Stephen Ramey: NSABP B-51/RTOG 1304 presented at NRG2024

Stephen Ramey, Radiation oncologist in Savannah, Georgia, shared a post on X/Twitter:

“NSABP B-51/RTOG 1304 presented at NRG2024
cN1 breast cancer pts who converted to ypN0 with neoadj chemo
no SS DFS or OS benefit to WBRT + RNI or CW RT inc RNI (superiority design)
thread below includes details from presentation

PEP was invasive breast cancer recurrence free interval (IBCRFI)
80% power to detect 4.6% abs improvement at 5y
Eligible cT1-3N1, SLNB or ALND, ypN0
Mastectomy or lumpectomy 1602 pts in OS analysis w/ median f/u 59.5 mo

~60% T2
~22% triple neg
~21% ER+ and H2-
>50% H2+
58% lumpectomy and 42% mastectomy
55% SLNB and 45%ALND
~78% pCR in breast as well

No SS diff in IBCRFI, isolate LRF, Distant Mets
Numerically more local/regional failures w/o RNI but abs numbers small (1.4% vs 0.5%) p = 0.088, HR 0.37

Also no SS diff in OS or DFS
~ 88% DFS and 94% OS in both arms

Subset analyses (with all caveats of these)
RNI slightly favored in ER+ and H2- and No RNI slightly favored in triple negative
Severe tox relatively low in both arms

Conclusions and acknowledgments

Source: Stephen Ramey/X