Adjuvant high-dose intensity-modulated radiotherapy after radical prostatectomy for prostate cancer: clinical results in 104 patients

Abstract

Background: Approximately 25% of patients treated with adjuvant radiotherapy (RT) will develop a biochemical failure within 5 yr after RT when doses of 60-64 Gray (Gy) are used.

Objective: To report on the safety and biochemical outcome of adjuvant intensity-modulated RT (IMRT) with doses >70 Gy.

Design, setting, and participants: Between 1999 and 2008, 104 patients underwent radical prostatectomy (RP) followed by adjuvant IMRT with or without androgen deprivation (AD) with a median follow-up of 36 mo. Indications for adjuvant IMRT were capsule perforation, seminal vesicle invasion (SVI) and/or positive surgical margins at prostatectomy specimen. All patients were irradiated at a single tertiary academic centre. AD was initiated on the basis of SVI, a preprostatectomy prostate-specific antigen level >20 ng/ml, Gleason score > or = 4+3 (n=36), or personal preference of the referring urologist (n=32).

Intervention: A median dose of 74 Gy was prescribed to the planning target volume using IMRT in all patients. AD consisted out of a luteinising hormone-releasing hormone analogue for 6 mo.

Measurements: We report on acute and late toxicity, biochemical relapse-free survival (bRFS), and clinical progression. The Kaplan-Meier method was used to estimate bRFS. Univariate analysis was used to examine the influence of patient- and treatment-related factors on bRFS.

Results and limitations: With respect to acute toxicity, no patients developed grade 3 gastrointestinal (GI) toxicity, and eight patients developed grade 3 genitourinary (GU) toxicity (8%). With respect to late toxicity, no patients developed grade 3 GI toxicity, and four patients (4%) developed grade 3 GU toxicity. A urethral stricture was observed in six patients (6%). The 3- and 5-yr actuarial bRFS was 93%. On univariate analysis, bRFS rates were worse when SVI (p<0.02), Gleason score > or = 4+3 (p<0.02), or negative surgical margins (p<0.02) were present. AD did not influence bRFS. Six patients had a clinical relapse.

Conclusions: Adjuvant high-dose IMRT after prostatectomy is safe and bRFS is excellent.