Abstract Book

S230

ESTRO 37

rate modalities have been more and more popular in the last decades. They allow an optimisation of dose distribution by varying the dwell times over the different dwell positions. Because of the use of afterloaders, they also offer a better radioprotection of the staff. High dose rate and pulsed dose rate treatments seem to offer the same results as low-dose rate brachytherapy, particularly in cervix carcinoma. For high-dose rate brachytherapy, hypofractionated treatment schedules must be designed according to the linear-quadratic model. In pulsed dose rate brachytherapy, hyperfractionated treatment was designed in early nineties for mimicking low-dose rate brachytherapy, to replace it. Pulse dose and time intervals must also be derived from the linear-quadratic model, but half-time repair must be taken into account.

Teaching Lecture: DNA Repair: from mechanisms to clinical implication

SP-0437 DNA Repair: from mechanisms to clinical application W. Mansour 1 1 University Medical Center Hamburg - Eppendorf UKE, Lab of Radiobiology and Experimental Radiooncology, Hamburg, Germany Abstract text Genomic integrity is the fulcrum upon which cellular survival and homeostasis rest. Genomic integrity is challenged by different DNA damage types. It is estimated that each cell within the human body incurs tens of thousands of DNA-damaging events per day. DNA exclusively serves as the repository for the genetic information in each living cell and its integrity and stability are of much greater consequence than other cellular components, such as RNA and proteins. DNA damage can interfere with essential cellular processes, such as transcription or replication, and can compromise the viability of the cell. Specific DNA lesions can also induce mutations that cause cancer or other diseases as well as contribute to the aging process. Regardless of the type of lesion and the mechanism required for its repair, cells initiate a highly coordinated cascade of events - collectively known as the DNA damage response (DDR) - that senses the DNA damage, signals its presence, and mediates its repair. Moreover, DDR may transiently arrest the cell cycle to allow for efficient DNA damage repair prior to replication or mitosis or signal cells to activate apoptosis under circumstances of persistent or irreparable DNA damage. The detailed information about DNA damage types, DDR and different DNA repair mechanisms will be discussed. Induction of DNA damage is the major under- lying molecular mechanism of many anticancer regimens such as IR and several chemotherapeutic drugs. It has also been demonstrated that the ability of cancer cells to repair therapeutically induced DNA damage impacts therapeutic efficacy. This has led to targeting DNA repair pathways and proteins to develop anti-cancer agents that will increase sensitivity to traditional chemo- and/or radiotherapy. While initial studies were plagued by a lack of specificity and a defined mechanism of action, novel approaches to exploit specific DNA repair defects in tumors by employing synthetic lethality have proven considerably more effective. In this lecture, previous failures in targeting DNA repair will be discussed showing how did they pave the way for future DNA repair targeted agents and their use in cancer therapy.

ESTRO 37 Monday 23 April

Teaching Lecture: A primer on Value Based Health Care

SP-0435 A primer on Value Based Health Care A.Aggrawal London School of Hygiene and Tropical Medicine, Department of Health Services Research and Policy, London, the United Kingdom

Abstract nor received

Teaching Lecture: The systematic use of patient reported outcome measures (PROM) for the improvement of radiotherapy

SP-0436 The systematic use of patient reported outcome measures (PROM) for the improvement of radiotherapy K. Kirchheiner 1 1 Medical University Vienna, Dept. of Radiation Oncology, Vienna, Austria Abstract text Patient-reported outcome measures (PROM) describe any outcome reported directly by the patient with a subjective evaluation about disease and its treatment. PROM summarize a wide spectrum of endpoints in the framework of a holistic bio-psycho-social cancer care model, such as reports on symptoms and side effects, as well as multi-dimensional health-related quality of life, evaluation of the perceived health and psychological status, reports about adherence to treatment, satisfaction with treatment, according to the US Food and Drug Administration (FDA) and the European Medical Agency (EMA). In contrary to the physician assessed morbidity grading, the evaluation of PROM is performed without any interpretation by a clinician, relative or anyone else and reflects the patients’ subjective experience. The teaching lecture will cover the following aspects: 1. Differences between physician-assessed and patient- reported symptoms: The benefits of complementary PROM assessment 2. Comparison and discussion of two prominent PROM assessment tools: EORTC Quality of Life questionnaires and PRO-CTCAE 3. Reporting and interpretation of PROM 4. Association of PROM with clinical outcome 5. Electronic assessment of PROM

Teaching Lecture: Is stereotactic body radiotherapy an alternative to surgery in operable patients with stage I NSCLC?

SP-0438 Is stereotactic body radiotherapy an alternative to surgery in operable patients with stage I NSCLC? M. Dahele 1 1 VU University Medical Center, Radiation Oncology, Amsterdam, The Netherlands Abstract text Stereotactic body radiotherapy (SBRT) is effective, increasingly available and guideline-recommended for medically inoperable patients with peripheral early-stage non-small cell lung cancer (ES-NSCLC) However, its use in medically operable patients is