Collaborative implementation of stereotactic ablative body radiotherapy: A model for the safe implementation of complex radiotherapy techniques in Australia

INTRODUCTION

Stereotactic ablative radiotherapy (SABR) for lung cancer is a modality of treatment that has improved outcomes for lung cancer patients. However, radiotherapy for lung cancer is underutilized and fewer than half of elderly patients with non-small cell lung cancer (NSCLC) receive active treatment. The purpose of this study is to report on a collaboration in implementing an NSCLC SABR (stereotactic ablative body radiation) program safely, efficiently, and uniformly across several centers, including regional sites. The first aim of this paper is to detail the collaboration and implementation that started in 2013 and is ongoing. The second aim of this paper is to document early toxicities and quality of life outcomes.

METHOD

A tripartite approach was used to develop the protocol and networks required for the implementation of SABR across multiple sites in NSW. Departments starting the programmes were supported and physics credentialing with central site submission was required before commencing the treatment. Additional ongoing support was available via an email discussion group involving all members of the collaboration.

RESULTS

Between July 22, 2013 and February 22, 2016, 41 patients were enrolled with 34 patients in active follow up. The toxicity profile so far is similar to those of published studies with no appreciable effect on quality of life outcomes.

CONCLUSION

The collaboration formed an effective framework in facilitating the implementation of SABR across several sites in NSW and could be used as a model for the safe and uniform implementation of new technologies in Australia.

Strategies for prediction and mitigation of radiation-induced liver toxicity

Although well described in the 1960s, liver toxicity secondary to radiation therapy, commonly known as radiation-induced liver disease (RILD), remains a major challenge. RILD encompasses two distinct clinical entities, a 'classic' form, composed of anicteric hepatomegaly, ascites and elevated alkaline phosphatase; and a 'non-classic' form, with liver transaminases elevated to more than five times the reference value, or worsening of liver metabolic function represented as an increase of 2 or more points in the Child-Pugh score classification. The risk of occurrence of RILD has historically limited the applicability of radiation for the treatment of liver malignancies. With the development of 3D conformal radiation therapy, which allowed for partial organ irradiation based on computed tomography treatment planning, there has been a resurgence of interest in the use of liver irradiation. Since then, a large body of evidence regarding the liver tolerance to conventionally fractionated radiation has been produced, but severe liver toxicities has continued to be reported. More recently, improvements in diagnostic imaging, radiation treatment planning technology and delivery systems have prompted the development of stereotactic body radiotherapy (SBRT), by which high doses of radiation can be delivered with high target accuracy and a steep dose gradient at the tumor - normal tissue interface, offering an opportunity of decreasing toxicity rates while improving tumor control. Here, we present an overview of the role SBRT has played in the management of liver tumors, addressing the challenges and opportunities to reduce the incidence of RILD, such as adaptive approaches and machine-learning-based predictive models.

Characterization and evaluation of 2.5 MV electronic portal imaging for accurate localization of intra- and extracranial stereotactic radiosurgery

2.5 MV electronic portal imaging, available on Varian TrueBeam machines, was characterized using various phantoms in this study. Its low-contrast detectability, spatial resolution, and contrast-to-noise ratio (CNR) were compared with those of conventional 6 MV and kV planar imaging. Scatter effect in large patient body was simulated by adding solid water slabs along the beam path. The 2.5 MV imaging mode was also evaluated using clinically acquired images from 24 patients for the sites of brain, head and neck, lung, and abdomen. With respect to 6 MV, the 2.5 MV achieved higher contrast and preserved sharpness on bony structures with only half of the imaging dose. The quality of 2.5 MV imaging was comparable to that of kV imaging when the lateral separation of patient was greater than 38 cm, while the kV image quality degraded rapidly as patient separation increased. Based on the results of patient images, 2.5 MV imaging was better for cranial and extracranial SRS than the 6 MV imaging.

Guidelines for safe practice of stereotactic body (ablative) radiation therapy

The uptake of stereotactic ablative body radiation therapy (SABR)/stereotactic body radiation therapy (SBRT) worldwide has been rapid. The Australian and New Zealand Faculty of Radiation Oncology (FRO) assembled an expert panel of radiation oncologists, radiation oncology medical physicists and radiation therapists to establish guidelines for safe practice of SABR. Draft guidelines were reviewed by a number of international experts in the field and then distributed through the membership of the FRO. Members of the Australian Institute of Radiography and the Australasian College of Physical Scientists and Engineers in Medicine were also asked to comment on the draft. Evidence-based recommendations (where applicable) address aspects of departmental staffing, procedures and equipment, quality assurance measures, as well as organisational considerations for delivery of SABR treatments. Central to the guidelines is a set of key recommendations for departments undertaking SABR. These guidelines were developed collaboratively to provide an educational guide and reference for radiation therapy service providers to ensure appropriate care of patients receiving SABR.

The early result of whole pelvic radiotherapy and stereotactic body radiotherapy boost for high-risk localized prostate cancer

Purpose: The rationale for hypofractionated radiotherapy in the treatment of prostate cancer is based on the modern understanding of radiobiology and advances in stereotactic body radiotherapy (SBRT) techniques. Whole-pelvis irradiation combined with SBRT boost for high-risk prostate cancer might escalate biologically effective dose without increasing toxicity. Here, we report our 4-year results of SBRT boost for high-risk localized prostate cancer.

Methods and Materials: From October 2009 to August 2012, 41 patients newly diagnosed, high-risk or very high-risk (NCCN definition) localized prostate cancer were treated with whole-pelvis irradiation and SBRT boost. The whole pelvis dose was 45 Gy (25 fractions of 1.8 Gy). The SBRT boost dose was 21 Gy (three fractions of 7 Gy). Ninety percent of these patients received hormone therapy. The toxicities of gastrointestinal (GI) and genitourinary (GU) tracts were scored by Common Toxicity Criteria Adverse Effect (CTCAE v3.0). Biochemical failure was defined by Phoenix definition.

Results: Median follow-up was 42 months. Mean PSA before treatment was 44.18 ng/ml. Mean PSA level at 3, 6, 12, 18, and 24 months was 0.94, 0.44, 0.13, 0.12, and 0.05 ng/ml, respectively. The estimated 4-year biochemical failure-free survival was 91.9%. Three biochemical failures were observed. GI and GU tract toxicities were minimal. No grade 3 acute GU or GI toxicity was noted. During radiation therapy, 27% of the patient had grade 2 acute GU toxicity and 12% had grade 2 acute GI toxicity. At 3 months, most toxicity scores had returned to baseline. At the last follow-up, there was no grade 3 late GU or GI toxicity.

Conclusions: Whole-pelvis irradiation combined with SBRT boost for high-risk localized prostate cancer is feasible with minimal toxicity and encouraging biochemical failure-free survival. Continued accrual and follow-up would be necessary to confirm the biochemical control rate and the toxicity profiles.