Stereotactic body radiotherapy for localized prostate cancer: Pooled analysis from a multi-institutional consortium of prospective phase II trials

King, Christopher R.; Freeman, Dan; Kaplan, Irving; Fuller, Donald B.; Bolzicco, Giampaolo; Collins, Sean P.; Meier, R.; Wang, Jason; Kupelian, Patrick A.; Steinberg, Michael L.; Katz, Alan J.

doi:10.1016/j.radonc.2013.08.030

Cited by 414 publications

(321 citation statements)

References 21 publications

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“…All of the treatment plans developed using each collimator type met the critical organ dose constraint requirements set forth in a previous report 5. In the MLC plans, V50% for the bladder is about 30% lower than it is in the circular collimator plans, and this difference is statistically significant.…”

Section: Resultsmentioning

confidence: 87%

“…The prescription dose was 36.25 Gy in 95% of the PTV and was delivered in five fractions, as in extreme hypofractionated radiation therapy. The parameters, such as the PTV margin, prescription dose, and treatment fraction number, were identical to those used in the prospective phase II trials conducted by King et al5 Moreover, the dose – volume histogram (DVH) goals used for the critical tissues, which are described hereinafter, were set in accordance with those reported by King et al5 The rectum DVH goals were V50% < 50% (i.e., the volume receiving 50% of the prescribed dose was <50%), V80% < 20%, V90% < 10%, and V100% < 5%. The bladder DVH goals were V50% < 40% and V100% < 10%.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, stereotactic body radiation therapy (SBRT) has been used clinically for prostate cancer treatment because the α / β ‐ratio of the prostate is lower than those of the surrounding late‐responding normal tissues 5, 6. Most of the data reported for prostate SBRT have been acquired using CyberKnife (Accuray, Inc., Sunnyvale, CA, USA), which is the only commercially available robotic radiosurgery system 6.…”

Section: Introductionmentioning

confidence: 99%

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Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

Tomida

Kamomae

Suzuki

et al. 2017

J Applied Clin Med Phys

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Stereotactic body radiation therapy (SBRT) using recently introduced multileaf collimators (MLC) is preferred over circular collimators in the treatment of localized prostate cancer. The objective of this study was to assess the clinical usefulness of MLCs in prostate SBRT by comparing the effectiveness of treatment plans using fixed collimators, variable collimators, and MLCs and by ensuring delivery quality assurance (DQA) for each. For each patient who underwent conventional radiation therapy for localized prostate cancer, mock SBRT plans were created using a fixed collimator, a variable collimator, and an MLC. The total MUs, treatment times, and dose–volume histograms of the planning target volumes and organs at risk for each treatment plan were compared. For DQA, a phantom with a radiochromic film or an ionization chamber was irradiated in each plan. We performed gamma‐index analysis to evaluate the consistency between the measured and calculated doses. The MLC‐based plans had an ~27% lower average total MU than the plans involving other collimators. Moreover, the average estimated treatment time for the MLC plan was 31% and 20% shorter than that for the fixed and variable collimator plans respectively. The gamma‐index passing rate in the DQA using film measurements was slightly lower for the MLC than for the other collimators. The DQA results acquired using the ionization chamber showed that the discrepancies between the measured and calculated doses were within 3% in all cases. The results reinforce the usefulness of MLCs in robotic radiosurgery for prostrate SBRT treatment planning; most notably, the total MU and treatment time were both reduced compared to the cases using other types of collimators. Moreover, although the DQA results based on film dosimetry yielded a slightly lower gamma‐index passing rate for the MLC than for the other collimators, the MLC accuracy was determined to be sufficient for clinical use.

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Section: Resultsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

Tomida

Kamomae

Suzuki

et al. 2017

J Applied Clin Med Phys

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“…In this study, we looked specifically at the consequences of limiting the upper dose to the PTV for low‐ and intermediate‐risk prostate cancer VMAT treatment plans. We investigated this site because (a) ablative doses are generally acceptable for prostate radiation therapy,8, 9, 10, 11, 12 which suggests minimal risk of toxicity from overdosing the PTV exclusively (within reason), (b) it is a site suggested by Craft et al.,5 and (c) prostate treatments are extremely common and make up a major fraction of the clinical workload for many clinics. We conducted a treatment planning study with a cohort of 17 anonymized VMAT patients using our clinical protocol for prostate cancer patients and compared optimization with and without an upper dose constraint on the PTV, which would be thought to be the best case scenario in terms of OAR sparing.…”

Section: Introductionmentioning

confidence: 99%

A quantitative assessment of the consequences of allowing dose heterogeneity in prostate radiation therapy planning

Sun

Smith

Ghose

et al. 2018

J Applied Clin Med Phys

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Target dose uniformity has been historically an aim of volumetric modulated arc therapy (VMAT) planning. However, for some sites, this may not be strictly necessary and removing this constraint could theoretically improve organ‐at‐risk (OAR) sparing and tumor control probability (TCP). This study systematically investigates the consequences of PTV dose uniformity that results from the application or removal of an upper dose constraint (UDC) in the inverse planning process for prostate VMAT treatments. OAR sparing, target coverage, hotspots, and plan complexity were compared between prostate VMAT plans with and without the PTV UDC optimized using the progressive resolution optimizer (PRO, Varian Medical Systems, Palo Alto, CA). Removing the PTV UDC, the median D1cc reached 144.6% for the CTV and the PTV, and an average increase of 3.2% TCP was demonstrated, while CTV and PTV coverage evaluated by D99% was decreased by less than 0.6% with statistical significance. Moreover, systematic improvement in the rectum dose volume histograms was shown (a 5–10% decrease in the volume receiving 50% to 75% prescribed dose), resulting in an average decrease of 1.3% (P < 0.01) in the rectum normal tissue complication probability. Additional consequences included potentially increased dose to the urethra as evaluated by PTV D0.035cc (median: 153.4%), delivering 283 extra monitor units (MUs), and slightly higher degrees of modulation. In general, the results were consistent when a different optimizer (Photon Optimizer, Varian Medical Systems) was used. In conclusion, removing the PTV UDC is acceptable for localized prostate cases given the systematic improvement of rectal dose and TCP. It can be particularly useful for cases that do not meet the rectum dose constraints with the PTV UDC on. This comes with the foreseeable consequences of increased dose heterogeneity in the PTV and an increase in MUs and plan complexity. It also has a higher requirement for reproducing the position and size of the target and OARs during treatment. Finally, with the PTV UDC completely removed, in some cases the maximum doses within the PTV did approach levels that may be of concern for urethral toxicity and therefore in clinical implementation it may still be necessary to include a PTV UDC, but one based on limiting toxicity rather than enforcing dose homogeneity.

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“…These have shown that 20–28 days fractionation schedules result in approximately equivalent biochemical control and rectal toxicities compared with 37–39 days conventional fractionation regimens. Stereotactic body radiation therapy (SBRT) has been increasingly explored for prostate treatment, often on a platform including some degree of real‐time imaging to reduce the impact of intrafraction motion 6. The need for such specialised equipment may impede the wider application of prostate SBRT in the community setting.…”

Section: Introductionmentioning

confidence: 99%

Rectal protection in prostate stereotactic radiotherapy: a retrospective exploratory analysis of two rectal displacement devices

Wilton

Richardson

Keats³

et al. 2017

J of Medical Radiation Sci

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IntroductionHigh rectal doses are associated with increased toxicity. A rectal displacement device (RDD) reduces rectal dose in prostate stereotactic body radiation therapy (SBRT). This study investigates any dosimetric difference between two methods of rectal displacement (Rectafix and SpaceOAR) for prostate SBRT.MethodsRectal dosimetry of 45 men who received SBRT within the PROMETHEUS trial was retrospectively examined, across two radiation therapy centres using the two RDD's. Men received a total dose (TD) of 19 or 20 Gy in two fractions followed by 46 Gy in 23 fractions. Centre 1 contributed 16 Rectafix and 10 SpaceOAR patients. Centre 2 contributed 19 Rectafix patients. Rectal dose volume histogram (DVH) data were recorded as a TD percentage at the following volume intervals; V1%, V2%, V5%, V10% and then 10% increments to V80%. As only one centre employed both RDD's, three sequential rectal dosimetry comparisons were performed; (1) centre 1 Rectafix versus centre 1 SpaceOAR; (2) centre 1 Rectafix versus centre 2 Rectafix and (3) centre 1+ centre 2 Rectafix versus centre 1 SpaceOAR.ResultsIn comparison (1) Rectafix demonstrated lower mean doses at 9 out of 11 measured intervals (P = 0.0012). Comparison (2) demonstrated a moderate difference with centre 2 plans producing slightly lower rectal doses (P = 0.013). Comparison (3) further demonstrated that Rectafix returned lower mean doses than SpaceOAR (P < 0.001). Although all dose levels were in favour of Rectafix, in absolute terms differences were small (2.6–9.0%).ConclusionsIn well‐selected prostate SBRT patients, Rectafix and SpaceOAR RDD's provide approximately equivalent rectal sparing.

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Stereotactic body radiotherapy for localized prostate cancer: Pooled analysis from a multi-institutional consortium of prospective phase II trials

Abstract: PSA relapse-free survival rates after SBRT compare favorably with other definitive treatments for low and intermediate risk patients. The current evidence supports consideration of SBRT among the therapeutic options for these patients.

Cited by 414 publications

References 21 publications

Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

A quantitative assessment of the consequences of allowing dose heterogeneity in prostate radiation therapy planning

Rectal protection in prostate stereotactic radiotherapy: a retrospective exploratory analysis of two rectal displacement devices

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