title: From technological advances to biological understanding: The main steps toward high-precision RT in breast cancer.
abstract: Radiotherapy improves local control in breast cancer (BC) patients which increases overall survival in the long term. Improvements in treatment planning and delivery and a greater understanding of BC behaviour have laid the groundwork for high-precision radiotherapy, which is bound to further improve the therapeutic index. Precise identification of target volumes, better coverage and dose homogeneity have had a positive impact on toxicity and local control. The conformity of treatment dose due to three-dimensional radiotherapy and new techniques such as intensity modulated radiotherapy makes it possible to spare surrounding normal tissue. The widespread use of dose-volume constraints and histograms have increased awareness of toxicity. Real time image guidance has improved geometric precision and accuracy, together with the implementation of quality assurance programs. Advances in the precision of radiotherapy is also based on the choice of the appropriate fractionation and approach. Adaptive radiotherapy is not only a technical concept, but is also a biological concept based on the knowledge that different types of BC have distinctive patterns of locoregional spread. A greater understanding of cancer biology helps in choosing the treatment best suited to a particular situation. Biomarkers predictive of response play a crucial role. The combination of radiotherapy with molecular targeted therapies may enhance radiosensitivity, thus increasing the cytotoxic effects and improving treatment response. The appropriateness of an alternative fractionation, partial breast irradiation, dose escalating/de-escalating approaches, the extent of nodal irradiation have been examined for all the BC subtypes. The broadened concept of adaptive radiotherapy is vital to high-precision treatments.
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy. Electronic address: cristina.leonardi@ieo.it.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Leonardi
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy.
authors.forename: Rosalinda
authors.initials: R
authors.lastname: Ricotti
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy.
authors.forename: Samantha
authors.initials: S
authors.lastname: Dicuonzo
authors.affiliation: Medical Physics Unit, European Institute of Oncology, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Cattani
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Morra
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Dell'Acqua
authors.affiliation: Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy; Scientific Directorate, European Institute of Oncology, Milan, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Orecchia
authors.affiliation: Radiotherapy Division, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy.
authors.forename: Barbara Alicja
authors.initials: BA
authors.lastname: Jereczek-Fossa
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D058990:Molecular Targeted Therapy; D057285:Precision Medicine / Q000379:methods / Q000639:trends*; D011829:Radiation Dosage; D011878:Radiotherapy / Q000379:methods / Q000639:trends
keywords: Adaptive radiotherapy; Breast cancer; High-precision radiotherapy; Technological advances; Tumor biology