ESTRO 38 Abstract book

S346 ESTRO 38

(ypT0-1 ypN0). Moreover, new radiation techniques such as SBRT allow dose escalation to the target volume while improving sparing of nearby normal structures. Combined with more effective chemotherapy regimens, it should improve the outcome of these patients. SP-0659 Against the motion: locally advanced pancreatic cancer E. Van Cutsem 1 University Hospital Gasthuisberg, Leuven, Belgium

#VU2010-4874 and STOPHersentumoren.nl, grant #2015- 009.

Debate: This house believes that there is still a role for radiotherapy in pancreatic cancer

SP-0656 For the motion: resectable pancreatic cancer T.Brunner 1 1 Otto-von-Guericke-Universität Dept. Radiation Oncology, Magdeburg,Germany

Abstract not received

Abstract not received

Symposium: New developments in Head and Neck Cancer treatment

SP-0657 Against the motion: resectable pancreatic cancer M. Falconi 1 1 San Raffaele Hospital, Pancreas Surgery, Milano, Italy Abstract text The management of resectable pancreatic cancer is challenging and different strategies can be applied including upfront surgery followed by adjuvant therapy or neoadjuvant treatment followed by surgical resection. This decision is based on the presence of an anatomical and/or biological borderline resectable tumor. In the setting of neoadjuvant treatment, there is a lack of evidence that support the routine use of preoperative radiation therapy with chemotherapy, especially when considering multi-agents chemotherapy regimens (i.e. FOLFIRINOX; gemcitabine plus nab-paclitaxel). The rationale for preoperative chemoradiation is related to a lower rate of R1 resection rate following radiation therapy, but actually no RCT showed a real advantage of this approach over chemotherapy alone. In the setting of adjuvant treatment, there is an unclear role for adjuvant radiotherapy, that is most likely recommended for patients with a R1 resection. Most studies did not find any advantage in the survival rate following chemoradiation compared to adjuvant chemotherapy alone. However, several studies administered suboptimal and obsolete schedule of radiotherapy and/or included small cohorts of patients, and as a consequence this represents a major limitation of any comparison of chemoradiation versus chemotherapy alone, both in the adjuvant and neoadjuvant setting. Novel radiotherapic approaches including stereotaxic body radiation therapy should be evaluated in powered randomized clinical trial considering specific aims (local recurrence, overall survival, toxicity). SP-0658 For the motion: locally advanced pancreatic cancer F. Huguet 1 1 Hôpital Tenon, Department of Radiotherapy, Paris Cedex 20, France Abstract text At diagnosis, about 25% of patients with pancreatic adenocarcinoma presents with a locally advanced (non- metastatic but unresectable due to vascular invasion) or borderline resectable tumor. Despite the technical progress made in the field of radiation therapy and the improvement of the efficacy of chemotherapy, the prognosis of these patients remains poor. Recently, the role of radiation therapy in this setting has been much debated. However, some arguments support the use of radiation therapy for these patients. First, as shown in LAP07 trial, radiation therapy delivered after a phase of induction chemotherapy increases local control. Second, it allows a time without treatment for patients longer than chemotherapy alone. Third, patients who receive neoadjuvant radiation therapy have a higher chance to achieve a R0 resection and a major pathological response

SP-0660 p16+ oropharyngeal cancer: new disease, new staging – what about treatment? P. Lassen 1,2 1 Aarhus University Hospital, Department Of Oncology and Experimental Clinical Oncology, Aarhus, Denmark; 2 Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada Abstract text The incidence of Human papillomavirus (HPV) associated oropharyngeal carcinoma (OPC) is increasing in developed countries, and HPV positive OPC is a distinct disease entity from HPV negative OPC characterized by a unique epidemiology, molecular biology and oncogenesis. In addition, patients with HPV positive disease tend to be younger and healthier than their HPV negative counterpart due to differences in risk profiles, especially less heavy smoking and alcohol consumption, which again results in less significant comorbidity. HPV positive squamous cell carcinoma is more sensitive to radiotherapy than HPV negative disease, and the highly significant prognostic impact of tumor HPV-status on treatment outcome and survival has led to the inclusion of HPV-associated p16 expression in the eight edition of the AJCC/UICC TNM classification system. The overall general favorable prognosis in HPV positive OPC is however heterogeneous, and it is well known, that advanced disease-stage (T3-4N2) and smoking (>10packyears) negatively impacts prognosis, which have resulted in the definition of a group of intermediate risk patients with HPV positive disease. Traditional treatment of advanced stage OPC consists of concurrent chemo-radiation, which is associated with substantial acute toxicity and long term morbidity, ultimately impacting quality of life for long-term survivors. As patients with HPV positive disease are typically younger, they will have to live longer with potential long term effects from treatment. This, combined with the general good prognosis, has led to the initiation of clinical trials investigating de-intensified therapies in HPV positive disease, in order to reduce toxicity without compromising outcome. Various strategies are presently being investigated within clinical trials including de-intensification of treatment by substituting Cisplatin with the EGFR-inhibitor Cetuximab, radiotherapy alone, reduction in adjuvant radiotherapy following primary surgery with minimally invasive surgical techniques based on pathology features and reduction in radiotherapy dose following induction chemotherapy in good responders. Given the somewhat dismal prognosis of the intermediate risk HPV positive patients, trials have been initiated focusing on optimizing outcome for this group of patients also, for instance by incorporation of concurrent immunotherapy into primary radiotherapy. The first groundbreaking results have been published regarding the substitution of Cisplatin with Cetuximab