Stereotactic radiotherapy of the prostate: fractionation and utilization in the United States

PURPOSE: To analyze the utilization and fractionation of extreme hypofractionation via stereotactic body radiotherapy (SBRT) in the treatment of prostate cancer. MATERIALS AND METHODS: Data was analyzed on men diagnosed with localized prostate cancer between 2004–2012 and treated with definitive-intent radiation therapy, as captured in the National Cancer Database. This database is a hospital-based registry that collects an estimated 70% of all diagnosed malignancies in the United States. RESULTS: There were 299,186 patients identified, of which 4,962 (1.7%) were identified as receiving SBRT as primary treatment. Of those men, 2,082 had low risk disease (42.0%), 2,201 had intermediate risk disease (44.4%), and 679 had high risk disease (13.7%). The relative utilization of SBRT increased from 0.1% in 2004 to 4.0% in 2012. Initially SBRT was more commonly used in academic programs, though as time progressed there was a shift to favor an increased absolute number of men treated in the community setting. Delivery of five separate treatments was the most commonly utilized fractionation pattern, with 4,635 patients (91.3%) receiving this number of treatments. The most common dosing pattern was 725 cGy × 5 fractions (49.6%) followed by 700 cGy × 5 fractions (21.3%). CONCLUSIONS: Extreme hypofractionation via SBRT is slowly increasing acceptance. Currently 700-725 cGy × 5 fractions appears to be the most commonly employed scheme. As further long-term data regarding the safety and efficacy emerges, the relative utilization of this modality is expected to continue to increase.

Clinical and biochemical outcomes of men undergoing radical prostatectomy or radiation therapy for localized prostate cancer

PURPOSE: We analyzed outcomes of patients with prostate cancer undergoing either radical retropubic prostatectomy (RRP) +/- salvage radiation or definitive radiation therapy (RT) +/- androgen deprivation. MATERIALS AND METHODS: From 2003-2010 there were 251 patients who underwent RRP and 469 patients who received RT (> or =7,560 cGy) for prostate cancer. Kaplan-Meier analysis was performed with the log-rank test to compare biochemical control (bCR), distant metastatic-free survival (DMPFS), and prostate cancer-specific survival (PCSS) between the two groups. RESULTS: The median follow-up was 70 months and 61.3% of the men were African American. For low risk disease the 6-year bCR were 90.3% for RT and 85.6% for RRP (p = 0.23) and the 6-year post-salvage bCR were 90.3% vs. 90.9%, respectively (p = 0.84). For intermediate risk disease the 6-year bCR were 82.6% for RT and 59.7% for RRP (p < 0.001) and 82.6% vs. 74.0%, respectively, after including those salvaged with RT (p = 0.06). For high risk disease, the 6-year bCR were 67.4% for RT and 41.3% for RRP (p < 0.001) and after including those salvaged with RT was 67.4% vs. 43.1%, respectively (p < 0.001). However, there were no significant differences between the two groups in regards to DMPFS or PCSS. CONCLUSION: Treatment approaches utilizing RRP +/- salvage radiation or RT +/- androgen deprivation yielded equivalent DMPFS and PCSS outcomes. Biochemical control rates, using their respective definitions, appeared equivalent or better in those who received treatment with RT.

Long-term tolerance and outcomes for dose escalation in early salvage post-prostatectomy radiation therapy

PURPOSE: To study the long-term outcomes and tolerance in our patients who received dose escalated radiotherapy in the early salvage post-prostatectomy setting. MATERIALS AND METHODS: The medical records of 54 consecutive patients who underwent radical prostatectomy subsequently followed by salvage radiation therapy (SRT) to the prostate bed between 2003-2010 were analyzed. Patients included were required to have a pre-radiation prostate specific antigen level (PSA) of 2 ng/mL or less. The median SRT dose was 70.2 Gy. Biochemical failure after salvage radiation was defined as a PSA level >0.2 ng/mL. Biochemical control and survival endpoints were analyzed using the Kaplan-Meier method. Univariate and multivariate Cox regression analysis were used to identify the potential impact of confounding factors on outcomes. RESULTS: The median pre-SRT PSA was 0.45 ng/mL and the median follow-up time was 71 months. The 4- and 7-year actuarial biochemical control rates were 75.7% and 63.2%, respectively. The actuarial 4- and 7-year distant metastasis-free survival was 93.7% and 87.0%, respectively, and the actuarial 7-year prostate cancer specific survival was 94.9%. Grade 3 late genitourinary toxicity developed in 14 patients (25.9%), while grade 4 late genitourinary toxicity developed in 2 patients (3.7%). Grade 3 late gastrointestinal toxicity developed in 1 patient (1.9%), and grade 4 late gastrointestinal toxicity developed in 1 patient (1.9%). CONCLUSION: In this series with long-term follow-up, early SRT provided outcomes and toxicity profiles similar to those reported from the three major randomized trials studying adjuvant radiation therapy.