title: PSA doubling time of prostate carcinoma managed with watchful observation alone.
abstract: OBJECTIVE
  To study prostate-specific antigen (PSA) doubling time of untreated, favorable grade, prostate carcinoma.
  
  
  METHODS
  A prospective single-arm cohort study has been in progress to assess the feasibility of a watchful observation protocol with selective delayed intervention using clinical, histologic, or PSA progression as treatment indication in untreated, localized, favorable grade prostate adenocarcinoma (T1b-T2bN0 M0, Gleason Score < or = 7, and PSA < or = 15 ng/mL). Patients are conservatively managed with watchful observation alone, as long as they do not meet the arbitrarily defined disease progression criteria. Patients are followed regularly and undergo blood tests including PSA at each visit. PSA doubling time (Td) is estimated from a linear regression of ln(PSA) on time, assuming a simple exponential growth model.
  
  
  RESULTS
  As of March 2000, 134 patients have been on the study for a minimum of 12 months (median, 24; range, 12-52) and have a median frequency of PSA measurement of 7 times (range, 3-15). Median age is 70 years. Median PSA at enrollment is 6.3 (range, 0.5-14.6). The distribution of Td is as follows: <2 years, 19 patients; 2-5 years, 46; 5-10 years, 25; 10-20 years, 11; 20-50 years, 6; > 50 years, 27. The median Td is 5.1 years. In 44 patients (33%), Td is greater than 10 years. There was no correlation between Td and patient age, clinical T stage, Gleason score, or initial PSA level.
  
  
  CONCLUSIONS
  Td of untreated prostate cancer varies widely. In our cohort, 33% have Td > 10 years. Td may be a useful tool to guide treatment intervention for patients managed conservatively with watchful observation alone.
authors.affiliation: Toronto-Sunnybrook Regional Cancer Center, University of Toronto, Toronto, Ontario, Canada. richard.choo@tsrcc.on.ca
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 C
authors.initials: GC
authors.lastname: Morton
authors.forename: E
authors.initials: E
authors.lastname: Rakovitch
authors.forename: N
authors.initials: N
authors.lastname: Fleshner
authors.forename: P
authors.initials: P
authors.lastname: Bunting
authors.forename: L
authors.initials: L
authors.lastname: Kapusta
authors.forename: G
authors.initials: G
authors.lastname: Hruby
mesh_terms: D000230:Adenocarcinoma / Q000097:blood* / Q000473:pathology / Q000628:therapy; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D018450:Disease Progression; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000628:therapy; D013997:Time Factors
chemical_list: D017430:Prostate-Specific Antigen