significantly worse than grade III, with an instantaneous hazard ofdeath 3.7 times higher (P¼ 0.0001).Conclusions: Patients with histological grade III/radiological GBMhave an outcome equivalent to GBM. This demonstrates the valueof combining imaging with pathology in a multidisciplinary setting,and radiological appearances should be considered in reaching thefinal diagnosis. With our current state of knowledge, and thebackground of dismal prognosis for HGG, patients with grade III/IVtumours should be managed as glioblastoma. They should thereforebe eligible for temozolomide chemotherapy.

31 A Forward-planning Solution for the IMPORT HIGH BreastIMRT Trial

L. Conway*y, Y. Tsang*yon behalf of the IMPORT Trial Management Group*Mount Vernon Hospital, Middlesex, UK; yNational ClinicalTrials Quality Assurance Group

Aim: To investigate the feasibility of a forward-planned solution toachieve the planning goals in the IMPORT HIGH trial protocol. Thistrial tests concomitant versus sequential boost using IMRT afterconservation surgery for women with higher than average localrecurrence risk from early breast cancer. The protocol states thatplans in the test arm should allow dose escalation to the tumourbed (either 48 or 53 Gy) without significantly increasing dose tocritical structures.Methods: IMRT planning was carried out on 10 post-operativebreast patients with a seroma clearly visible on CT (Pinnacle v6.2).The tumour cavity was defined by the visible seroma, outlined bya clinician and grown to generate a CTV (CTVTB) and partial breastPTV (PTVPB). The forward-planning technique comprised tangentialopposed beams to the whole breast, mini-tangent fields to thequadrant containing the tumour bed, and non-coplanar fields tothe boost volume. A coplanar technique can also be considered forthe boost.Results: 9 out of 10 plans met the required V95 criteria for CTVTB of95%. V20efor the ipsilateral lung was less than 10% for all plans. Forall test plans there was no significant difference between lung V20

for IMPORT HIGH plans and conventional whole breast tangentsd the maximum increase for IMPORT HIGH was 0.4%. For left-sidedtumours Ve5 for the heart was less than 2% for all plans. Themaximum increase was 0.2% compared with whole breast tangentsd this was deemed not clinically significant.Conclusion: Good protocol compliance has been demonstrated andthe technique incurs no clinically significant increase in dose to theorgans at risk. Set-up time and complexity are potentiallyincreased compared with an inverse planning method, howeverthe method is achievable for centres with no access to inverseplanning or IMRT facilities.

32 The Impact of Dose Escalated Radiotherapy for ProstateCancer

J. Staffurth, M. MasonResearch Departments, Velindre Hospital, Whitchurch,Cardiff, UK

Introduction: Four randomised trials have shown that doseescalated prostate radiotherapy (DEPRT) improves tumour relatedoutcomes, using additional fractions (3 photons, 1 proton) todeliver the boost (additional dose 11e15.6%). Two of the threetrials performing a subgroup analysis did not show an advantage intheir low-risk group patients. The aim of this study was to estimatethe additional number of fractions required to implement DEPRTlocally.Method: Our electronic patient record (ISCO) was used toidentify patients starting prostate radiotherapy between 01/01/2006 and 30/06/2006. The impact of selecting patients for DEPRTusing various criteria (all patients; non low-risk; !70 years; ! 70years and non low-risk) was modelled assuming DEPRT delivery in37#.

Results: 158 patients were identified, of whom 7 received post-operative radiotherapy and 33 received prostate and pelvicradiotherapy. Of the remaining 118 patients, 73 (62%) were !70years, 45 (82%) R 70 years and 10 (8%) R 75 years. 19% were low-risk: 26% of the !70 years, 9% R 70 years and 0% R 75 years. 80%were treated in 20# and 20% in 37#: 2761# were used to treat thesepatients.DEPRT for all patients; non-low risk; !70 years and !70 years andnon low-risk would require 4366#, 3992#, 3601# and 3278#respectively (an increase of 3210#, 2462#, 1680# and 1034# perannum). We would require 13e40% of an additional linac, assuming8000 #/linac/year. Using advanced techniques (IMRT or IGRT) wouldallow delivery of DEPRT to all patients and freeing of 800# perannum, assuming equivalent overall delivery time.Conclusion: DEPRT improves biochemical control and as yet we areunaware of any patient group that does not benefit. IntroducingDEPRT can have significant radiotherapy delivery resource impli-cations. Patient selection using risk stratification and age ispossible, although ethical issues should be considered. Advancedradiotherapy techniques may have a role in limiting the re-quirement for additional linear accelerators. Planning issues havenot been studied.

33 Radiosensitivity, Radiogenomics & RAPPERR. M. Elliott*, N. G. Burnety, A. M. Dunningz, D. P. Dearnaleyx,C. E. Colesy, C. M. L. West**Academic Radiation Oncology, Division of Cancer Studies, TheUniversity of Manchester, Christie Hospital, Manchester, UK;yUniversity of Cambridge, Department of Oncology, OncologyCentre, Addenbrooke’s Hospital, Hills Road, Cambridge, UK;zCRC Human Cancer Genetics Group, Strangeways ResearchLaboratory, Cambridge, UK; xAcademic Unit of Radiotherapyand Oncology, Royal Marsden Hospital NHS Foundation Trustand The Institute of Cancer Research, Surrey, UK

Variation exists between individuals in the severity of their normaltissue response to radiotherapy. Although clinical (e.g. smoking,co-morbid conditions) and physical (e.g. radiation dose, volume)factors are important, there is strong evidence that genetics playsa crucial role in determining the likelihood of developing toxicity.Individual radiosensitivity is considered to be an inherited complextrait dependent on interactions between multiple genes/geneproducts. High-throughput genotyping provides opportunities toexamine underlying determinants of individual variation in radio-sensitivity.The RAPPER study is designed to explore associations betweensingle nucleotide polymorphisms (SNPs) in candidate genes andradiation toxicity. It is a multi-centre study with planned re-cruitment of 2200 patients from large national and single-centreradiotherapy trials. Allowing for a 10% loss, RAPPER is powered todetect common alleles conferring a moderate risk of late morbidity(relative risk¼ 1.5), as well as rarer ones with larger effects.Breast, prostate or gynaecological cancer patients are beingrecruited to increase heterogeneity and identify polymorphismsaffecting radiation response across tumour types. EDTA bloodsamples have been collected from 1075 patients (w50% of target),with surplus stored for future collaborations. CTCAE (incorporatingLENT-SOMA) and quality-of-life questionnaires are regularly com-pleted to score toxicity.Rapid developments in high-throughput genotyping may allowstudy of 120 genes using SNP-tags to cover all common variation ineach gene. Selection of the candidate list will be finalised in w2years but will focus on cell cycle checkpoint control, DNA damageresponse and cytokine pathways. Whole genome analysis iscurrently considered to be beyond the scope of RAPPER. However,we will make a substantial contribution to the pan-Europeaninitiative GENEPI, which aims to make available samples andclinical data required for future genotyping validation projects.Identifying a link between genotype and radiosensitivity could leadto the development of genetic profiles for the future individualisa-tion of radiotherapy.

S15CLINICAL ONCOLOGY