Prostate radiotherapy
Prostate stereotactic ablative body radiotherapy using a standard linear accelerator: Toxicity, biochemical, and pathological outcomes

https://doi.org/10.1016/j.radonc.2013.03.022Get rights and content

Abstract

Background and purpose

Biological dose escalation through stereotactic ablative radiotherapy (SABR) holds promise of improved patient convenience, system capacity and tumor control with decreased cost and side effects. The objectives are to report the toxicities, biochemical and pathologic outcomes of this prospective study.

Materials and methods

A phase I/II study was performed where low risk localized prostate cancer received SABR 35 Gy in 5 fractions, once weekly on standard linear accelerators. Common Terminology Criteria for Adverse Events v3.0 and Radiation Therapy Oncology Group late morbidity scores were used to assess acute and late toxicities, respectively. Biochemical control (BC) was defined by the Phoenix definition.

Results

As of May 2012, 84 patients have completed treatment with a median follow-up of 55 months (range 13–68 months). Median age was 67 years and median PSA was 5.3 ng/ml. The following toxicities were observed: acute grade 3+: 0% gastrointestinal (GI), 1% genitourinary (GU), 0% fatigue; late grade 3+: 1% GI, 1% GU. Ninety-six percent were biopsy negative post-treatment. The 5-year BC was 98%.

Conclusions

This novel technique employing standard linear accelerators to deliver an extreme hypofractionated schedule of radiotherapy is feasible, well tolerated and shows excellent pathologic and biochemical control.

Section snippets

Materials and methods

This study was approved by Sunnybrook Health Sciences Centre Research Ethics Board (REB 371-2006) and was registered on ClinicalTrials.gov (NCT01578902). Informed written consent was obtained from all patients participating in the study.

Results

The study was activated in October 2006. Due to acute financial issues in our clinical trials department in 2008, the last 16 patients could not be accrued. By July 2008, 95 patients were screened for the study. There were 3 screen failures (1 patient exceeded protocol defined girth limit of 40 cm; 2 patients had hip replacements) and 8 chose not to participate in the study. This left 84 patients accrued into the study.

Eight patients withdrew from the study before 5 years of follow-up with no

Discussion

In this prospective study, we showed that 5 weekly fractions (or treatments) of SABR were feasible and well tolerated in patients with localized prostate cancer. A summary of other prospective SABR protocols for prostate cancer is shown in Supplementary Table 1. A large multi-institutional retrospective series has been recently presented with similar results. [34] It should be emphasized that, while impossible to draw conclusions about relative tolerability across studies (due to varying

Conclusions

Stereotactic ablative body radiotherapy (SABR) for low-risk localized prostate cancer is feasible, well-tolerated and has excellent efficacy signals up to six years of follow-up. SABR allows safe biological dose escalation of prostate cancer with greater patient convenience, lower out-of-pocket and departmental costs and increased radiation therapy departmental treatment capacity. Further research is needed to refine the optimal SABR technique and machine requirements but ultimately SABR should

Conflict of interest statement

None of the authors has any conflict of interest with respect to this work.

Acknowledgements

This work was presented at the 2012 ASCO/ASTRO/AUA Genitourinary Cancer Symposium. Drs Loblaw and Cheung are co-primary investigators for this project. We would like to acknowledge Lori Holden and Angela Cesta for helping with patient support and data collection.

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