title: [Radiosensitivity settings in breast cancer].
abstract: Breast cancers are highly radiosensitive since the risk of recurrences and of mortality after adjuvant radiotherapy following breast-conserving surgery is decreased by 15.7% and 3.8%, respectively at 10 years. The total dose if irradiation also significantly increases local control: a boost of 16 Gy to the tumour bed after breast-conserving surgery reduces the absolute risk of recurrence by 4% at 10 years. Breast cancers are sensitive to the dose per fraction, as shown by the results from four randomized trials which compared standard irradiation (50 Gy/25 fractions) with a hypofractionated scheme: no statistical difference was observed in locoregional recurrence and overall survival at 10 years. The α/β ratio, which reflects the dose per fraction and is theoretically over 10 Gy for tumour tissues, has been estimated between 2.2 and 4.4 Gy for breast cancers. Molecular abnormalities, such as overexpression of HER1 (especially in triple negative breast cancer) and HER2, induce a higher radioresistance. In vitro studies showed that targeted therapies, which block these receptors, increase breast cancer radiosensitivity. Tumour stem cells have been identified in breast cancers and are characterized by a higher radioresistance. This radioresistance could be related to a better repair of radiation-induced DNA damages and a decrease of reactive oxygen species (ROS), which are involved in their occurrence. In the future, a better understanding of genetics tumour abnormalities will allow to identify new radiosensitivity settings in breast cancers.
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France. Electronic address: olivierlauche@hotmail.com.
authors.forename: O
authors.initials: O
authors.lastname: Lauche
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France; U1194, université de Montpellier, 208, rue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 05, France.
authors.forename: D
authors.initials: D
authors.lastname: Azria
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France; U1194, université de Montpellier, 208, rue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 05, France.
authors.forename: O
authors.initials: O
authors.lastname: Riou
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France.
authors.forename: M
authors.initials: M
authors.lastname: Charissoux
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France.
authors.forename: C
authors.initials: C
authors.lastname: Lemanski
authors.affiliation: Département de radiothérapie oncologique, institut du cancer de Montpellier, 208, avenue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 5, France; U1194, université de Montpellier, 208, rue des Apothicaires, parc Euromédecine, 34298 Montpellier cedex 05, France.
authors.forename: C
authors.initials: C
authors.lastname: Bourgier
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans
keywords: Breast cancer; Cancer du sein; Cellules souches tumorales; Hypofractionated and cancer stem cells; Hypofractionnement; Radiosensibilité; Radiosensitivity