ESTRO 36 Abstract Book

S206 ESTRO 36 2017 _______________________________________________________________________________________________

Main hypothesis (at end of problem definition) Objective - has to be very clear and must refer to the study population Research question VERY IMPORTANT! - it must be crystal clear and simple, end with a question mark. From a good research question you can derive the methods. Specific aims (not too much sub questions, they make the proposal less clear!) Preliminary data - The preliminary data should support your hypothesis Workplan - Develop a separate work plan for each aim. Don’t spend too much space on detailed methodology. The question to think about when developing the workplan is - “What experiments do I need to do to accomplish the specific aim?”. The experiments should always try to answer questions and not be just about data collection. This is the idea behind ‘hypothesis driven research’. The hypothesis is tested by conducting smart experiments. The work plan should use modern and elegant techniques, but must also be feasible. Try to convince the reviewer that you can do it. Convince the reviewer you will have access to the data. Statistic : work out the sample size and the validation Budget – it must be realistic. Often you need real offers from HR and external parties. Step 3: Plan a second discussion with experts in the area Step 4: fill the gaps, do a series of proofreading on the electronic and the paper version and submit it. Adenocarcinoma of the rectum is a heterogeneous disease. Surgery and radiotherapy (RT) both serve as a primary modality to achieve local control, and each as a single modality can be curative, but surgery with total mesorectal excision (TME) is the mainstay of treatment and a multimodality approach has usually been considered more effective in locally advanced rectal cancer (LARC). Historically the high loco-regional recurrence rate after radical surgery alone, which was a challenge to salvage and resulted in symptoms, which are difficult to palliate, has dominated decision-making. Metastatic disease is now the commonest mode of recurrence and cause of death, and hence currently the focus of treatment is the reduction of metastatic disease. For patients who are either medically unfit or refuse the operation, radiotherapy alone or chemoradiotherapy is frequently recommended as an alternative option, but rarely leads to cure unless early stage. Around 15% of patients with LARC achieve a complete response after CRT with 20-30% having a minimal response. However, in the event of a complete clinical response many now advocate a non-operative ‘watch-and-wait’ strategy. From the oncological point of view there a several potentially appropriate options including surgery alone, neoadjuvant chemotherapy, short course preoperative radiotherapy (SCPRT) with a long or short interval to surgery, chemoradiotherapy (CRT) and combinations of the above. Preoperative radiotherapy reduces local recurrence, but does not impact on overall survival. This reduction in local recurrence comes at a price. The increasing focus on the quality of life leads us to recognize that, in return for gains in local control for a few, many patients suffer long-term adverse consequences of surgery and RT. Symptoms such as chronic pain, faecal incontinence, and sexual difficulties are reported in both sexes. The ‘low anterior resection syndrome’ (LARS) or LARS is frequently reported by Symposium: Rectal cancer – prediction and individualisation SP-0387 Sequence of radiotherapy, chemotherapy, and surgery: current concepts and trials R. Glynne-Jones 1 1 Mount Vernon Hospital, Northwood Middlesex, United Kingdom

patients and enhanced by the addition of SCPRT/CRT. The gains in function achieved by a long rectal remnant are lost if radiotherapy is added. For this reason trials have been developed, which omit radiotherapy if a good response to chemotherapy is observed Appropriate selection is the key to the best results. Individualization requires an effective MDT, which takes account of current guidelines, but selects the optimal treatment according to good quality MRI, surgery and pathology. The decisions should reflect the staging and clinical features and molecular biology of the tumour, and also the wishes and preferences of the patient. The MDT should audit its results regularly to move with developments in technology and re-evaluate its decision-making. From all of the above, it is clear that the ability to predict tumor response before and after each of these possible strategies would be useful to tailor the use and intensity of neoadjuvant treatment 1 Netherlands Cancer Institute Antoni van Leeuwenhoek H ospital, The Netherlands Cancer Institute, Amsterdam, The Netherlands The basis of the current treatment of rectal cancer is a radical total mesorectal excision (TME), and while this provides superior oncological control, it is associated with morbidity and functional problems. Broadly there are three types of organ preservation approaches: 1. transanal local excision of a very early tumors, in which the mesorectum is left untreated because the risk of lymph node metastases is very low or non-existent 2. transanal local excision of early tumors with added (neo)adjuvant radiotherapy to eradicate potential small mesorectal lymph node metastases 3. upfront ChRT for mostly larger tumors, with omission of TME surgery only when reassessment shows a clinical complete response All organ preservation approaches inherently accept a higher incidence of residual disease in the bowel wall or lymph nodes and rely on active surveillance to detect and treat residual disease when still amenable to salvage TME. The real oncological risk of organ preservation is that some of the regrowths could not be easily amenable to salvage surgery and that some could be the source of metastases. Although the available series suggest that with adequate selection and follow up this risk is very small, the exact risk is not yet well established. Assessment of response The most commonly used restaging modalities to assess a complete response in the bowel wall and the lymph nodes are rectal examination, flexible sigmoidoscopy and MRI, including diffusion weighted imaging (DWI). The difficulty for T2w MIR, as with all imaging methods, is to distinguish fibrotic thickening from viable tumor cells. Adding DWI improves the accuracy but the still is a tendency overestimate the presence of residual tumor. For the lymph nodes T2w MRI is currently the best imaging method, with a reasonable accuracy, better than in primary staging. The luminal component of the tumor is very well assessed with endoscopy and digital rectal examination (DRE. A typical complete response presents as a white scar in the rectal mucosa, with or without telangiectasia and no palpable lesions. However, the endoscopic findings are sometimes less clear with small residual flat ulcers, some residual redness of the mucosa, and with subtle soft lesions on DRE. Half of these “near complete responses” actual complete responders in the healing phase of the bowel wall. Biopsies have a limited value due to sampling errors. A local excision of the remaining scar could provide histological proof, however with disadvantage of a higher complication rate than in non-irradiated patients, with sometimes a painful slow SP-0388 Organ preservation by optimised radiotherapy: ready for prime time? G. Beets 1