title: Are serial bone scans useful for the follow-up of clinically localized, low to intermediate grade prostate cancer managed with watchful observation alone?
abstract: OBJECTIVE
  To assess the predictive value of serial bone scans as a surveillance tool for bone metastasis in men with clinically localized prostate cancer and managed with watchful observation.
  
  
  METHODS
  A prospective single-arm study was conducted to assess the feasibility of a watchful observation protocol with selective delayed intervention for patients with clinically localized prostate cancer, i.e. T1b-T2bN0M0, a Gleason score of <or= 7 and a prostate-specific antigen (PSA) level of <or= 15 ng/mL. Patients were managed expectantly as long as they did not meet the empirically predefined criteria of clinical, histological or PSA progression. Bone scintigraphy was repeated every year for the first 2 years, then every 2 years thereafter if the patient remained on watchful observation. When the follow-up PSA level was > 15 ng/mL the patient underwent bone scintigraphy every year.
  
  
  RESULTS
  In all, 244 eligible patients were enrolled into the study. With a median follow-up of 30 months, 449 bone scans were taken (150 at baseline and 299 in follow-up evaluations); all 299 follow-up scans were negative for bone metastasis. Hence, the true rate of positive follow-up bone scans was estimated to be 0-1.0% (95% confidence). In all, 171 patients had at least one follow-up bone scan; of these, the number (%) of patients who had 1, 2, 3, 4 and >or= 5 follow-up scans was 89 (52), 53 (31), 17 (10), eight (4.7) and four (2.3), respectively. The PSA levels (ng/mL) corresponding to all follow-up bone scans were: 214 scans at PSA < 10, 61 at 10-14.9, 18 at 15-19.9 and six at >or= 20 (range 20.2-24.9). The probability of a negative bone scan was estimated to be 88-100% (95% confidence interval) when a PSA threshold of 15 ng/mL was used.
  
  
  CONCLUSIONS
  The probability of positive findings in serial bone scans in untreated, localized, low to intermediate grade prostate cancer was low when the follow-up PSA level remained < 15 ng/mL. Avoiding bone scans in this group of patients would translate into a significant cost saving and reduction in their psychological and physical burden. As for those with a follow-up PSA of> 15 ng/mL, the role of serial bone scintigraphy remains undefined, as a longer follow-up and a larger sample are needed.
authors.affiliation: Toronto-Sunnybrook Regional Cancer Centre, Ontario, Canada.
authors.forename: B K
authors.initials: BK
authors.lastname: Yap
authors.forename: R
authors.initials: R
authors.lastname: Choo
authors.forename: G
authors.initials: G
authors.lastname: Deboer
authors.forename: L
authors.initials: L
authors.lastname: Klotz
authors.forename: C
authors.initials: C
authors.lastname: Danjoux
authors.forename: G
authors.initials: G
authors.lastname: Morton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D015331:Cohort Studies; D018450:Disease Progression; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013669:Technetium Tc 99m Medronate
chemical_list: D019275:Radiopharmaceuticals; D017430:Prostate-Specific Antigen; D013669:Technetium Tc 99m Medronate