- Patients with initial primary lung cancer (IPLC) who received radiotherapy were significantly less likely to develop metachronous second primary lung cancer (SPLC) than those who did not receive radiotherapy.
Why this matters
- Prior studies suggest radiation exposure during radiotherapy is associated with an increased risk of lung cancer.
- 36,156 patients with IPLC between 2004-2007 from the Surveillance, Epidemiology, and End Results database who received radiotherapy (n=11,657) or not (control; n=24,499).
- Funding: None disclosed.
- Radiotherapy group had lower rates of metachronous SPLC at 5 years (2.3% vs 4.45%; HR, 0.49, 95% CI, 0.43-0.57).
- Median survival was significantly better in the radiotherapy group (69.6 months vs 54 months; P<.001>
- Radiotherapy patients with stage I disease had the highest risk of metachronous SPLC (0.98% at 1 year; 3.83% at year 5) and stag IV patients had the lowest risk (0.29% at 1 year; 0.72% at year 5).
- After propensity matching, the radiotherapy group had a lower 5-year cumulative incidence of metachronous SPLC (2.5% vs 3.3%; HR, 0.72; 95% CI, 0.55-0.95).
- Survival following development of metachronous SPLC was similar between radiotherapy and control groups.
- Retrospective study.