Adjuvant androgen deprivation therapy loses its therapeutic benefit after premature termination: an experience of combined modality treatment on prostate cancer.

Background: To investigate the effect of the premature termination of recommended androgen deprivation therapy (ADT) as an adjunct to radiotherapy.

Methods: Between December 2001 and March 2004, 92 patients with non-metastatic prostate cancer underwent primary, curative radiotherapy via an intensity-modulated technique. Four patients (5%) were treated with a dosage of 70.2 Gy, while 74 (80%) and 14 patients (15%) were treated to 72 and 75.6 Gy. Thirty patients (33%) received pelvic irradiation to 45 Gy as a part of their treatment. Seventy-nine patients (86%) also received variable ADT, but only 35 patients (38%) followed a strict protocol when on ADT. Biochemical failure was defined as nadir plus 2 ng/mL or if there was any clinical evidence of tumor recurrence.

Results: The median follow-up time was 37.5 months (20.4-57.8 months). The 3-year overall survival rate was 91.8%. The estimated 3 year recurrence-free survival rates were 100%, 88.9%, and 69.7% for the low, intermediate, and high risk groups, respectively. High risk group patients receiving ADT of an inappropriate length was the only significant risk factor correlated to disease recurrence. The 3-year recurrence-free survival rate was extremely poor (28.6%) in high risk group patients who received adjuvant ADT for less than 2 years. This was significantly worse than patients with the same risk who received long-term ADT (88.1%) or no adjuvant ADT (76.4%, p < 0.001).

Conclusions: Long-term adjuvant ADT after radiotherapy on high risk prostate cancer has no benefit if the duration is less than 2 years. Premature termination should be avoided.