("Hetenyi Geza" Fund of the Faculty of Medicine, University of Szeged)
The lack of oestrogen receptor, progesterone receptor and human epidermal growth factor
receptor-2 expression in breast cancer (BC) is the basis for the categorization of
the tumour as triple negative breast carcinoma (TNBC). The majority of TNBCs are aggressive
tumours with common metastases and decreased expression of markers that could help
in identifying the metastatic lesion as of mammary origin. Breast markers, such as
gross cystic disease fluid protein-15 (GCDPF-15), GATA binding protein 3 (GATA3),
mammaglobin (MGB) and SOX10, are not uniquely specific to BC. Our aim was to evaluate
trichorhinophalangeal syndrome type 1 (TRPS1) protein as a breast marker in a series
of cytokeratin-5-expressing TNBC, mostly corresponding to basal-like TNBCs, previously
characterized for the expression of other breast markers. One hundred seventeen TNBCs
in tissue microarrays were immunostained for TRPS1. The cut-off for positivity was
≥ 10%. The reproducibility of this classification was also assessed. TRPS1 positivity
was detected in 92/117 (79%) cases, and this exceeded the expression of previously
tested markers like SOX10 82 (70%), GATA3 11 (9%), MGB 10 (9%) and GCDFP-15 7 (6%).
Of the 25 TRPS1-negative cases, 11 were positive with SOX10, whereas 5 to 6 dual negatives
displayed positivity for the other makers. The evaluation showed substantial agreement.
Of the five markers compared, TRPS1 seems the most sensitive marker for the mammary
origin of CK5-expressing TNBCs. Cases that are negative are most often labelled with
SOX10, and the remainder may still demonstrate positivity for any of the 3 other markers.
TRPS1 has a place in breast marker panels.
