Christopher R. King

46 Background: Stereotactic body radiotherapy (SBRT) for high-risk prostate cancer (CaP) remains investigational not only due to undetermined efficacy but also due to concerns for the potential toxicity when the treatment volumes extend beyond the prostate gland itself. Methods: Men with high-risk CaP, as defined by Gleason score > = 8, clinical stage T3-T4, or initial PSA > = 20 ng/mL, were enrolled on a multicenter phase II trial and were treated with 40 Gy to prostate and 25 Gy to pelvic nodes in 5 fractions and 9 months neoadjuvant and concurrent ADT. Treatment with ADT and pelvic nodal radiation was at the discretion of the treating physician. Follow-up assessment was with CTCAE v4 and Expanded Prostate Composite Index (EPIC). Results: A total of 61 patients were treated, with a median follow-up of 12 months. Forty (64.4%) received ADT and 23 (37.1%) received nodal radiation. The median initial PSA was 8.1 ng/mL and 8% of patients had clinical T3-T4 disease; 45.9% and 39.3% had Gleason score 8 and 9-10 disease, respectively. No grade 3 or higher toxicities were seen. Rates of acute and late grade 2 genitourinary toxicities were 13.1% and 6.7%, respectively; rates of acute and late grade 2 gastrointestinal toxicities were 6.6% and 8.2%, respectively. Mean changes in EPIC urinary incontinence, urinary obstructive, and bowel domain scores at 4 months were -0.35, +1.44, and -2.38, respectively. For the 32 patients with evaluable EPIC scores at 12 months, mean changes on EPIC urinary incontinence, urinary obstructive, and bowel domain scores at 4 months were -1.04, -2.70, and -6.76, respectively. The percentages of patients with minimum clinically important change in EPIC urinary incontinence, urinary obstructive, and bowel domain scores at 4 months were 11.9%, 21.4%, and 26.2%, respectively. At 12 months, these figures were 13.9%, 30.6% and 27.8%. The receipt of ADT and/or nodal radiation had no significant effect on either physician- or patient-reported toxicity profiles (p > 0.1, Fisher’s exact test). Conclusions: SBRT regimens can be safely utilized to deliver the entire course in 5 treatment days in patients with high-risk localized CaP. Clinical trial information: NCT02296229.

Objective:Compared with standard, whole-gland (WG) therapies for prostate cancer, focal approaches may provide equivalent oncologic outcomes with fewer adverse effects. The purpose of this study was to compare organ-at-risk (OAR) dosimetry between hemigland (HG) and WG stereotactic body radiotherapy (SBRT) plans.Methods:Volumetric-modulated arc radiotherapy-based SBRT plans were designed to treat the left HG, right HG and WG in eight patients, using five fractions of 8 Gy. OARs of interest included the contralateral HG, rectum, urinary bladder, urethra, penile bulb and contralateral neurovascular bundle.Results:Rectal V80% (the percentage of a normal structure receiving a dose of 80%) and V90% were significantly lower with HG plans than with WG plans (median values of 4.4 vs 2.5 cm3 and 2.1 vs 1.1 cm3, respectively, p < 0.05 by Student's t-test). Bladder V50% was also reduced significantly in HG plans (32.3 vs 17.4 cm3, p < 0.05), with a trend towards reduction of V100% (3.4 vs 1.3 cm3, p = 0.09). Urethra...

118 Background: Although American Society for Radiation Oncology (ASTRO) guidelines support single fraction radiation treatment for uncomplicated bone metastases, it is rarely used. Methods: We used modified RAND/UCLA appropriateness methodology to understand how radiation oncologists make decisions about single fraction treatment to inform quality improvement. We focused on uncomplicated bone metastases (defined by relevant RCT exclusion criteria) without prior irradiation, pathologic fracture, or spinal cord compression. Eight radiation oncologists with varying sub-specialties were provided ASTRO guidelines, a summary table of RCT’s and recent research on current practices. They rated the appropriateness of 8Gy Single Fraction treatment and 4 alternative regimens for clinical cases before and after a panel discussion that also included three palliative care physicians. Clinical cases varied by location of metastases (spine, humeral head, femur, rib), size of metastases, patient prognosis, travel distance to treatment site, and patient age. We report findings based on final median appropriateness ratings and qualitative evaluation of discussion. Results: Single fraction treatment (8Gy) was rated as the most appropriate treatment, regardless of other factors if prognosis was 6 months or less. However, participants noted that prognostic information is often not available at the point of care. Use of greater than 10 fractions was rated as inappropriate regardless of other factors. Older age and travel distance were factors that lead to favoring 8Gy single fraction treatment. There was less consensus concerning single fraction treatment and favoring of other treatment approaches for lesions located on the spine, especially large lesions, and for patients with oligometastases and a longer prognosis where goals may include local tumor control in addition to palliation. Conclusions: Improving specification and communication of prognostic information is an important quality improvement target to enhance the patient-centered nature of care for patients with painful bone metastases.

9 Background: The purpose of this study is to report biochemical relapse-free survival (bRFS) rates for a group of localized prostate cancer patients from a pooled multi-institutional dataset with at least 5 years follow-up after stereotactic body radiotherapy (SBRT). Methods: The outcome data from 1101 patients treated with SBRT between 2003 and 2011 were pooled from 8 institutions. A subset of 135 cases had a minimum 5 years follow-up. All 135 cases had clinical stage T1 or T2A disease. The distribution by Gleason score (GS) was 38 Gy in 11%. Androgen deprivation therapy was given to 21% of patients. Biochemical relapse, defined as a rise > 2 ng/ml above nadir, was determined in a total of 4 failures. Results: The median follow-up for all 135 cases was 60 months (range 60 to 72). For all patients, the bRFS rate at 5 years was 97%. The 5-year actuarial bRFS rates for GS < 6, and Gleason score 7 were 98%, and 92%, respectively (p=0.15). The 5-year actuarial bRFS rates for low versus intermediate/high-risk patients were 99% and 93%, respectively (p=0.11). The 5-year actuarial bRFS rates for patients receiving 35 Gy versus >36.25 Gy were 93% and 100%. No difference in bRFS was observed with the use of androgen deprivation (p=0.78). Multivariate analysis showed only GS to be an independent predictor of relapse (p=0.03); iPSA (p=0.10) and radiation dose (0.97) were not. Conclusions: In a relatively large cohort of localized prostate cancer patients treated with SBRT, long follow-up period (>5 years), excellent efficacy was demonstrated with 97% of patients being free from relapse. For low and intermediate risk cases, these results compare favorably with other modalities with similar follow-up periods. Although a trend for worse outcome was seen with total radiation doses of 35 Gy, this was not confirmed on multivariate analysis.