title: The diagnostic utility of the flare phenomenon on bone scintigraphy in staging prostate cancer.
abstract: OBJECTIVE
  Bone scintigraphy (BS) lacks sensitivity for detecting very early skeletal metastases (SM) in prostate cancer (PC) and is often limited by poor specificity. Also scintigraphic flare of SM can occur following effective treatment and mislead an early response assessment. We hypothesised that a flare reaction might amplify the signal from subclinical SM, increasing the sensitivity of BS and that the phenomenon may be specific for metastases.
  
  
  METHODS
  We conducted a prospective study to determine the frequency of the flare phenomenon in patients with metastatic PC starting hormone therapy and to explore its utility in patients with negative staging scans but considered at high risk of SM and in those with equivocal baseline BS abnormalities. Ninety-nine patients commencing first-line hormone therapy had repeat BS at 6 weeks to score a flare reaction.
  
  
  RESULTS
  Of 22 patients with unequivocal SM on the baseline scan, a flare occurred in 9 (41%). Of 36 high-risk localised prostate cancer patients with normal BS pre-treatment, the scan became positive for metastases at 6 weeks in 4 (11%). Of 41 patients with pre-treatment scintigraphic abnormalities of uncertain aetiology, a flare occurred in 8 cases (20%). All eight were confirmed to have SM by follow-up and imaging. Of the 33 remaining patients without a flare, 2 developed SM at 14 months and the remainder did not develop SM in a median follow-up period of 36 months.
  
  
  CONCLUSIONS
  The flare phenomenon following initial hormone therapy can be used to improve both sensitivity and specificity of BS in PC.
authors.affiliation: Department of Nuclear Medicine and PET, Royal Marsden Hospital, Downs Rd, Sutton, Surrey, SM2 5PT, UK. gary.cook@rmh.nhs.uk
authors.forename: Gary J R
authors.initials: GJ
authors.lastname: Cook
authors.forename: Ram
authors.initials: R
authors.lastname: Venkitaraman
authors.forename: Aslam S
authors.initials: AS
authors.lastname: Sohaib
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Lewington
authors.forename: Sue C
authors.initials: SC
authors.lastname: Chua
authors.forename: Robert A
authors.initials: RA
authors.lastname: Huddart
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Parker
authors.forename: David D
authors.initials: DD
authors.lastname: Dearnaley
authors.forename: Alan
authors.initials: A
authors.lastname: Horwich
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D006728:Hormones / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology*; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity
chemical_list: D006728:Hormones