title: Hybrid (CT/MRI based) vs. MRI only based image-guided brachytherapy in cervical cancer: Dosimetry comparisons and clinical outcome.
abstract: OBJECTIVE
  Limited access to MRI has restricted implementation of MRI-based image-guided brachytherapy (IGBT) in line with GEC-ESTRO guidelines in many centers. This work reports our experience using an alternative CT/MRI based (hybrid) approach for IGBT, dosimetry comparisons, and its impact on long-term clinical outcome and major toxicity.
  
  
  METHODS
  Seventy-six patients diagnosed with locally advanced cervical cancer between May 2008 and May 2012 treated with IGBT were analyzed. The hybrid approach is the default IGBT approach during this study period. Forty-nine had hybrid approach and 27 patients had "3-fraction conformal MRI" approach (17 within EMBRACE study). Treatment consisted of 48 Gy in 24 fractions of conformally planned external beam radiotherapy with weekly cisplatin followed by three weekly fractions of brachytherapy to high-risk clinical target volume (HR-CTV). All patients have a prebrachytherapy MRI 4 days before treatment and with the applicators in place on Fraction 1. MRI only or CT is used for subsequent fractions. Using image registration techniques and the assumption that the HR-CTV is fixed with respect to the applicator, the HR-CTV from MRI at Fraction 1 is transferred onto subsequent fraction CT image sets for the hybrid approach.
  
  
  RESULTS
  Median follow-up was 41 months (range, 23-71 months). Excellent 3-year local control, overall progression-free survival, and overall survival of 92.6%, 78.8%, and 77.7% were seen with the hybrid approach and 92.2%, 66.3%, and 69.6% with a 3-fraction conformal MRI approach, respectively. Dosimetry achieved and late toxicity rates were comparable in the two groups.
  
  
  CONCLUSIONS
  Hybrid IGBT in locally advanced cervical cancer offers an alternative approach when access to MRI restricts implementation of IGBT.
authors.affiliation: Department of Clinical Oncology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK. Electronic address: ee_siang@hotmail.com.
authors.forename: Ee Siang
authors.initials: ES
authors.lastname: Choong
authors.affiliation: Department of Medical Physics and Engineering, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Bownes
authors.affiliation: Department of Clinical Oncology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Hima Bindu
authors.initials: HB
authors.lastname: Musunuru
authors.affiliation: Department of Clinical Oncology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Sree
authors.initials: S
authors.lastname: Rodda
authors.affiliation: Department of Medical Physics and Engineering, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Richardson
authors.affiliation: Department of Medical Physics and Engineering, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Bashar
authors.initials: B
authors.lastname: Al-Qaisieh
authors.affiliation: Department of Radiology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Swift
authors.affiliation: Department of Clinical Oncology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Orton
authors.affiliation: Department of Clinical Oncology, St James's Institute of Oncology, St James's University Hospital, Leeds, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Cooper
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D059248:Chemoradiotherapy; D002945:Cisplatin / Q000627:therapeutic use; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D015642:Radiology, Interventional / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin
keywords: Cervical cancer; Image-guided brachytherapy