Jeffrey Kittel MD, Presenter: Nothing to Disclose

Purpose/Objective(s): To report efficacy and late toxicity for a closely-followed, single-institution cohort of patients treated with prostate brachytherapy (PI). Materials/Methods: From 1996-2007, 1,989 patients with low-, intermediate-, and high-risk prostate cancer (NCCN) were treated with PI under an IRB approved registry. All patients were treated with I-125 to a target dose of 144 Gy. Patient disease characteristics, comorbidities, and treatment parameters were recorded. Toxicities were assessed from a review of patients’ charts and via communication from patients and their referring physicians. Toxicity was scored according to a modified CTCAE scale, and late toxicity was defined as occurring > 6 months after PI. The rates of biochemical relapse-free survival (bRFS) and distant metastases free survival (DMFS) were calculated using actuarial analysis. Prostate cancer specific mortality (CSM) was calculated using cumulative incidence analysis. Cox proportional hazards regression was used to identify factors associated with late grade ≥ 3 GU toxicity and logistic regression was used for other endpoints. Patients with < 3 follow-up PSAs were excluded from analysis of bRFS and DMFS but were included in the analysis of all other endpoints. Results: The median follow-up was 6.8 years (yr) (range: 0-16.5 yr). Median age was 67 yr. Median D90 was 146 Gy. 18.2% received androgen deprivation. 61.3% of patients were classified as low risk, 29.8% were intermediate risk, and 8.9% were high risk. Median prostate volume was 35.19 cc (range: 9.67 - 178.93 cc). The 10 yr rates for bRFS, DMFS, and CSM for all patients in this cohort were 81.5%, 91.5%, 2.5%, respectively. The rates of late toxicity are shown in the table. On multivariate analysis, age (HR= 1.04, 95% CI= 1.01-1.06) and prostate length (HR= 1.74, 95% CI= 1.36-2.21) were significantly associated with increased risk of grade ≥ 3 GU toxicity. Increased BMI exhibited a mild protective effect (HR= 0.95, 95% CI= 0.91-0.99). No treatment parameters were significantly associated with late GU toxicity. The risk of incontinence was highly correlated with TURP: OR= 3.28 (95% CI= 1.80-5.98) for pre-PI TURP; OR= 10.95 (95% CI= 6.83-17.56) for post-PI TURP. There were too few GI events to identify factors associated with an increased risk. Conclusions: Prostate brachytherapy is an effective treatment for prostate cancer. Significant long-term toxicities are rare when performed according to published guidelines. Long-term Toxicity GU GI Overall rate grade ≥ 3 152 (7.6%) 17 (0.9%) Grade 3 140 (7.0%) 14 (0.7%) Grade 4 12 (0.6%) 2 (0.1%) Grade 5 0 (0%) 1 (0.1%) Any GU incontinence 176 (8.9%) - Post-PI TURP 81 (4.1%) - Rectal bleeding - 325 (16.3%) PI-related rectal bleeding - 35 (1.8%)

Kittel, J, Prostate Brachytherapy is Associated With Low Rates of Significant Long-term Toxicities.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14044084.html