The relationship between the androgen receptor CAG repeat polymorphism length and the response to intermittent androgen suppression therapy for advanced prostate cancer
Objective:To determine whether the duration of the off-treatment interval in patients being treated with intermittent androgen deprivation therapy can be predicted by the length of the CAG trinucleotide repeat polymorphism in the androgen receptor.Methods:This is a companion study to a prospective randomized trial, NCIC CTG PR-7, comparing intermittent to continuous androgen deprivation therapy in men with PSA progression after radiation therapy. The duration of the first off-treatment interval was established for 76 participants randomized to the intermittent therapy arm of the trial. Androgen receptor CAG repeat polymorphism lengths were determined for these 76 participants. Statistical analysis was completed to determine a relationship between CAG repeat length and the duration of the off-treatment interval.Results:A significant correlation was not established (P=0.424) between androgen receptor CAG repeat length and the duration of the first off-treatment interval. Categorical analysis of CAG repeat lengths using 18 and 22 as cutoff points did not find any significant difference in the mean duration of the off-treatment interval between categories (P=0.672 and 0.774, respectively).Conclusion:No relationship was established between the duration of the first off-treatment interval and the CAG repeat length.