Stereotactic Body Radiotherapy as Monotherapy or Post–External Beam Radiotherapy Boost for Prostate Cancer: Technique, Early Toxicity, and PSA Response

Department of Radiation Oncology, University of California San Francisco, San Francisco, California, USA.
International journal of radiation oncology, biology, physics (Impact Factor: 4.26). 12/2010; 82(1):228-34. DOI: 10.1016/j.ijrobp.2010.10.026
Source: PubMed


High dose rate (HDR) brachytherapy has been established as an excellent monotherapy or after external-beam radiotherapy (EBRT) boost treatment for prostate cancer (PCa). Recently, dosimetric studies have demonstrated the potential for achieving similar dosimetry with stereotactic body radiotherapy (SBRT) compared with HDR brachytherapy. Here, we report our technique, PSA nadir, and acute and late toxicity with SBRT as monotherapy and post-EBRT boost for PCa using HDR brachytherapy fractionation.
To date, 38 patients have been treated with SBRT at the University of California-San Francisco with a minimum follow-up of 12 months. Twenty of 38 patients were treated with SBRT monotherapy (9.5 Gy × 4 fractions), and 18 were treated with SBRT boost (9.5 Gy × 2 fractions) post-EBRT and androgen deprivation therapy. PSA nadir to date for 44 HDR brachytherapy boost patients with disease characteristics similar to the SBRT boost cohort was also analyzed as a descriptive comparison.
SBRT was well tolerated. With a median follow-up of 18.3 months (range, 12.6-43.5), 42% and 11% of patients had acute Grade 2 gastrourinary and gastrointestinal toxicity, respectively, with no Grade 3 or higher acute toxicity to date. Two patients experienced late Grade 3 GU toxicity. All patients are without evidence of biochemical or clinical progression to date, and favorably low PSA nadirs have been observed with a current median PSA nadir of 0.35 ng/mL (range, <0.01-2.1) for all patients (0.47 ng/mL, range, 0.2-2.1 for the monotherapy cohort; 0.10 ng/mL, range, 0.01-0.5 for the boost cohort). With a median follow-up of 48.6 months (range, 16.4-87.8), the comparable HDR brachytherapy boost cohort has achieved a median PSA nadir of 0.09 ng/mL (range, 0.0-3.3).
Early results with SBRT monotherapy and post-EBRT boost for PCa demonstrate acceptable PSA response and minimal toxicity. PSA nadir with SBRT boost appears comparable to those achieved with HDR brachytherapy boost.

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Available from: Martina Descovich, Mar 11, 2014
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    • "Preliminary data on the efficacy and safety of post-EBRT CyberKnife boost compared with HDR brachytherapy boost were introduced by Oermann et al. [2]. Recently, Jabbari et al. [25] reported that PSA response defined by nadir PSA was acceptable compared with the HDR brachytherapy boost group (median nadir PSA, 0.10 ng/mL vs. 0.09 ng/mL). However, these studies had relatively short follow-up periods from which to draw conclusions about the PSA response. "
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    ABSTRACT: In this retrospective study, we analyzed the outcomes of prostate cancer patients treated with the CyberKnife radiotherapy system (Accuray). Between 2007 and 2010, 31 patients were treated for prostate cancer by use of the CyberKnife radiotherapy system. After excluding six patients who were lost to follow-up, data for the remaining 25 patients were analyzed. Patients were divided into the CyberKnife monotherapy group and a postexternal beam radiotherapy boost group. Clinicopathologic features and treatment outcomes were compared between the groups. The primary endpoint was biochemical recurrence-free survival period based on the Phoenix definition. Toxicities were evaluated by using the Radiation Therapy Oncology Group scoring criteria. Of 25 patients, 17 (68%) and 8 (32%) were classified in the monotherapy and boost groups, respectively. With a median follow-up of 29.3 months, most of the toxicities were grade 1 or 2 except for one patient in the boost group who experienced late grade 3 gastrointestinal toxicity. The overall biochemical recurrence rate was 20% (5/25) and the median time to biochemical recurrence was 51.9 months. None of the patients with low or intermediate risk had experienced biochemical recurrence during follow-up. Among D'Amico high-risk populations, 16.7% (1/6) in the monotherapy group and 50.0% (4/8) in the boost group experienced biochemical recurrence. Our data support that prostate cancer treatment by use of the CyberKnife radiotherapy system is feasible. The procedure can be a viable option for managing prostate cancer either in a monotherapy setting or as a boost after conventional radiotherapy regardless of the patient's risk stratification.
    Korean journal of urology 03/2014; 55(3):172-7. DOI:10.4111/kju.2014.55.3.172
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    • "The specifics of the SBRT technique have been described previously [25], but briefly, the dose and fractionation are based on the UCSF HDR monotherapy experience, with 38 Gy in 4 fractions of 9.5 Gy to an isodose of approximately 60-80% and a 2 mm expansion for patient setup and motion. Prior to treatment, 3 fiducial markers were inserted into the prostate, enabling real-time tracking of and automatic beam adjustment for intrafraction prostate motion. "
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    ABSTRACT: Patients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.Materials/methods: 75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997-2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT. The median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005). Patients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control.
    Radiation Oncology 02/2014; 9(1):42. DOI:10.1186/1748-717X-9-42 · 2.55 Impact Factor
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    • "The current evidence for SABR as primary treatment for localized PCa is mainly in the form of small trials or series, 13 using Cyberknife™ and 6 using linacs [18] [19] [20] [21] [22] [23] [24]. There is variation in dose-fractionation schedules, organ-at-risk constraints, use of androgen deprivation, CTV–PTV margins, IGRT techniques and inclusion of SV within the CTV (most often the SV are not treated, even in non-low risk patients). "
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    ABSTRACT: To develop a class solution for prostate Stereotactic Ablative Radiotherapy (SABR) using Volumetric Modulated Arc Therapy (VMAT). Seven datasets were used to compare plans using one 360° arc (1FA), one 210° arc (1PA), two full arcs and two partial arcs. Subsequently using 1PA, fifteen datasets were compared using (i) 6mm CTV-PTV margins, (ii) 8mm CTV-PTV margins and (iii) including the proximal SV within the CTV. Monaco™ 3.2 (Elekta™) was used for planning with the Agility™ MLC system (Elekta™). Highly conformal plans were produced using all four arc arrangements. Compared to 1FA, 1PA resulted in significantly reduced rectal doses, and monitor units and estimated delivery times were reduced in six of seven cases. Using 6mm CTV-PTV margins, planning constraints were met for all fifteen datasets. Using 8mm margins required relaxation of the uppermost bladder constraint in three cases to achieve adequate coverage, and, compared to 6mm margins, rectal and bladder doses significantly increased. Including the proximal SV required relaxation of the uppermost bladder and rectal constraints in two cases, and rectal and bladder doses significantly increased. Prostate SABR VMAT is optimal using 1PA. 6mm CTV-PTV margins, compatible with daily fiducial-based IGRT, are consistently feasible in terms of target objectives and OAR constraints.
    Radiotherapy and Oncology 12/2013; 110(2). DOI:10.1016/j.radonc.2013.10.036 · 4.36 Impact Factor
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