After neoadjuvant pembrolizumab in TNBC, report the pattern of residual disease and each node's response

Design

Retrospective single-centre cohort

Population

203 women with early TNBC after neoadjuvant chemotherapy plus pembrolizumab

Primary outcome

Pathological response patterns in breast and nodes; recurrence

Effect

pCR 63.1%; residual disease solitary in 51.4%; mixed nodal response 7.4%

This Korean real-world study, published 24 September in Histopathology, reviewed baseline biopsies and surgical specimens from 203 women with early triple-negative breast cancer treated with neoadjuvant chemotherapy plus pembrolizumab.

Pathological complete response was achieved in 63.1%. Higher grade, more tumour-infiltrating lymphocytes and higher Ki-67 were independently associated with pCR. Where disease remained, it was most often a single confined focus (51.4%). Fibrotic tumour beds were more common without pCR, stromal elastosis with pCR. Nodal responses varied: complete nodal response in 23.6%, no response in 8.4% and mixed response in 7.4%. Recurrence was more frequent without pCR and with low TILs, multifocal baseline tumours, higher clinical T stage, rare histological subtypes and residual nodal disease.

With chemoimmunotherapy now standard for early TNBC, more specimens will show complete or near-complete response. A binary pCR and ypN stage misses information oncologists use: residual pattern, mixed nodal response and baseline TILs.

• Record baseline stromal TILs on the diagnostic core biopsy of every TNBC.
• Describe residual disease as a solitary focus or scattered, and report residual cancer burden.
• Report nodal response node by node, including mixed responses, not just ypN.
• Sample the tumour bed generously when it looks fibrotic, as fibrosis was commoner with residual disease.

Why it matters

Pathology reports are the source of the risk information oncologists now use to decide adjuvant treatment.

Don't overread it

Single-centre, retrospective; the recurrence associations have not been validated as prognostic tools.

The statistics, in plain English

A pCR rate of 63.1% means about two in three women had no residual invasive cancer. The associations with recurrence are from one centre's cohort and are not independent predictive models.

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