Abstract Book

S201

ESTRO 37

series treated with RT + conventional BT without chemotherapy (Washington, 1499 patients; French cooperative study, 1875 patients) and the Vale meta- analysis of 13 randomised trials of chemo-RT + conventional BT (3128 patients). Results Figure 1 shows the number of patients with different types of failure. The total number of failures (single and synchronous) during the observation period was 325. 9% of patients had local failure, 6% regional failure and 13% pelvic failure. 24% of patients had distant failure; of these, 9% had PAN failure and 21% had systemic failure. 24% of the patients with PAN failure had PAN RT (i.e. in- field recurrence) while in the remaining 76%, recurrence was outside the irradiated field.

Conclusion Adherence to the EMBRACE II protocol improved inter- institutional consistency, decreased irradiated volumes and improved conformality considerably. By application of joint contouring guidelines, IMRT and daily IGRT, V43Gy was reduced by >950cm 3 for pelvic and PAN patients. These encouraging results need to be confirmed through future patient accrual. The overall decrease in irradiated volumes is expected to lower the incidence and intensity of EBRT related complications. OC-0392 Impact of image-guided brachyther apy on pattern of relapse in the RetroEMBRACE cervical cancer study L.T. Tan 1 , K. Kirchheiner 2 , A. Sturdza 2 , L. Fokdal 3 , C. Haie-Meder 4 , P. Hoskin 5 , I.M. Jürgenliemk-Schulz 6 , J. Lindegaard 3 , C. Kirisits 2 , K. Tanderup 3 , R. Pötter 2 1 Cambridge University Hospitals, Oncology Centre, Cambridge, United Kingdom 2 Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria 3 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark 4 Institut Gustave Roussy, Department of Radiation Oncology, Villejuif, France 5 Mount Vernon Cancer Centre, Department of Oncology, Northwood, United Kingdom 6 University Medical Center Utrecht, Department of Radiation Oncology, Utrecht, The Netherlands Purpose or Objective The RetroEMBRACE study has previously shown that IGBT for cervical cancer improves pelvic control to 87% and overall survival by ~10%. This present analysis investigates the impact of IGBT on patterns of failure. Material and Methods Data from 731 patients treated in 12 institutions were analysed. All patients received initial EBRT - 84% to the pelvis alone and 16% to the pelvis and paraaortic nodes (PAN). 77% patients received concomitant chemotherapy. MRI-based IGBT was used in at least one application in 81% of patients, and CT alone in 19%. In 23% of patients, combined intracavitary/interstitial BT was used in at least one fraction. Treatment failures were classified as local (cervix, upper vagina and/or parametria), regional (pelvic nodes), pelvic (local and/or regional), systemic (excluding PAN relapse) or distant (including PAN relapse). The pattern of failure at time of first relapse was analysed and compared with two large published

A comparison of patterns of failures in the Washington, French, Vale and RetroEMBRACE series is shown in Figure 2. Overall, 30% of the RetroEMBRACE cohort experienced treatment failure compared to 35% in the Vale chemo-RT series and 38% and 39% in the Washington and French RT alone series. 36% and 33% of the Washington and French cohorts had synchronous pelvic and distant failure compared to 22% and 23% of the Vale and RetroEMBRACE cohorts. In the Vale chemo-RT series, the predominant form of failure was in the pelvis alone. In the RetroEMBRACE IGBT series, distant-alone relapse was the predominant form of failure.

Conclusion Our analysis has shown an interesting shift in patterns of recurrence with evolving treatment. In the RT alone era, both loco-regional and distant control were problematic except for patients with early-stage disease with a low propensity for metastatic spread. The addition of concomitant chemotherapy improved survival for early- stage patients but advanced-stage patients continued to succumb to uncontrolled pelvic disease. The implementation of IGBT has resulted in distant failure being the predominant problem. Improved methods to identify patients with high individual risk of different types of failure are needed to facilitate personalisation of treatment strategies.