title: Technological advances in radiotherapy of rectal cancer: opportunities and challenges.
abstract: This review summarizes the available evidence for the use of modern radiotherapy techniques for chemoradiotherapy for rectal cancer, with specific focus on intensity-modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) techniques.
  
  
  
  The dosimetric benefits of IMRT and VMAT are well established, but prospective clinical studies are limited, with phase I-II studies only. Recent years have seen the publication of a few larger prospective patient series as well as some retrospective cohorts, several of which include much needed late toxicity data. Overall results are encouraging, as toxicity levels - although varying across reports - appear lower than for 3D conformal radiotherapy. Innovative treatment techniques and strategies which may be facilitated by the use of IMRT/VMAT include simultaneously integrated tumour boost, adaptive treatment, selective sparing of specific organs to enable chemotherapy escalation, and nonsurgical management.
  
  
  
  Few prospective studies of IMRT and VMAT exist, which causes uncertainty not just in regards to the clinical benefit of these technologies but also in the optimal use. The priority for future research should be subgroups of patients who might receive relatively greater benefit from innovative treatment techniques, such as patients receiving chemoradiotherapy with definitive intent and patients treated with dose escalation.
authors.affiliation: aDepartment of Oncology, Rigshospitalet, University of Copenhagen bDanish Colorectal Cancer Center South, Vejle Hospital, Institute of Regional Health Research, University of Southern Denmark, Denmark cDepartment of Clinical Oncology, University of Leeds, Leeds Cancer UK Centre, UK.
authors.forename: Ane L
authors.initials: AL
authors.lastname: Appelt
authors.forename: David
authors.initials: D
authors.lastname: Sebag-Montefiore
mesh_terms: D059248:Chemoradiotherapy; D017321:Clinical Trials, Phase I as Topic; D017322:Clinical Trials, Phase II as Topic; D006801:Humans; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*