Small cell carcinoma (SmCC) of the vagina is a rare and aggressive tumour. It comprises only 1% –2% of all gynaecological malignancies 85% of the patients with SmCC vagina die within a year of diagnosis. Here we report the case of a 65-year-old woman with stage III primary neuroendocrine carcinoma of vagina who was treated with chemoradiotherapy. The patient survived 1 year and 10 months after the initial presentation. SmCC of the vagina is very rare and despite being aggressive, the local disease can be controlled with a chemoradiation regimen.

Introduction:The complexity of modern-day radiotherapy techniques calls for greater accuracy in target volume delineation which requires intensive training and expert guidance. In this study, we intend to evaluate the status of training in target delineation across radiation oncology curriculums in India and utility of webinars in teaching it. Methodology: We organized daily webinars on the topics of radiological anatomy and target volume delineation in common sites of cancer over a period of 2 weeks. At the end of the program, a 35 item survey questionnaire was shared with the participants. The responses were analysed and are reported here. Results: Out of the 797 participants that registered for the course, 356 radiation oncologists responded to the survey questionnaire. Majority (96%) of our respondents believe that there is a need for additional training in target volume delineation. Ninety percent of the participants felt that radiation oncology curriculum requires a formal radiology training but only 6.7% reported that their training consisted of a dedicated rotation and regular lectures in radiological anatomy. Majority (97%) responded that they were likely to incorporate the points learnt from the webinar sessions in their daily practice. Forty eight percent of respondents opted for attending a webinar to an in-person event in the future while 34% would like to have the option to choose between the two. Ninety four percent agreed that online webinars should be conducted routinely even after the pandemic ends. Conclusion: Our survey results suggest that target volume delineation training in India is deficient and virtual teaching programs can be a practical and effective way to improve it.

Abstracts iii119NEURO-ONCOLOGY • MAY 2017 extracted and XRCC1 gene SNPs were analyzed; the allelic discrimination was performed using an ABI PRISM 7900 SDS (Applied Biosystems, Carlsbad, CA, USA) and with validated TaqMan ® SNP genotyping assays (Applied Biosystems). Kaplan Meier curves were performed for statistical association with genotypes. The study has been approved by the local IRB. RESULTS: At the data analysis, the median progression-free survival (PFS) and median overall survival (OS) of these patients were 20 months and 11 months, respectively. A relevant finding of our study was the identification of a XRCC1 genotype that was significantly associated with OS: patients harboring the TT or CC genotype had 12 and 24-month OS ratio of 75 and 16%, respectively, whereas, patients with genotype TC 88 and 34%, respectively. CONCLU-SIONS: The XRCC1 genotype is significantly associated with a shorter OS in GBM patients treated with radiotherapy and temozolomide schedule. The present, pilot study may represent the stimulus to prospectively investigate the role of XRCC1 polymorphisms as a predictive pharmacogenetic marker or as a target for new drug therapies for GBM patients. P17.13 DOSIMETRIC COMPARISON AND FEASIBILITY OF SIMULTANEOUS INTEGRATED BOOST (SIB) IN TREATMENT OF MALIGNANT GLIOMAS USING INTENSITY MODULATED RADIOTHERAPY (IMRT) OR VOLUMETRIC MODULATED ARC THERAPY (VMAT)P. Rapole, G. Karunanidhi, S. Kandasamy, G. Ram Kumar, Sathia Prabhu; Jawaharlal Institute of Post-Graduate Medical Education and Research, Puducherry, India.OBJECTIVE: Simultaneous integrated boost(SIB) is a hypo-fractionation technique wherein the tumor receives different doses to different areas in a single fraction. In our study, we have evaluated the dosimetric feasibility of SIB in the treatment of malignant gliomas and compared the SIB plans of VMAT and IMRT. METHODOLOGY: The patient's MRI (taken four weeks after surgery) and planning CT were used for generating SIB plans with VMAT and IMRT. GPTV is defined as the tumor edema in FLAIR plus a margin of 5 mm. CPTV is defined as the GPTV plus a margin of 2 cm. A dose of 2Gy per fraction was prescribed to the CPTV and 2.4Gy to the GPTV for a total of 25 fractions. The plans were accepted only if they met the set of planning objectives defined in the protocol. The feasibility of SIB planning was evaluated, and the dosimetric data of VMAT and IMRT for SIB planning was compared. RESULTS: The GPTV coverage was significantly better in VMAT than in IMRT (98.67% vs 98.19%;p=0.024). The conformity index for GPTV in IMRT was higher than that of VMAT (0.83 vs 0.76; p=0.001). In contrast to what observed in GPTV, the percentage coverage of CPTV was better in IMRT (97.88% vs 96.87%; p=0.021). But the conformity index of CPTVannulus was higher in VMAT (0.72 vs 0.67; p=0.01). There was no difference in homogeneity index of GPTV and CPTV annulus between the plans. The mean dose received by Normal brain was higher in IMRT than in VMAT (28Gy vs 24.2Gy; p<0.001). Ipsilateral optic nerve has received...

Background: Radiotherapy after breast conserving surgery includes irradiation of whole breast and regional lymphatic areas which is followed by a boost to the tumor bed. Several different techniques have been proposed for delineation of tumor bed for boost. The purpose of the study was to identify the best method for localizing the tumor bed. Methods: 21 patients with histologically proven stage I and II infiltating ductal carcinoma of breast who underwent breast conserving surgery were included in the study. We delineated the boost volumes using five different techniques viz., patients’ self-localization, surgeon’s localization, pre-op CT based, scar-based and surgical clips based. The surgical clips-based volume is taken as a standard volume and the other volumes were compared with it. The outcome measures studied were the mean overlap volumes, the mean volume of surgical clips based volume missed by the other PTVs, the mean volumes of breast tissue outside the clips based PTV that could have been irradiated by the other PTVs. Results: None of the PTV volumes had good concordance with the surgical clips-based volume (PTV1). The best volume overlap was with patient’s self-localization (PTV3) albeit only being 34%. The scar-based localization volume had the least overlap with PTV1 (23%). The patients’ self-localization volume (PTV3) had the highest amount of breast tissue included outside PTV1 (64cc) and preop CT based volume (PTV4) included the least (42cc). Conclusion: Delineation of boost volume using surgical clips augmented by the simulation CT should be the standard technique for boost bed irradiation.