Duration of Androgen Deprivation Therapy Influences Outcomes for Patients Receiving Radiation Therapy Following Radical Prostatectomy.

BACKGROUND

Limited data exist to guide the use of androgen deprivation therapy (ADT) for men treated with radiation therapy (RT) after radical prostatectomy (RP). The optimal duration of ADT in this setting is unknown.

OBJECTIVE

To determine if the duration of ADT influences clinical outcomes for men receiving post-RP RT.

DESIGN, SETTING, AND PARTICIPANTS: A total of 680 men who received adjuvant radiation therapy (n=105) or salvage radiation therapy (n=575) between 1986 and 2010 at a single tertiary care institution were reviewed retrospectively. Median follow-up post-RT was 57.8 mo.

INTERVENTION

RT was delivered using three-dimensional conformal or intensity-modulated RT in 1.8-Gy fractions. For patients treated with ADT, >80% were treated with a gonadotropin-releasing hormone agonist with or without a nonsteroidal antiandrogen.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Biochemical failure (BF), distant metastasis (DM), prostate cancer-specific mortality (PCSM), and overall mortality were assessed using Kaplan-Meier analysis and propensity score analysis.

RESULTS AND LIMITATIONS

Overall, 144 patients (21%) received ADT with post-RP RT, most of whom had high-risk disease features such as Gleason score 8-10, seminal vesicle invasion, or pre-RT prostate-specific antigen >1 ng/ml. Median ADT duration was 12 mo (interquartile range: 6.0-23.7). Patients who received <12 mo of ADT had an association with increased BF (hazard ratio [HR]: 2.27; p=0.003) and DM (HR: 2.48; p=0.03) compared with patients receiving ≥12 mo of ADT. The 5-yr rates of DM were 6.0% and 23% for ≥12 and <12 mo of ADT, respectively. On propensity score analysis controlling for pretreatment and treatment-related factors, each month of ADT was associated with a decreased risk for BF (HR: 0.95; p=0.0004), DM (HR: 0.88; p=0.0004), and PCSM (HR: 0.90; p=0.037). These findings are limited by the retrospective nature of our analysis.

CONCLUSIONS

For men with high-risk disease features receiving ADT with post-RP RT, the duration of ADT is associated with clinical outcomes. Our findings suggest that for these men an extended course of ADT ≥12 mo may be preferable. Validation of our findings is needed.

PATIENT SUMMARY

We evaluated outcomes for men with high-risk disease features treated with androgen deprivation therapy (ADT) and radiotherapy after radical prostatectomy. Longer durations of ADT resulted in improved patient outcomes.