title: Gross tumor volume and clinical target volume in prostate cancer: How do satellites relate to the index lesion.
abstract: OBJECTIVE
  There is an increasing interest for dose differentiation in prostate radiotherapy. The purpose of our study was to analyze the spatial distribution of tumor satellites inside the prostate.
  
  
  METHODS
  61 prostatectomy specimens were stained with H&E. Tumor regions were delineated by the uro-pathologist. Volumes, distances and cell densities of all delineated tumor regions were measured and further analyzed.
  
  
  RESULTS
  Multifocal disease was seen in 84% of the patients. The median number of tumor foci was 3. The median distance between the index lesion and the satellites was 1.0 cm, with a maximum of 4.4 cm. The index lesions accounted for 88% of the total tumor volume. The contribution of tumor foci<0.1 cm(3) to the total tumor volume was 2%. The median cell density of the index lesion and all satellites, regardless of size, were significantly higher than that of the prostate.
  
  
  CONCLUSIONS
  Satellites do not appear in a limited margin around the index lesion (GTV). Consequently, a fixed CTV margin would not effectively cover all satellites. Thus if the aim is to treat all tumor foci, the entire prostate gland should be considered CTV.
authors: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Birgit G
authors: BG
authors: Hollmann
authors: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Baukelien
authors: B
authors: van Triest
authors: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Ghazaleh
authors: G
authors: Ghobadi
authors: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Greetje
authors: G
authors: Groenendaal
authors: Department of Pathology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Jeroen
authors: J
authors: de Jong
authors: Department of Urology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Henk G
authors: HG
authors: van der Poel
authors: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Uulke A
authors: UA
authors: van der Heide
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D047368:Tumor Burden
keywords: Index lesion; Pathology; Prostate cancer; Radiotherapy; Satellites; Spatial distribution