A PROSPECTIVE ANALYSIS OF TIME TO NORMALIZATION OF SERUM TESTOSTERONE AFTER WITHDRAWAL OF ANDROGEN DEPRIVATION THERAPY

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Abstract
Purpose: Patients with prostate cancer are treated with neoadjuvant, adjuvant and intermittent androgen deprivation therapy. Prostate specific antigen (PSA) is altered during androgen deprivation therapy, and as a result the prognostic significance and accuracy of PSA values measured before serum testosterone has normalized are questionable because the patient is still effectively on androgen deprivation therapy. We determine the time it takes for serum testosterone to return to normal after withdrawal of androgen deprivation therapy. Materials and Methods: Serial serum testosterone was prospectively measured at 3-month intervals in 68 men after withdrawal of androgen deprivation therapy. The number of months to return to normal serum testosterone 270 ng./dl. or greater, was calculated for each patient. Patients were stratified according to duration of androgen deprivation, age and type of luteinizing hormone releasing hormone agonist used. Results: Median patient age was 71 years (range 46 to 88). Median time to normalization of testosterone was 7 months (range 1 to 58). At 3, 6 and 12 months 28%, 48% and 74% of men had normal serum testosterone, respectively. Serum testosterone took significantly longer to return to normal in patients on androgen deprivation therapy for 24 months or greater compared to those on therapy for less than 24 months (log-rank p = 0.0034). There was no statistical significance based on age or type of luteinizing hormone releasing hormone agonist used. Conclusions: Androgen deprivation has an effect on serum testosterone that extends beyond the cessation of treatment. Serum testosterone should be measured in all men until normalization. These results should be applied to the interpretation of PSA levels after withdrawal of androgen deprivation therapy. In addition, these data have implications regarding dose scheduling and definition of biochemical (PSA) failure after primary therapy.