ESTRO 36 Abstract Book

S304 ESTRO 36 _______________________________________________________________________________________________

with respect to clinicopathological criteria poses a dilemma for patient selection.The purpose of this study is to analyze clinical outcomes of patients treated with APBI using multi-catheter interstitial brachytherapy (MIB-APBI) stratified as per GEC-ESTRO and ASTRO guidelines for patient selection and to correlate and analyze appropriateness of these criteria for grouping patients to predict clinical outcomes. Material and Methods Two hundred and forty two women underwent MIB-APBI during July 2000- March 2013. Comparison of patient selection criteria as per GEC-ESTRO and ASTRO guidelines and their clinical outcomes was done on a prospectively maintained database. Median age was 56 years, and median pathological tumor size was 2 cm. ER, PR and HER 2 receptor positivity was seen 58.3%, 53.7% and 10.7% patients respectively. Median number of planes was 3 and median dose of APBI was 34 Gy. Kaplan Meier survival analysis was done for local control (LC), disease free survival (DFS), cause specific survival (CSS) and overall survival (OS) after sub grouping as per both GEC-ESTRO and ASTRO consensus guidelines. Results As per analyses with ASTRO consensus for patient selection, our cohort consisted of 32 (13.2%), 143 (59.1%) and 67(27.7%) patients belonging to suitable, cautionary and unsuitable group, respectively. According to ESTRO guidelines, 148(61.2%), 54(22.3%) and 40 (16.5%) patients were categorized as low, intermediate and high risk group, respectively. At a median follow up of 90 months, 7 year overall LC, DFS, CSS and OS were 94.3%, 88%, 97% and 92.2% respectively for the entire group. There was no statistically significant difference in the LC rates for both ASTRO and ESTRO consensus groups (Table1 ). Thirty five patients (14%) had disease failure out of which 12 patients failed loco-regionally. The DFS (p=0.008), CSS (p=0.004) and OS (p=0.007) rates were significantly correlated with GEC-ESTRO consensus guidelines for patient selection while none of our outcomes correlated with ASTRO consensus guidelines. Variable cut off for age, tumor size and weightage for presence of lymphovascular emboli in these two guidelines mainly led to differences in the distribution of risk stratification.

Pancreas cancer patients, most of which present with late stage therapy-resistant pancreatic ductal adenocarcinoma (PDAC), still have a very poor prognosis. A mere five percent will survive for five years after being diagnosed. Throughout all stages of pancreatic cancer, from oncogenesis to treatment follow-up, using radiopharmaceuticals with PET or SPECT imaging can have significant impact on the management of pancreatic cancer patients. An overview of PET and SPECT imaging techniques will be presented, combining reports from the literature with our own recent work. Some are already in clinical use; some very novel agents have shown promise in the preclinical stage. A small segment will be dedicated to the use of therapeutic radiopharmaceuticals. SP-0571 State of the art precision medicine for benign and malignant brain tumours G. Zadeh 1 1 University Health Network, Toronto, Canada SP-0572 Circulating tumour DNA, a new tool for the early detection of poor outcome F.C. Bidard 1 1 Institut Curie, Paris Cedex 05, France Owing to the development of techniques that can detect rare variants, circulating tumor DNA is now approved or under investigation as a circulating tumor biomarker for several applications in clinical oncology. ctDNA can be used as “liquid biopsy”, surrogate to tissue biopsy (such as in e.g. NSCLC for EGFR mutation detection), but is also investigated as a dynamic marker of tumor load which may be relevant for early detection of relapse or resistance to therapy. This presentation will focus on how ctDNA can be used to detect early relapse/resistance, with examples from studies initiated by our group: - TP53 mutation detection: results obtained in locally advanced triple negative breast cancer (Riva et al , in press) and ongoing "CirCA-01" study testing the early detection of relapse and new tumor growth in BRCA01 mutation carriers (NCT02608346) - HPV detection: results obtained in metastatic patients and ongoing "CirCA-HPV" study testing the early detection of relapse in cervix and anal canal cancers - ESR1 mutation detection: ongoing PADA-1 phase III trial testing the utility of ESR1 mutation detection in metastatic HR+ breast cancer OC-0573 Development of hypoxia gene signatures as biomarkers for treatment stratification C. West 1 , L. Yang 1 , D. Roberts 1 , B. Bibby 1 , L. Forker 1 , S. Haider 2 , F. Buffa 2 , A. Choudhury 3 1 The University of Manchester, Translational Radiobiology Group, Manchester, United Kingdom 2 University of Oxford, Computational Biology and Integrative Genomics, Oxford, United Kingdom 3 Christie Hospital NHS Trust, Clinical Oncology, Manchester, United Kingdom Purpose or Objective A promising area for the development of biomarkers for radiotherapy stratification is gene expression profiling to predict benefit from hypoxia modification. Advantages of RNA signatures versus other approaches are their good repeatability and ability to minimise intra-tumour variability. The rationale for focusing on hypoxia is that interventions are available with proven benefit when added to radiotherapy. This work investigated the transferability of published signatures across tumour types and the benefit of deriving tumour specific profiles. Abstract not received

Conclusion Patient selection as per both ESTRO and ASTRO consensus guidelines do not have any impact on local control rates for patients treated with APBI using interstitial brachytherapy at long term follow up.

Symposium with Proffered Papers: Novel approaches in poor tumour control sites

SP-0570 Radiopharmaceuticals in pancreatic cancer: imaging and therapy B. Cornelissen 1 1 University of Oxford- CRUK/MRC Oxford Institute for Radiation Oncology, Radiopharmaceuticals and Molecular Imaging Group, Oxford, United Kingdom The potential of nuclear medicine imaging and therapy will be discussed, with a focus on pancreatic cancer.