Abstract book - ESTRO meets Asia

S28 ESTRO meets Asia 2018

patients affected with squamous cell carcinoma of the anus. SP-069 Vulvar cancer: technologies (EBRT, brachytherapy) and outcome D.N. Sharma 1 1 All India Institute of Medical Sciences- New Delhi- India, Radiation Oncology, New Delhi, India Abstract text Vulvar cancer (VC) is relatively a rarer gynecologic cancer; accounting for 3-5% of all malignancies of the female genital tract . It affects elderly women with the median age at diagnosis of 65 to 70 years. Prognosis is strongly correlated to inguinal lymph node metastases and the stage of disease . Treatment of VC is very challenging and complicated since treatment guidelines are largely based on retrospective and non-randomized studies. Although surgery is the main treatment, radiation therapy (RT) plays a significant role. Patients with early stage disease are often managed with surgery alone; and RT is offered as an adjuvant treatment to selected patients with adverse features. Treatment of locally advanced disease is more complicated and generally an individual approach is preferred using combination of surgery, RT or chemo- radiotherapy in order to reduce the treatment related morbidity. Use of concurrent chemo-radiotherapy (CCRT) is increasingly becoming popular mainly due to success of CCRT in cancer of cervix. RT can be used in different settings for the management of patients with VC: 1) as definitive therapy for non surgical patients, 2) as adjuvant therapy to prevent LRC, 3) as neoadjuvant therapy to improve the resectability and reduce the surgical morbidity and 4) as palliative therapy for alleviating symptoms in patients with incurable disease. Definitive RT, in the form of external beam radiation therapy (EBRT) alone or interstitial brachytherapy (IBT) alone or both, can be used in select group of patients who are not suitable for surgery. Adjuvant RT is offered to patients having adverse pathological features like close or positive surgical margins, lympho-vascular space invasion, depth of invasion >5 mm and multiple inguinal positive nodes. Usually doses of about 60-70 Gy for the gross disease and 45-50 Gy for the microscopic disease are prescribed. The specialty of RT has changed rapidly over the past two decades with introduction of computer technology and imaging. Modern, state-of-art facilities like three dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) have enabled today's patients to receive RT more accurately. Such conformal techniques have resulted in improved clinical outcome in terms of local control, survival and toxicity rates in various sites including gynecological malignancies. Treatment volumes in VC are usually large (primary site, both groins and pelvis) and therefore RT related acute and late morbidity is a serious concern. With IMRT, one can expect fewer side effects and better tolerance to CCRT regimes. There is a growing interest in IMRT for VC after the publication of consensus contouring guidelines 1 in year 2016. A recent report 2 published in 2017 has shown promising results with IMRT. Of 39 patients treated with IMRT, none showed grade 3-4 gastrointestinal or genitourinary toxicities. The 3-year loco-regional control and overall survival for those receiving definitive IMRT were 42% and 49% respectively. Technologic advances have renewed confidence in the accuracy of not only EBRT but also brachytherapy. IBT may be used alone for very early lesions and in combination with EBRT (as boost) for larger lesions. For tumors located near critical structures such as the urethra, bladder, rectum, delivery of high-dose radiation via EBRT may be difficult without exceeding dose tolerances to normal structures. Pohar et al 3 treated 34 patients with IBT alone

using a median dose of 60 Gy and reported 5-year local control and disease specific survival of 80% and 70% respectively. In a recently published report 4 , 29 patients were treated with high-dose-rate IBT consolidation after EBRT. Results were found to be very favorable with 5-year local control rate of 77% and disease-free survival of 51%. In conclusion, CCRT is slowly becoming a popular option both as preoperative and definitive treatment. Due to vulvar anatomy and proximity of critical organs, conformal RT technique like IMRT is quickly becoming a standard radiotherapeutic option for vulvar cancer. References 1. 1. Gaffney DK, King B, Viswanathan AK, et al. Consensus recommendations for radiation therapy contouring and treatment of vulvar carcinoma. Int J Radiat Oncol Biol Phys 2016; 95: 1191-1200. 2. 2. Rao YJ, Chundury A, Schwarz JK, et al. Intensity modulated radiation therapy for squamous cell carcinoma of the vulva: treatment technique and outcomes. Advances in Radiat Oncol 2017; 2; 148-158. 3. 3. Pohar S, Hoffstetter S, Peiffert D, et al. Effectiveness of brachytherapy in treating carcinoma of the vulva. Int J Radiat Oncol Biol Phys 1995; 32: 1455-1460. 4. 4. Mahantshetty U, Naga P, Engineer R, et al. Clinical outcome of high dose rate interstitial brachytherapy in vulvar cancer: a single institutional experience. Brachytherapy 2017; 16: 153-160.

Teaching lecture: Oxygen effect, sensitizers, microenvironment SP-070 Oxygen effect, sensitizers, microenvironment A. Van der Kogel University of Wisconsin, Wisconsin, USA

Abstract not received

Teaching lecture Oxygen effect, sensitizers, microenvironment

SP-071 Personalised delineation in rectal cancer P. Franco 1 1 University of Turin, Department of Oncology- Radiation Oncology, Turin, Italy Abstract text A multidisciplinary approach is presently considered the standard of care for the treatment of locally advanced rectal cancer. Pre-operative RT is a well-established option to provide tumor downsizing and downstaging and to increase loco-regional control in this setting. Selection and delineation of clinical target volumes and organs at risk are crucial steps to deliver precise and tailored radiation. While the sites and subsites of irradiation are, to some extent, agreed by physicians, the boundaries of CTVs still remain controversial, leading to inhomogeneous contours and systematic errors with standard deviations as high as 1 cm, as reported in different studies. Most of the heterogeneity is due to the difference in contouring protocols used by the treating physician, but the magnitude of this uncertainty is also related to the imaging modalities and technical employed. In the context of pelvic malignancies, one of the major sources of uncertainty is the lack of clearly-defined anatomical boundaries in this region, which may lead to detectable contouring differences among radiation oncologists. From an anatomical point of view, the site of major disagreement is to be located in the upper anterior and inferior aspect of the mesorectum, which is a critical structure for tumor control given the likelihood of microscopic involvement, particularly for locally advanced cases. Several strategies can be implemented to