title: Optimal contouring of seminal vesicle for definitive radiotherapy of localized prostate cancer: comparison between EORTC prostate cancer radiotherapy guideline, RTOG0815 protocol and actual anatomy.
abstract: BACKGROUND
  Intermediate- to-high-risk prostate cancer can locally invade seminal vesicle (SV). It is recommended that anatomic proximal 1-cm to 2-cm SV be included in the clinical target volume (CTV) for definitive radiotherapy based on pathology studies. However, it remains unclear whether the pathology indicated SV extent is included into the CTV defined by current guidelines. The purpose of this study is to compare the volume of proximal SV included in CTV defined by EORTC prostate cancer radiotherapy guideline and RTOG0815 protocol with the actual anatomic volume.
  
  
  METHODS
  Radiotherapy planning CT images from 114 patients with intermediate- (36.8%) or high-risk (63.2%) prostate cancer were reconstructed with 1-mm-thick sections. The starting and ending points of SV and the cross sections of SV at 1-cm and 2-cm from the starting point were determined using 3D-view. Maximum (D1H, D2H) and minimum (D1L, D2L) vertical distance from these cross sections to the starting point were measured. Then, CTV of proximal SV defined by actual anatomy, EORTC guideline and RTOG0815 protocol were contoured and compared (paired t test).
  
  
  RESULTS
  Median length of D1H, D1L, D2H and D2L was 10.8 mm, 2.1 mm, 17.6 mm and 8.8 mm (95th percentile: 13.5mm, 5.0mm, 21.5mm and 13.5mm, respectively). For intermediate-risk patients, the proximal 1-cm SV CTV defined by EORTC guideline and RTOG0815 protocol inadequately included the anatomic proximal 1-cm SV in 62.3% (71/114) and 71.0% (81/114) cases, respectively. While for high-risk patients, the proximal 2-cm SV CTV defined by EORTC guideline inadequately included the anatomic proximal 2-cm SV in 17.5% (20/114) cases.
  
  
  CONCLUSIONS
  SV involvement indicated by pathology studies was not completely included in the CTV defined by current guidelines. Delineation of proximal 1.4 cm and 2.2 cm SV in axial plane may be adequate to include the anatomic proximal 1-cm and 2-cm SV. However, part of SV may be over-contoured.
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. 18810534009@139.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Qi
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. gao7777@139.com.
authors.forename: Xian-Shu
authors.initials: XS
authors.lastname: Gao
authors.affiliation: Department of Oral and Maxillofacial Radiology, Field of Tumor Biology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. asaumi@md.okayama-u.ac.jp.
authors.forename: Junichi
authors.initials: J
authors.lastname: Asaumi
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. 13811203207@139.com.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. 13718895126@139.com.
authors.forename: Hong-Zhen
authors.initials: HZ
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. shandianmcqueen@163.com.
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Ma
authors.affiliation: Department of Radiation Oncology, Peking University First Hospital, Beijing, China. zhaobo0410@yeah.net.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Department of Radiology, Peking University First Hospital, Beijing, China. redwindowlfy@163.com.
authors.forename: Fei-Yu
authors.initials: FY
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, Chicago, IL, USA. dian_wang@rush.edu.
authors.forename: Dian
authors.initials: D
authors.lastname: Wang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic / Q000592:standards*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012669:Seminal Vesicles / Q000033:anatomy & histology*