[Clinical to target volume margins determination in radiotherapy for anal cancers].
There are very few data on the expansion from the clinical target volume (CTV) to the planning target volume (PTV) in the anal cancer treatment. This article aims to collect the different elements needed for the construction of a PTV from scientific data based on a literature analysis. We reviewed the articles published in the medical literature from the last 20years. They concerned setup errors and internal organ mobility of the different volumes of patients treated by conformational radiotherapy and intensity-modulated radiotherapy (anal canal, meso-rectum, common, intern and extern, inguinal and pre-sacral lymph nodes). CTV to PTV margins admitted in the guidelines and atlas of consensus groups (SFRO, RTOG, AGITG) are from 0.7 to 1cm in all directions, based on expert's opinions but not on scientific data. There are no specific studies on the canal anal mobility. Most of the data are from other pelvis cancers (gynecologic, rectum and prostate). Setup errors can be reduced by daily imaging. Patient repositioning and immobilization modalities are mostly local habits rather than scientific consensus. A three-dimensional 1cm margin is generally admitted. Margins reduction must be careful and has to be assessed.
Service de radiothérapie, institut de cancérologie de l'Ouest-Nantes, boulevard Jacques-Monod, 44800 Saint-Herblain, France. Electronic address: vincent.libois@gmail.com.
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V
Libois
Service de radiothérapie, institut de cancérologie de l'Ouest-Nantes, boulevard Jacques-Monod, 44800 Saint-Herblain, France.
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MA
Mahé
Service de radiothérapie, institut de cancérologie de l'Ouest-Nantes, boulevard Jacques-Monod, 44800 Saint-Herblain, France.
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E
Rio
Service de radiothérapie, centre Georges-François-Leclerc, 1, rue du Pr-Marion, 21079 Dijon, France.
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Maingon
D001005:Anus Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007422:Intestines / Q000502:physiology; D009068:Movement / Q000502:physiology; D056888:Patient Positioning; D061106:Radiotherapy Setup Errors / Q000517:prevention & control; D061089:Radiotherapy, Image-Guided; D050397:Radiotherapy, Intensity-Modulated
Anal cancer; Cancer anal; Image-guided radiotherapy; Intensity-modulated radiotherapy; Marge du volume cible prévisionnel; PTV margin; Radiothérapie conformationnelle avec modulation d’intensité; Radiothérapie guidée par l’image