Androgen receptor CAG repeat length and association with prostate cancer risk: results from the prostate cancer prevention trial.
OBJECTIVE
We investigated the association between the length of the polymorphic trinucleotide CAG microsatellite repeats in exon 1 of the AR gene and the risk of prostate cancer.


METHODS
This is a nested case-control study of 1,159 cases and 1,353 controls from the Prostate Cancer Prevention Trial, a randomized, placebo controlled trial testing whether the 5α-reductase inhibitor finasteride could decrease the 7-year prevalence of prostate cancer. During the course of the trial men underwent annual digital rectal examination and prostate specific antigen measurement. Prostate biopsy was recommended in all men with abnormal digital rectal examination or finasteride adjusted prostate specific antigen greater than 4.0 ng/ml. Cases were drawn from men with biopsy determined prostate cancer identified by for cause or end of study biopsy. Controls were selected from men who completed the end of study biopsy.


RESULTS
Mean CAG repeat length did not differ between cases and controls. The frequency distribution of cases and controls for the AR CAG repeat length was similar. There were no significant associations of CAG repeat length with prostate cancer risk when stratified by treatment arm (finasteride or placebo), or when combined. There was also no significant association between CAG repeat length and the risk of low or high grade prostate cancer.


CONCLUSIONS
There is no association of AR CAG repeat length with prostate cancer risk. Knowledge of AR CAG repeat length provides no clinically useful information to predict prostate cancer risk.
Medical Oncology Branch, National Cancer Institute, Bethesda, Maryland 20892, USA.
Douglas K
DK
Price
Cindy H
CH
Chau
Cathee
C
Till
Phyllis J
PJ
Goodman
Caitlin E
CE
Baum
Sandy B
SB
Ockers
Bevin C
BC
English
Lori
L
Minasian
Howard L
HL
Parnes
Ann W
AW
Hsing
Juergen K V
JK
Reichardt
Ashraful
A
Hoque
Catherine M
CM
Tangen
Alan R
AR
Kristal
Ian M
IM
Thompson
William D
WD
Figg
D000368:Aged; D016022:Case-Control Studies; D005091:Exons / Q000235:genetics; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic; D011944:Receptors, Androgen / Q000235:genetics*; D012307:Risk Factors
D011944:Receptors, Androgen