Analyse des sites de récidives après chimioradiothérapie en modulation d’intensité pour le cancer du canal anal

Abstract : Aim: to evaluate patterns of failure according to irradiated volumes after chemoradiotherapy (CRT) using intensity modulated radiotherapy (IMRT) in patients treated for non metastatic anal cancers. Materials and methods: after rigid registration between the dosimetric scan and examination of the recurrence, recurrences were ranked according to the dose level of PTV1 (preventive dose) and PTV2 (additional dose): 1) “in the treated volume” (IV) if 95% or more of the recurring GTV (rGTV) was in the 95% isodose of prescription, 2) “on the edge of the volume“ (BV) if 20 % to 95 % of the rGTV was in the 95 % isodose or 3) “outside the volume” (HV) if less than 20 % of rGTV was in the 95 % isodose. Results: between 2007 and 2016, 254 patients were treated by CRT using IMRT. With a median of 27.5 months [1-103], survival without recurrence at 3 years was 76 % [69.9-81.7]. Survival without progression and local control were statistically linked to immunodeficiency (p<0.005), and to stage T3-T4 (p=0.015) using multivariate analysis. Fifty-three patients (21% ) presented distant locoregional recurrence (10 %), distant recurrence (6%), or locoregional and distant recurrence (4%) in a median period of 6 months [0 – 48]. Out of 24 dosimetric analyses of tumoral recurrence, 19 (80 %) were located in IV/ PTV2 with a D50 % median in rGTV of 60.95 Gy [44.9-69.2], 4 recurrences were in BV PTV2 and one in HV/PTV2. Of 9 pelvic lymph node recurrences, 22% were located in IV PTV2, 11% in BV PTV2 / IV PTV1, and 67 % in HV PTV2. Conclusion: our study showed that recurrences occurred in identified volumes covered by the prescribed dose. These recurrences probably show a resistance to treatment justifying intensification trials for locally advanced tumours.
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Master Thesis
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Submitted on : Tuesday, January 8, 2019 - 6:03:35 PM
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Frédéric Amestoy. Analyse des sites de récidives après chimioradiothérapie en modulation d’intensité pour le cancer du canal anal. Médecine humaine et pathologie. 2018. ⟨dumas-01974455⟩

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