Twenty-four-month postradiation prostate biopsies are strongly predictive of 7-year disease-free survival: results from a Canadian randomized trial.
BACKGROUND
The objective of this study was to evaluate the predictive value of prostate biopsies that were obtained 24 months after the completion of radiotherapy (RT) with respect to disease-free survival (DFS) in a randomized trial that compared 3 months versus 8 months of neoadjuvant hormone therapy before conventional dose external RT.


METHODS
From February 1995 to June 2001, 378 men were randomized to receive either 3 months or 8 months of combined flutamide and goserelin before they received 66 Gray of RT at 4 participating centers. By risk group, 26% of patients were categorized as low risk, 43% were categorized as intermediate risk, and 31% were categorized as high risk. The 2 treatment arms were balanced in terms of age, Gleason score, clinical tumor classification, risk group, and presenting prostate-specific antigen level. The median follow-up for the patients who remained alive was 6.6 years (range, 1.6-10.1 years). Of 361 evaluable patients, 290 patients remained alive. Post-RT prostate biopsies were performed between 24 and 30 months after the completion of RT in 3 of the 4 centers. Biopsies that had residual tumor with severe treatment effect were considered indeterminate, and biopsies that had minimal or no treatment effect were considered positive.


RESULTS
The 5-year rate of actuarial freedom from any failure for the 3-month arm versus the 8-month arm was 72% versus 75% (P = .18). The DFS for patients who had negative and indeterminate biopsies was similar. Two-year post-treatment biopsy status was a strong predictor of 5-year DFS rate (82% and 83% for negative and indeterminate biopsies, respectively, vs 27% for positive biopsies; P < .0001). Multivariate analysis indicated that biopsy status (P < .0001) and Gleason score (P < .0001) were the strongest determinates of biochemical DFS.


CONCLUSIONS
Two-year post-RT prostate biopsies were strongly predictive of subsequent DFS. Biopsies with severe treatment effect were considered negative.
Crook
Juanita M
JM
Department of Radiation Oncology, Princess Margaret Hospital, Toronto, Ontario, Canada. juanita.crook@rmp.uhn.on.ca
Malone
Shawn
S
Perry
Gad
G
Eapen
Libni
L
Owen
Julie
J
Robertson
Susan
S
Ludgate
Charles
C
Fung
Sharon
S
Lockwood
Gina
G
D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002170:Canada; D018572:Disease-Free Survival; D005485:Flutamide / Q000627:therapeutic use; D017273:Goserelin / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D016896:Treatment Outcome
D017273:Goserelin; D005485:Flutamide