or 3DCRT techniques. Thyroid function was assessed at baseline and thereafter at 6 and 12 months following the completion of radiotherapy. Detailed thyroid dosimetric parameters including maximum, minimum and mean dose (Dmax, Dmin, Dmean) and other dose and volume parameters (e.g. D10, D20, D50 and V10 – V50) were assessed through the cumulative dose volume histograms (DVH). Multivariate analysis and other appropriate statistical analysis were done to determine the factors associated with the development of subclinical and clinical hypothyroidism and correlation with dosimetric parameters. Results After a median follow up of 24 months, the incidence of subclinical hypothyroidism at 6 months of completion of treatment was 3.3% and incidence of clinical hypothyroidism was 1.3%. Among general parameters, nodal burden (p = 0.003), chemotherapy (p < 0.001) and tobacco addiction (p = 0.013) were found to be significant risk factors in subsequent development of hypothyroidism. On assessment of dosimetric parameters, on univariate analysis, minimum dose was found to be statistically significant along with V25 – V50 and D10, D20 and D50 parameters. On multivariate analysis, V30 (p = 0.002), V40 (p = 0.0004) and V50 (p = 0.0002) were the most statistically significant. IMRT was found to have much lower incidence of development of hypothyroidism compared to 3DCRT (p = 0.0489). Conclusion In head and neck squamous cell carcinoma patients treated with radiation therapy, thyroid minimum dose, V30, V40 and V50 and use of chemotherapy and initial nodal burden and tobacco addiction are risk factors for development of subclinical or clinical hypothyroidism and can be used as predictors for such outcomes. PO-145 HDR Interstitial brachytherapy in Recurrent head and neck cancer: An effective treatment modality V. Pareek 1 , R. Bhalavat 1 , M. Chandra 1 1 Jupiter Hospital, Radiation Oncology, Mumbai, India Purpose or Objective High Dose Rate (HDR) Interstitial Brachytherapy has an established role in head and neck malignancies and offers good survival rates, however, there are scant data on improved local control (LC) and treatment-related complications in patients with recurrent head and neck (H&N) cancers. We report our results in patients with recurrent H&N cancers treated with interstitial HDRBT. Material and Methods Twenty-Five patients with recurrent H&N cancers were treated with HDR interstitial brachytherapy between January 2010 and December 2016. Of these, 75% received radical brachytherapy and 25% received external beam radiation therapy (EBRT) followed by brachytherapy boost. The treatment sites were oral cavity (15/25) and oropharynx (10/25). The median dose was 4.5 Gy twice per day with median total dose with brachytherapy of 40.5Gy in radical and 27Gy for EBRT cases. The EBRT median total was 46Gy. HDR Interstitial Brachytherapy