Article

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: 4.18). 12/2010; 82(1):228-34. DOI: 10.1016/j.ijrobp.2010.10.026
Source: PubMed

ABSTRACT 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.

Download full-text

Full-text

Available from: Martina Descovich, Mar 11, 2014
1 Follower
 · 
134 Views
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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 · 4.86 Impact Factor
  • Source
    • "Since the early reports of hypofractionation, there has been a steady increase in reports of hypofractionated radiotherapy for prostate cancer . Some have decreased the number of fractions modestly, and others have reduced it to only five sessions [41] [42] [43] [44] [45] [46] [47] [48] [49] [50]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: There are radiobiological rationales supporting hypofractionated radiotherapy for prostate cancer. The recent advancements in treatment planning and delivery allow sophisticated radiation treatments to take advantage of the differences in radiobiology of prostate cancer and the surrounding normal tissues. The preliminary results from clinical studies indicate that abbreviated fractionation programs can result in successful treatment of localized prostate cancer without escalation of late toxicity.
    03/2013; 2013:103547. DOI:10.1155/2013/103547
  • Source
    • "In contrast, in a multi-institutional CyberKnife SBRT clinical study (Meier et al., 2010), the PTV is covered at 36.25 Gy, but the prostate GTV receives at least 40 Gy. Even more confounding to direct comparisons is the HDR-like dosimetry used in some centers (Fuller, 2008; Jabbari et al., 2010) whereby the prescription dose is 38 Gy delivered in four fractions, but the delivered dose to the peripheral zone is much higher and the urethra is contoured and urethral dose constrained (Fuller, 2008; Jabbari et al., 2010). Also, in two recently published studies patients were treated every other day (King et al., 2009; Boike et al., 2011), which may impact the efficacy and toxicity due to repair that may take place in the 48-h period between fractions. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This study examines the efficacy and toxicity of two stereotactic body radiation therapy (SBRT) dose regimens for treatment of early prostate cancer. Forty-one patients treated with 35 Gy were matched with 41 patients treated with 36.25 Gy. Both patient groups received SBRT in five fractions over five consecutive days using the CyberKnife. Each group had 37 low-risk patients and 4 intermediate-risk patients. No statistically significant differences were present for age, prostate volume, PSA, Gleason score, stage, or risk between the groups. The dose was prescribed to the 83-87% isodose line to cover the prostate and a 5-mm margin all around, except 3 mm posteriorly. The overall median follow-up is 51 months (range, 45-58 months) with a median 54 and 48 months follow-up for the 35 and 36.25-Gy dose groups, respectively. One biochemical failure occurred in each group yielding a 97.5% freedom from biochemical failure. The PSA response has been favorable for all patients with a mean PSA of 0.1 ng/ml at 4-years. Overall toxicity has been mild with 5% late grade 2 rectal toxicity in both dose groups. Late grade 1 urinary toxicity was equivalent between groups; grade 2 urinary toxicity was 5% (2/41 patients) and 10% (4/41 patients) in the 35-Gy and 36.25-Gy dose groups (p = 0.6969), respectively. Overall, the highly favorable PSA response, limited biochemical failures, limited toxicity, and limited impact on quality of life in these low- to low-intermediate-risk patients are supportive of excellent long-term results for CyberKnife delivered SBRT.
    Frontiers in Oncology 12/2011; 1:49. DOI:10.3389/fonc.2011.00049
Show more