- Radiotherapy (RT) may confer a survival benefit in young women (aged 18-45 years) with early breast cancer consisting of all molecular subtypes except for triple-negative breast cancer (TNBC).
- Women with human epidermal growth factor receptor 2 (HER2)-enriched subtype appear to benefit the most.
Why this matters
- This study is the first to examine the effects of RT in young women by molecular subtype.
- Findings will allow clinicians to shape treatment decisions.
- Retrospective cohort of 23,148 young women diagnosed with stage T1-3N0-3M0 breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database over a median follow-up of 22 months.
- The main outcomes were OS and breast-cancer-specific survival (BCSS) by each molecular subtype: luminal-A (hormone receptor [HR]-positive/HER2−), luminal-B (HR+/HER2+), HER2-enriched (HR-/HER2+), and TNBC (HR−/HER2−).
- Funding: National Natural Science Foundation of China; other.
- Median age, 41 years; luminal-A subtype was most common (63.54%).
- RT (vs no RT) was associated with prolonged survival in women with HER2-enriched (HR, 0.295; P=.002), luminal-A (HR, 0.696; P=.006), and luminal-B (HR, 0.385; P=.005), but not TNBC.
- RT (vs no RT) was associated with prolonged survival in women with HER2-enriched (HR, 0.328; P=.004) but not luminal-A, luminal-B, and TNBC.
- Retrospective, observational design.
- Limited follow-up.