OC-0345: Patterns of failure after radiotherapy in pediatric ependymoma: correlation with dose parameters
Bildiriler > Özet Bildiri
Yazarlar: F. Tensaouti, A. Ducassou, S. Bolle, X. Muracciole, B. Coche-dequeant, L. Claude, S. Supiot, C. Alapetite, V. Bernier, A. Huchet, C. Kerr, E. Le Prise, G. Truc, E. Regnier, S. Chapet, A. Lisbona, G. Hangard, A. Laprie
Radiotherapy and Oncology, , , Uluslararası, Özet Bildiri, cilt 119, ss S158-S159
DOI: 10.1016/s0167-8140(16)31594-8
Özet
Purpose or Objective: The majority of intraprostatic recurrences after radical prostate radiotherapy occur at the site of initial tumour, in previous reported series.However, there is no published data directly comparing recurrence patterns after different modalities of radiotherapy.The aim of this study was to investigate differences in spatial pattern of intra-prostatic recurrences on multiparametric MRI, after external beam radiotherapy or brachytherapy. Material and Methods:We identified 382 consecutive patients referred for multiparametric MRI after previous prostate cancer treatment.Patients with post-radiotherapy biochemical recurrence and intraprostatic recurrence on MRI were included in the study.Scans were independently reviewed by two radiologists.The location of recurrence was mapped to prostate sectors based on European consensus guidelines.The chi-square test was used to analyse differences in site of recurrence between modalities of radiotherapy.Results: 66 patients who had radical radiotherapy between 1997 and 2013 had intraprostatic recurrence on MRI.The D'Amico risk stratification at initial diagnosis was 14% lowrisk, 34% intermediate-risk and 52% high-risk.The series consisted of 34 patients after external beam radiotherapy (EBRT), 20 patients after low-dose rate brachytherapy (LDR) and 12 after high-dose rate brachytherapy monotherapy (HDR mono).68% of the EBRT recurrences had received a dosefractionation schedule with an EQD2 less than 74 Gy.The mean time between the end of radiotherapy and imaging recurrence was 77 months (95% CI 68 -85 months) with no significant differences between treatment groups.80% of patients did not have any associated pelvic bony metastasis or nodal disease.88% of patients had a contiguous intraprostatic recurrence.The median recurrence size detected on MRI was 2.0 cm (range 0.6 -4.2 cm).Recurrences after EBRT were more likely to involve multiple sectors of the prostate.71% of EBRT recurrences involved the apex compared to 30% after LDR and 25% after HDR mono (p = 0.003).In the LDR group, recurrences involved the base of the gland in 60% of cases, compared to 41% after EBRT and 8% after HDR mono (p = 0.016).21% of patients underwent salvage treatment with cryotherapy, HDR brachytherapy or prostatectomy.Conclusion: Apical recurrences predominated in patients following EBRT.This highlights the need for MR-fusion during EBRT target definition because the apex is difficult to visualise on CT.Basal recurrences were associated with LDR brachytherapy, which may reflect a tendency of radioactive seed migration away from the base.The use of multiparametric MRI facilitates identification of patients for focal salvage treatment.