Androgen receptor levels can predict response to androgen deprivation therapy

September 1, 2007

Investigators undertook a study to evaluate a possible relationship between androgen receptor levels and time to progression after starting ADT.

Having previously found that elevated androgen receptor levels in the prostatectomy sample were significantly associated with disease progression, investigators undertook a study to evaluate a possible relationship between androgen receptor levels and time to progression after starting ADT. Their analyses were based on data from a group of 63 men who underwent radical prostatectomy and were subsequently started on ADT for a biochemical recurrence or clinical progression. Thirty-two of the patients went on to be ADT failures, defined by a castrate rise in PSA.

The prostatectomy tissue specimens were assayed for androgen receptor content and other biomarkers using quantitative immunofluorescence and spectral imaging techniques. Those features, along with clinicopathologic variables, were analyzed using supervised machine learning algorithms for correlations with time to progression after starting ADT.

"Our findings on androgen receptor levels in this study and previous research provide an indication and an understanding of both response to therapy and progression of disease. They also provide the basis for an interesting hypothesis that androgen receptor levels in the prostatectomy sample, determined by quantitative immunofluorescence, may be used to identify men at high risk for progression or ADT failure, and thereby have an impact on the therapeutic plan and monitoring plan."

"The results are not completely surprising," commented Glenn J. Bubley, MD, director of genitourinary oncology, Beth Israel Deaconess Hospital, Boston, who was not involved in the study. "However, measuring androgen receptor levels in prostate cancer to predict response to therapy does go against established practice and conventional wisdom.

"Unlike the case for breast cancer, where measuring receptor levels is critically important, it was not thought to be useful in prostate cancer, as almost all cancers express androgen receptor. The difference in this study is that it used state-of-the-art techniques that seem to be able to quantify the amount of receptor expression. Should these techniques or variations of these techniques become clinically more widespread, this may represent a useful new marker for prostate cancer's response to hormonal therapy."