Background: Long-term outcomes of dose-escalated intensity-modulated radiation therapy (IMRT) combined with neoadjuvant (NA) androgen deprivation therapy (ADT) under an early salvage policy in patients with locally advanced prostate cancer (LAPC) were evaluated.
Methods: Data from 120 patients with T3-T4N0M0 adenocarcinoma of the prostate treated with IMRT were analyzed. NA-ADT with a median duration of 6 months was provided in all cases. Seventy-eight Gy, at 2 Gy per fraction, was delivered to the prostate and seminal vesicles. Adjuvant ADT (A-ADT) was not provided for any patient following the completion of IMRT. Salvage ADT (S-ADT) commenced when PSA values >4 ng/ml.
Results: The median follow-up period was 97 months. S-ADT was initiated in 39 patients. The median PSA value at the initiation of S-ADT was 5.7 ng/ml. The 8-year biochemical relapse-free survival, prostate cancer-specific survival, overall survival and S-ADT-free rates were 53.2 % [95 % confidence interval (CI) 43.4, 62.1], 96.6 % (95 % CI 91.2, 98.7), 89.1 % (95 % CI 81.5, 93.7) and 66.6 % (95 % CI 60, 74.6), respectively. The estimated 8-year cumulative incidence rates of grade 2-3 late gastrointestinal, and grade 2-3 genitourinary toxicity were 7.6 and 10.7 %, respectively. No grade 4 toxicity was observed.
Conclusions: High-dose IMRT, combined with NA-ADT for LAPC, was associated with favorable long-term disease-specific and overall survival outcomes, despite non-provision of A-ADT under the early S-ADT provision policy. This approach may represent a viable alternative to uniform provision of long-term A-ADT, because two-thirds of the patients maintained ADT-free status over an 8-year period after IMRT. Prospective trials will be required.
Keywords: Intensity-modulated radiation therapy; Locally advanced prostate cancer; Neoadjuvant androgen deprivation therapy; Salvage androgen deprivation therapy; Timing of salvage therapy.