- Radiation therapy (RT) was not associated with overall increased risk for second cancer (SC).
- SC risk was increased with RT-only, but not with RT after radical prostatectomy (RP+RT).
Why this matters
- Previous reports have provided conflicting results.
- 10-y SC incidence was 15.9%, 13.2%, and 10.5% for RT-only, RP+RT, and RP-only (P<.0001).
- Incidence of colon cancer was 1.7%, 2.0%, and 1.1%, respectively.
- Rectal cancer occurred in 1.1%, 0.3%, and 0.6%.
- Bladder cancer occurred in 2.7%, 1.5%, and 1.1%.
- Nonmelanoma skin cancer (NMSC) occurred in 2.1%, 1.6%, and 1.2%.
- Incidence of lung cancer was 2.2% with RT-only and 1.2% with RP regardless of postoperative RT.
- Age, T- and N-category and treatment were predictors for SC development.
- RP+RT and RT-only patients were at higher risk for colon cancer (HR, 1.903 and 1.326; P=.0035).
- Risk for rectal cancer increased with RT-only (HR, 1.751; P=.0077), and decreased with RP+RT (HR, 0.638; P=.0077).
- RT-only patients were at high risk for lung cancer (HR, 1.733; P=.0011).
- RT-only and RP+RT were associated with increased risk for bladder cancer (HR, 2.098 and 1.601; P<.001) and NMSC (HR, 1.658 and 1.305; P<.0020).
- Retrospective study (N=19,538).
- Funding: None.
- Small number of events in some subgroups.