Feasible Optimization of Stereotactic Ablative Radiotherapy Dose by Tumor Size for Stage I Non-small-cell Lung Cancer

作者：Lee Sumin; Song Si Yeol^*; Kim Su Ssan; Choi Wonsik; Je Hyoung Uk; Back Geum Mun; Cho Byungchul; Jeong Seong Yun; Choi Eun Kyung

来源：Clinical Lung Cancer, 2018, 19(2): E253-E261.

DOI：10.1016/j.cllc.2017.11.001

• Dose escalation
• Local control
• Non-small-cell lung cancer
• Stage I
• Stereotactic body radiotherapy

The effect of dose escalation of stereotactic ablative radiotherapy, from 48 Gy in 4 fractions (biologically effective dose [BED] = 106 Gy(10)) to 60 Gy in 4 fractions (BED = 150 Gy(10)), was evaluated for NSCLC. Tumors <= 2 cm had no local recurrence regardless of dose, whereas for tumors > 2 cm, approximately 150 Gy(10) BED showed significantly higher local control.
Introduction: The purpose of this study was to assess the effect of dose escalation of stereotactic ablative radiotherapy (SABR) by investigating the long-term clinical outcomes of SABR for stage I nonesmall-cell lung cancer (NSCLC). Methods: A retrospective analysis was performed on a total of 169 patients with 178 lesions of stage I NSCLC treated with SABR at a single institution from June 2000 to May 2015. The standard dose scheme for SABR was 48 Gy in 4 fractions during the early period of the analysis, but it was escalated to 60 Gy in 4 fractions from June 2009. All failures were recorded over the follow-up period. Results: Median follow-up time was 32 months. The 5-year overall survival rate was 46.7%, and the actuarial local control rate was 79.3%. Tumor size was an independent prognostic factor for survival. No relapse occurred in tumors <= 2 cm irrespective of SABR dose. Escalated doses of approximately 60 Gy in 4 fractions (biologically effective dose [BED] = 150 Gy(10)) achieved higher local control compared with 48 Gy in 4 fractions (BED = 106 Gy(10)) (76.2% vs. 60.6%) at 5-year follow-up (P =. 022) in tumors > 2 cm. There were no differences in treatment-related toxicities between the dose groups. Major failures consisted of distant metastasis to another lung parenchyma. Conclusion: SABR provides satisfactory long-term local control and high overall survival in medically inoperable stage I NSCLC. Tumors <= 2 cm had no local recurrence regardless of dose; whereas for tumors > 2 cm, an escalated BED of approximately 150 Gy(10) provided significantly higher local tumor control.

• 出版日期2018-3