Figure 1.

The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) study flowchart and the number of individuals at each stage of the study.

¹ We only included those treated (class 1–2) at a single institution to ensure data consistency.

² Sixth (2007–2009) or Seventh (2010–2013) American Joint Committee on Cancer.

³ 60–70 Gy in 1.8–2 Gy/fraction, ±10% in dose.

⁴ Dose/fraction compatible with National Comprehensive Cancer Network non-small cell lung cancer guideline 2017 v8 (i.e., 25–34 Gy/1 fraction, or 45–60 Gy/3 fractions, or 48–50 Gy/4 fractions, or 50–55 Gy/5 fractions, or 60–70 Gy/8–10 fractions), ±10% in dose.

⁵Adenocarcinoma or non-adenocarcinoma.

⁶ Without missing information in the Taiwan cancer registry and death registry.