SABCS 2018 — Accelerated PBI, WBI not quite equal for ipsilateral tumor recurrence


  • Tara Haelle
  • Univadis
El acceso al contenido completo es sólo para profesionales sanitarios registrados. El acceso al contenido completo es sólo para profesionales sanitarios registrados.

Takeaway

  • Accelerated partial breast irradiation (PBI) after lumpectomy is marginally less effective than whole-breast irradiation (WBI) for preventing ipsilateral breast tumor recurrence (IBTR), according to data from the phase 3 NSABP B-39/RTOG 0413 trial.

Why this matters

  • Given low absolute rates of recurrence and similar OS, women with early-stage breast cancer may cautiously consider accelerated PBI.

Study design

  • 4216 women with a recent lumpectomy with histologically free margins and 0-3 positive axillary nodes were randomly assigned to PBI for 5-10 days (n= 2107) or WBI for 5-6 weeks (n= 2109).
  • Funding: NIH.
  • Dr. Vicini is a research advisor for ImpediMed.

Key results

  • Median follow-up, 10.2 years.
  • 10-year IBTR rate was higher with accelerated PBI vs WBI (4.6% vs 3.9%; HR, 1.22; 90% CI, 0.94-1.58), with an absolute difference of 0.7%.
    • Accelerated PBI missed primary endpoint for noninferiority, defined as 90% CI between 0.667 and 1.5 for HR.
  • 10-year recurrence-free survival was lower with accelerated PBI (91.9% vs 93.4%; HR, 1.33; P=.02).
  • Accelerated PBI and WBI were similar with respect to:
    • Distant disease-free interval at 10 years (96.7% vs 97.1%; P=.15).
    • OS (90.6% vs 91.3%; P=.35).
  • Accelerated PBI yielded more grade 3 (9.6% vs 7.1%) and grade 4-5 (0.5% vs 0.3%) toxicity.

Limitations 

  • QoL and cosmetic data not captured.