Critical appraisal of the role of volumetric modulated arc therapy in the radiation therapy management of breast cancer

Cozzi et al. Radiation Oncology (2017) 12:200 DOI 10.1186/s13014-017-0935-4 REVIEW Open Access Critical appraisal of the role of volumetric modulated arc therapy in the radiation therapy management of breast cancer Luca Cozzi1,2* , Frank Lohr3, Antonella Fogliata1, Davide Franceschini1, Fiorenza De Rose1, A R Filippi6, Gabriele Guidi5, Valentina Vanoni4 and Marta Scorsetti1,2 Abstract Background: The aim of this review is the critical appraisal of the current use of volumetric modulated arc therapy for the radiation therapy management of breast cancer. Both clinical and treatment planning studies were investigated. Material and methods: A Pubmed/MEDLINE search of the National Library of Medicine was performed to identify VMAT and breast related articles. After a first order rejection of the irrelevant findings, the remaining articles were grouped according to two main categories: clinical vs. planning studies and to some sub-categories (pointing to significant technical features). Main areas of application, dosimetric and clinical findings as well as areas of innovations were defined. Results: A total of 131 articles were identified and of these, 67 passed a first order selection. Six studies reported clinical results while 61 treatment dealed with treatment planning investigations. Among the innovation lines, the use of high intensity photon beams (flattening filter free), altered fractionation schemes (simultaneous integrated boost, accelerated partial breast irradiation, single fraction), prone positioning and modification of standard VMAT (use of dynamic trajectories or hybrid VMAT methods) resulted among the main relevant fields of interest. Approximately 10% of the publications reported upon respiratory gating in conjunction with VMAT. Conclusions: The role of VMAT in the radiation treatment of breast cancer seems to be consolidated in the in-silico arena while still limited evidence and only one phase II trial appeared in literature from the clinical viewpoint. More clinical reports are needed to fully proove the expected dosimetric benefits demonstrated in the planning investigations. Keywords: Volumetric modulated arc therapy, Breast cancer, Radiotherapy Background The introduction of volumetric modulated arc therapy (VMAT) in clinical practice dates back to 2008 after the publication of the seminal work of Otto [1] which opened the road to the implementation of VMAT optimisation algorithms in the treatment planning systems. Since then, VMAT has been applied to almost all possible clinical indications and a huge amount of research was published. The navigation through this * Correspondence: 1 Radiotherapy and Radiosurgery Department, Humanitas Research Hospital, Via Manzoni 56, 20089 Rozzano-Milan, Italy 2 Department of Biomedical Sciences, Humanitas University, Rozzano, Italy Full list of author information is available at the end of the article plethora of articles is challenging and for this reason, the availability of site-specific reviews might help to appraise the state of the art and the role of VMAT in the management of the radiation oncology process. Breast cancer is one of the most common diseases and its incidence is increasing and will continue to increase due to early diagnosis programs as well as to the demographic effect. Radiotherapy is a fundamental component of the multidisciplinary approach to breast cancer and, depending on several factors, many different fractionation schemes and treatment modalities have been applied and explored with success. The clinical use of VMAT for breast cancer is still limited, according to published data, but it is potentially a versatile solution, applicable to whole breast or partial © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Cozzi et al. Radiation Oncology (2017) 12:200 breast treatments, conventional or altered fractionation schemes (sequential or with simultantous integrated boost, hypofractionated and even in single fraction). Also from the technological point of view, interesting variants of VMAT have been proposed and tested in-silico to explore future possibilities. A number of earlier published reviews [2–10] addressed some early technical aspects of VMAT or covered the role of VMAT in general or in other districts (lung, head and neck, brain or SBRT). Fiorentino [6] proposed a case review of a bilateral breast irradiation with a limited review of literature, mostly focused on tomotherapy practice. Aim of this review is to summarize the clinical evidence from literature and provide an overview of the main technical aspects and of the ongoing research activities to consolidate the knowledge about the role of VMAT for breast cancer treatment. Materials and methods Search and selection criteria The database of the National Library of Medicine was searched through the Pubmed/MEDLINE service. The time search was limited to articles published after January 2008 when the article of Otto [1] was published. The following keys were searched in all field of the article record: “breast” and any of the following: “volumetric modulated arc therapy”, “VMAT”, “RapidArc”, “Rapid Arc”, “hybrid IMRT” or “hybrid-IMRT” or “hybrid intensity modulated radiotherapy”. The resulting set of references was further pruned after full text examination to exclude irrelevant articles errononeously associated to the selection criteria, duplicate records or reviews. The time selection was set to the publication of the original article describing the modern concept of VMAT. This intentionally excluded the predecessors like intensity modulated arc therapy (IMAT) and all its variants. Similarly, the literature search exluced from the primary keys the use of Helical Tomotherapy or of its derived TomoDirect (TD) approach specific to breast since the review scope was to discuss the linac-based use of VMAT. Some Tomotherapy related articles remained after the selection being relative to treatment planning comparisons among different techniques. The rational for this choice relies on two arguments. Firstly, IMAT is certainly a predecessor of VMAT but it is a relatively old approach, somehow limited to few institutes because the absence of commercial and broadly available planning system and because its complex clinical workflow. Secondly, for Tomotherapy was excluded because of somehow opposite reasons. Its relatively wide spread and the existing literature is adundant. Inclu (...truncated)