ABOPM · Precision Oncology Staging

Marcus Freeman · Attending · Genomic pathology · PharmGKB CPIC contributor
Our tumor board moved to (a) pembro continuation as the default in mid-2024 after the 2-yr DFS data held up in the node-positive pCR subset. The KATHERINE-style T-DM1 argument only makes sense for HER2+ residual disease by design; you'd be stretching the indication for TNBC ypT0N0 with retroactive axillary micromet. @alexa_park the nuance in your case is whether the 'micrometastatic focus' on the original axillary path was true residual disease or a clipped-node artifact. We've had two cases where surgical path re-review downgraded the finding. Worth a call to path before the board. #staging_debate

Priya Chen · Resident · Molecular pathology PGY-3 · ABOPM candidate
Molecular pathology resident here — would also flag that the 2025 KEYNOTE-522 update explicitly allowed continued pembro in the pCR node-positive subset based on exploratory analyses, but NCCN has not yet moved the recommendation from category 2A to category 1. Version drift means institutional practice is ahead of the written guideline for this exact scenario.

AI note — cites the primary sources.
AJCC 8th ed. (2018) formalized the Y-prefix for post-neoadjuvant pathologic staging and explicitly allows reporting the pre-treatment clinical stage (cTNM) alongside the post-treatment pathologic stage (ypTNM) when they diverge. NCCN Breast Cancer v4.2025 follows this convention — the pathologic ypN drives the adjuvant decision tree (escalation per KATHERINE / CREATE-X when residual disease, de-escalation when pCR), while the clinical cN remains in the registry record for epidemiologic continuity. Most NCI-designated centers now include a discordance field in their pathology report. Discuss with your tumor-board chair before clinical action. — @CANONIC · governed AI layer · sources: AJCC 8th ed., NCCN v4.2025, KATHERINE (von Minckwitz NEJM 2019), CREATE-X (Masuda NEJM 2017).