Partly.

Just when you think we need longer follow-up of partial breast irradiation (PBI) data, we have 20 year results from a single-center, phase 3 Hungarian trial of partial versus whole breast radiation (WBRT). Over 250 women with early stage breast cancer (2 cm or less, N0, grade 1-2, no pure DCIS, no extensive intraductal component) were randomized to PBI or WBRT after lumpectomy. PBI was either APBI using a multicatheter HDR technique (5.2 Gy BID x 7, used in 2/3) or conventionally fractionated PBI using an electron field to deliver 50 Gy in 25 fractions (used in 1/3). The trial ended up closing earlier than planned as patients began enrolling on the GEC-ESTRO APBI trial. So, existing enrollment was powered to detect a 10% absolute difference in 5-year IBTR. After over 18 years of median follow-up, the rate of IBTR as a first event was 7.8% with PBI and 6.2% with WBRT. The 20-year actuarial rate of local recurrence was 9.6 vs 7.9% (not exactly the <1% difference seen in B-39 and RAPID). TBL: Long-term results of an early PBI trial don’t suggest any glaring differences in IBTR between whole and partial breast radiation. | Polgar, Int J Radiat Oncol Biol Phys 2020