Rapid fire.

That’s the pace of practice-changing breast cancer publications this week, including the full manuscript of the RAPID trial. We learned at the same San Antonio breast conference that, where B39 failed us, this study established non-inferior local recurrence rates with partial versus whole breast external beam radiation techniques. The pub confirms no real difference in in-breast recurrence rates: 3% after partial versus 2·8% after whole breast radiation at 8 years. One big (the?) reason statistical non-inferiority was established despite half the enrollees as B-39 was a more liberal a priori threshold for the upper boundary of the confidence interval (2.0). So the fact it was actually higher in RAPID (1.9) than in B-39 (1.6) was no big deal. For what it’s worth, acute grade 2+ toxicity was less after partial (28%) than whole (45%) breast radiation, while late grade 2+ toxicity was more (32% versus 13%, respectively). Finally, there was an absolute increase in fair or poor cosmesis of 10-18% after partial breast at all time points. TBL: All available evidence shows no meaningful forfeit in local control when radiating just part of the breast, though accelerating it to complete in just 5 days can likely result in worse cosmetic outcomes. | Whelan, Lancet 2019


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