Stereotactic ablative radiotherapy for early stage lung cancer and lung metastases in a New Zealand population.

Aim: Stereotactic ablative radiotherapy (SABR) involves the delivery of high doses of precisely targeted radiation in a shorter time period than conventional radiotherapy. The aim of this study was to compare the outcomes of lung-based SABR in a New Zealand cohort to the global literature.

Methods: A single-institution retrospective analysis was performed on all patients who received lung-based SABR between May 2015 and September 2019 at Waikato Hospital, New Zealand. The study included both early stage lung cancer and lung oligometastases that measured less than 5cm.

Results: 102 patients received SABR to 116 lesions. Median follow-up was 19 months. The three-year rate of local control in the primary and metastatic cohorts was 85% and 82%, respectively. This reflects the three-year local control rate of 86% for primary lung cancer in the SPACE trial and the two-year local control rate of 81% for pulmonary oligometastases in a German study. Central primary lung cancer was associated with a higher risk of local recurrence (HR6.4 (1.3-31.5) p=0.02). The three-year progression-free survival rate in patients with early stage lung cancer and oligometastases was 56% and 26%, respectively. Māori patients with primary lung cancer had a significantly worse progression free survival (HR2.4 (1.1-5.1) p=0.03). There were no reported grade three toxicities.

Conclusion: The use of lung-based SABR in a typical radiotherapy setting in New Zealand mirrors global outcomes.