Is robotic arm stereotactic body radiation therapy ‘virtual high-dose rate brachytherapy’ effective for prostate cancer? An analysis of comparative effectiveness using published data

Abstract

High-dose rate brachytherapy (HDR-BT) monotherapy and robotic arm (i.e., CyberKnife) stereotactic body radiation therapy (SBRT) are emerging technologies that have become popular treatment options for prostate cancer. Proponents of both HDR-BT monotherapy and robotic arm SBRT claim that these modalities are as efficacious as intensity-modulated radiation therapy in treating prostate cancer. Moreover, proponents of robotic arm SBRT believe it is more effective than HDR-BT monotherapy because SBRT is non-invasive, touting it as ‘virtual HDR-BT.’ We perform a comparative effective analysis of the two technologies. The tumor control rates and toxicities of HDR-BT monotherapy and robotic arm SBRT are promising. However, at present, it would be inappropriate to state that HDR-BT monotherapy and robotic arm SBRT are as efficacious or effective as other treatment modalities for prostate cancer, which have stronger foundations of evidence. Studies reporting on these technologies have relatively short follow-up time, few patients and are largely retrospective.

Keywords:

• brachytherapy
• prostate cancer
• radiation therapy
• stereotactic body radiation therapy
• technology

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Erratum

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

Background

• Currently, the standard of care for prostate cancer patients receiving external beam radiation therapy is dose-escalated conventionally fractionated radiation therapy with intensity-modulated radiation therapy (IMRT).

• High-dose rate brachytherapy (HDR-BT) monotherapy and robotic arm (i.e., CyberKnife) stereotactic body radiation therapy (SBRT) are emerging technologies that have become popular treatment options for prostate cancer.

• Proponents of both HDR-BT monotherapy and robotic arm SBRT claim that these modalities are as efficacious as IMRT in treating prostate cancer. Moreover, proponents of robotic arm SBRT believe it is more effective than HDR-BT monotherapy because SBRT is non-invasive, touting it ‘virtual HDR-BT.’

Efficacy and effectiveness of HDR-BT and robotic arm SBRT

• The tumor control rates and toxicities of HDR-BT monotherapy and robotic arm SBRT are promising.

• – For robotic arm SBRT, freedom from biochemical failure rates for low-, intermediate- and high-risk patients have generally been ≥90% at up to 5 years.

• – For HDR-BT monotherapy, freedom from biochemical failure rates for low-, intermediate- and high-risk patients have generally been ≥85% at up to 5 years.

• – For both robotic arm SBRT and HDR-BT monotherapy, less than 5% of patients had grade 3–4 gastrointestinal or genitourinary toxicity.

• – Compared with low-dose rate-BT and external beam radiation therapy, robotic arm SBRT and HDR-BT monotherapy studies have a relatively short follow-up time, few patients and are mostly retrospective.

• There are several important factors that may influence practitioners to select HDR-BT monotherapy over robotic arm SBRT or vice versa, including the longer duration of each RT fraction of SBRT (up to an hour), the dose spillage to adjacent organs with SBRT, and the risk of infection or bleeding with HDR-BT.

• To date, it would be inappropriate to state that HDR-BT monotherapy and robotic arm SBRT are as efficacious or effective as other treatment modalities for prostate cancer, which have stronger foundations of evidence.

Efficiency of HDR-BT monotherapy and robotic arm SBRT

• The total cost of an IMRT schedule has been estimated at US$ 29,356.

• Changing to a hypofractionated schedule (e.g., with robotic arm SBRT or HDR-BT monotherapy) may decrease the number of work-hours and overall cost of treating each patient.

• – Robotic arm SBRT has been estimated to cost between US$ 19,275 and US$ 22,152.

• – HDR-BT monotherapy has also been shown to be more cost-effective than IMRT, at US$ 17,514.

• CER will provide a framework for evaluating advanced RT technologies by comparing the benefit and harm of available diagnostic, prognostic and therapeutic options to optimize the risk–benefit ratio and improve cost–effectiveness.

Notes