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.

Potential benefits and pitfalls of respiratory-gated radiotherapy in the treatment of thoracic malignancy.

AIM: Despite advances in radiotherapy delivery, the prognosis of lung cancer remains poor. Higher doses of radiation have been associated with improved outcomes but may result in higher toxicities. Respiratory gated radiotherapy (RGRT) has the potential to reduce pulmonary toxicity but there are significant limitations and pitfalls to its use. The aim of this article is to (i) describe the RGRT technique currently employed at Nepean and Westmead Hospitals; (ii) discuss the practical issues of implementing such a program; (iii) present the results of our RGRT program and (iv) review the potential uncertainties in using this technique and the methods we have used to overcome these. METHODS: A retrospective review of all patients who had a 4D-computed tomography (4D-CT) scan was undertaken. Records from treatment planning systems were used to assess the prospective gating program. RESULTS: Between September 2007 and June 2011, 53 patients at Nepean and 26 patients at Westmead Hospital underwent a 4D-CT. Between April and August 2011, 26 patients at Westmead Hospital underwent a prospective 4D-CT scan as treatment verification. Two of the 26 patients (7.7%) were found to have incomplete coverage of the planning target volume. Both patients underwent respiratory re-coaching, alleviating the need for replanning. CONCLUSION: RGRT may reduce doses to organs at risk with the potential for dose escalation. However its implementation requires significant staff training, treatment time and resources. Treatment verification with image guided radiation therapy are essential for safe delivery.

Minimal benefit of respiratory-gated radiation therapy in the management of thoracic malignancy.

BACKGROUND: Respiratory-gated radiotherapy (RGRT) is used in several centres around the world. However, there is continuing controversy regarding the benefit of this technique. The aims of this study are to quantify the dosimetric benefits and the potential predictive factors. METHODS: Thirty-four consecutive patients were planned using the RGRT and the Free Breathing (FB) approach and compared with regard to target volume coverage and normal tissue parameters. Potential predictive factors were also evaluated. RESULTS: Tumour coverage was similar 94.4% versus 95.5%. Use of RGRT was not associated with a significant reduction in spinal cord, oesophagus or cardiac dosimetric parameters. However, it did reduce the lung mean dose by 1.33 Gy (P < 0.001) and V20 by 2.2% (P < 0.001). Only superior/inferior displacement of >1 cm was predictive of a >5% reduction in lung V20 parameter, and these patients all had a gross tumour volume (GTV) of <100 cm(3). CONCLUSIONS: The dosimetric benefit of applying RGRT is small when applied in an unselected population of patients. Superior/inferior displacement of >1 cm for tumours with GTV less than 100 cm(3) may be used to select patients who may derive a >5% reduction in lung V20 parameters.

Deep inspiration breath hold technique reduces heart dose from radiotherapy for left-sided breast cancer.

INTRODUCTION: Adjuvant left breast radiotherapy (ALBR) for breast cancer can result in significant radiation dose to the heart. Current evidence suggests a dose-response relationship between the risk of cardiac morbidity and radiation dose to cardiac volumes. This study explores the potential benefit of utilising a deep inspiration breath hold (DIBH) technique to reduce cardiac doses. METHODS: Thirty patients with left-sided breast cancer underwent CT-simulation scans in free breathing (FB) and DIBH. Treatment plans were generated using a hybrid intensity-modulated radiation therapy technique with simultaneous integrated boost. A dosimetric comparison was made between the two techniques for the heart, left anterior descending coronary artery (LAD), left lung and contralateral breast. RESULTS: Compared with FB, DIBH resulted in a significant reduction in heart V30 (7.1 vs. 2.4%, P < 0.0001), mean heart dose (6.9 vs. 3.9 Gy, P < 0.001), maximum LAD planning risk volume (PRV) dose, (51.6 vs. 45.6 Gy, P = 0.0032) and the mean LAD PRV dose (31.7 vs. 21.9 Gy, P < 0.001). No significant difference was noted for lung V20, mean lung dose or mean dose to the contralateral breast. The DIBH plans demonstrated significantly larger total lung volumes (1126 vs. 2051 cc, P < 0.0001), smaller maximum heart depth (2.08 vs. 1.17 cm, P < 0.0001) and irradiated heart volume (36.9 vs. 12.1 cc, P < 0.0001). CONCLUSIONS: DIBH resulted in a significant reduction in radiation dose to the heart and LAD compared with an FB technique for ALBR. Ongoing research is required to determine optimal cardiac dose constraints and methods of predicting which patients will derive the most benefit from a DIBH technique.