Abstract Book

S353

ESTRO 37

(kV) imaging, there is a limit to what can be achieved. Employing the most appropriate tracking methodology to match the site to be treated is the first step. All intra- cranial sites are tracked using the skull as a surrogate, and extra-cranial sites close to or in a vertebral body are tracked on a short section of the spine. As each pair of kV images taken on-set is analysed the resulting residual displacement is corrected for in 6DOF by the robot at the next node (point in space) and beam delivery. These orthogonal image pairs are at a fixed position in the treatment room at 45 0 to the patient. Image analysis is almost instantaneous, but as Cone-Beam Computed Tomography (CBCT) is not available yet in-room, there is no three dimensional (3D) volumetric information. For soft tissues sites, and bony sites distant from the spine, fiducial marker tracking is used. To achieve rotational corrections a minimum of 3 markers must be inserted fulfilling strict geometrical criteria. A sub-optimal marker insertion or migration following the insertion may by necessity lead to rotations being disabled, thus reducing the accuracy of treatment delivery and leading to some uncertainty in dosimetry. Planning Target Volumes (PTV) margins can be modified up-front with this information in mind. Poor positioning and/or reproducibility of the patient can also lead to difficulties tracking e.g. unable to hold their arms up, very lateralised target with beams entering from the contra-lateral side, patients with a large Body Mass Index (BMI), erratic respiration patterns, or excessive respiration motion causing extremes of rotation. This presentation will discuss the challenges mentioned and suggest strategies to achieve the most optimal dosimetry and the most optimal patient position. SP-0668 Integrated care for older radiotherapy patients A. O'Donovan 1 1 Trinity Centre for Health Sciences St James Hospital, Discipline of Radiation Therapy, Dublin, Ireland Abstract text Radiation therapy is a cancer modality that can be an excellent option for older patients due to its limited systemic toxicities, especially where surgery and chemotherapy are deemed unsuitable. Approximately 50- 60% percent of all cancer patients receiving treatment will require radiotherapy at some stage of their treatment trajectory, and the majority of these will be older patients. Most European countries are currently faced with a major demographic shift that will see increasing numbers of older patients. This represents a corresponding increase in the number of older patients presenting for radiation therapy. It is recognised that this will require “age attuning” of our cancer treatment services to provide more integrated care for these patients. Traditionally the disciplines of Oncology and Geriatric Medicine have worked independently of each other in many countries. This is beginning to change, as it’s recognised that most older patients have complex medical profiles, and that information provided by the specialised discipline of Geriatric Medicine may help treatment decisions and rehabilitation of older cancer patients, providing a more holistic care option. Comprehensive Geriatric Assessment (CGA) or Geriatric Assessment (GA) as used in the oncology literature, can identify risk factors for adverse outcomes in older cancer patients. CGA was designed to more accurately detect frailty in older patients, and both the National Symposium: Implications of the ageing population for radiation oncology

Comprehensive Cancer Network (NCCN) and International Society of Geriatric Oncology (SIOG) recommend its use in Oncology. CGA includes a compilation of reliable and valid tools to assess geriatric domains such as comorbidity, functional status, physical performance, cognitive status, psychological status, nutritional status, medication review, and social support. The aim of this presentation is to present a critical overview of the current literature on GA in radiation oncology, and previous research by the authors in this field. It will also incorporate aspects of feasibility and requirements for a geriatric oncology service. The latter will include educational aspects and the need for adapted curricula in radiation oncology to incorporate aspects of aging, optimal treatment and attitudes towards aging. SP-0669 Clinical perspective I. Kunkler 1 1 Western General Hospital- Edinburgh Cancer Centre, Clinical Oncology, Edinburgh, United Kingdom Abstract text Implications of the ageing population for radiation oncology: clinical perspective Professor Ian Kunkler Despite the rising incidence in the older age group, the evidence base for elderly specific radiation treatment strategies remains weak with a dearth of level 1 evidence. Greater longevity, associated with multiple comorbidities, and impaired treatment tolerance have to be taken into account while maximizing cure rates and quality of life (QoL) and minimizing toxicity. Advanced techniques eg intensity-modulated radiation therapy and precision tools (genomics, radiomics and mathematical modelling) offer possibilities of personalised, adaptive radiotherapy (1). Genomic signatures may, if validated, identify patients likely to benefit from RT (2) Older patients with a variety of solid tumours may benefit from primary, adjuvant or palliative radiotherapy (RT). Recommendations for RT were drawn up by the International Geriatric Oncology Society (SIOG) (3) and by Pfeffer & Blumenfeld (4). Hypofractionated treatment schedules are more convenient for older patients. Nearly half of non small cell lung cancer (NSCLC) occurs in patients =/> 70 years. Stereotactic body RT (SBRT) provides about 90% short term local control for medically inoperable stage I NSCLC and 79% 5 year local control (5,6). SBRT is feasible both for peripheral and central lung tumours (7, 8) as well as tumours >5cm diameter. In patients =/>70 years 30 day mortality was lower with SBRT (1.7%) compared to surgery (8.3%) but with similar 1 and 3 year survival rates (9). The omission of postoperative whole breast RT (WBRT) after breast conserving surgery in older patients with early breast cancer remains controversial and guidelines vary. The PRIME 2 trial showed a modest but statistically significant reduction in local control (local recurrence 4.1% RT- vs 1.3% RT+) at 5 years from the omission of WBRT in patients =/> 65 years with T1-2 (up to 3cm),pNO, hormone receptor positive tumours (10). The CALGB 9343 (11) in a lower risk group (T1, NO, ER positive) treated with tamoxifen showed WBRT reduced the risk of local recurrence by 7% at 10 years (2% vs 9%). Of head and neck (HN) cancer patients, 25% are aged > 70 years. Better overall survival and loco-regional control is achieved with hyperfractionated RT in RCTs and metanalyses. In a large retrospective study of HN patients undergoing radical RT (12), 238 patients =/> 75 years showed no difference in therapy related mortality, interruption in treatment or completion rates. However 2 year cause specific survival was lower in elderly patients. An analysis of 1589 patients in 5 EORTC trials showed that increasing age did not compromise overall survival (13).The ability of intensive modulated radiotherapy to reduce toxicity has been confirmed in a study comparing