Radiation Therapy for Local or Biochemical Recurrence Following Radical Prostatectomy in Patients with Prostate Cancer.

Introduction and objectives: To investigate outcomes of patients with biochemical or local recurrence, without distant metastasis, who received radiation therapy targeting the prostate bed at our hospital following radical prostatectomy for prostate cancer.

Methods: Patients suspected of recurrence after radical prostatectomy, indicated by an increase in PSA levels or other factors, were evaluated through imaging tests for local recurrence and distant metastasis. Those who showed no local recurrence received salvage radiotherapy to the prostate bed at a dose of 64.8 Gy. Patients with local recurrence received radiotherapy of 70.8 Gy to the site of local recurrence and 64.8 Gy to the prostate bed.

Results: Among 19 cases of local recurrence following radical prostatectomy, three out of nine patients who did not receive ADT experienced recurrence after local radiation therapy. In contrast, none of the ten patients who received ADT during radiation therapy experienced recurrence following treatment. No significant difference was observed in clinical recurrence-free survival between patients receiving radiation therapy alone and those receiving ADT during radiation therapy. (p = 0.302) Fifty-six of the 57 patients without local recurrence were evaluated regarding their PSA doubling time (PSADT). Those with a PSADT of 6 months or more at the time of recurrence following radical prostatectomy tended to show longer clinical recurrence-free survival after local radiation therapy compared with showing PSADT of less than 6 months. (p=0.06) Patients with local recurrence who were treated with escalated radiation doses did not show any difference in the incidence of radiotherapy-related gastrointestinal toxicity compared with patients without local recurrence.

Conclusion: Although this study was conducted at a single institution with a small sample size and a limited number of patients, ADT may be beneficial in preventing recurrence following radiation therapy for local recurrence after radical prostatectomy. When considering salvage radiation therapy for patients with biochemical recurrence following radical prostatectomy, PSADT may be useful.