ORIGINAL ARTICLE

Semi-quantitative scoring of potentially predictive markers for endocrine treatment of breast cancer: a comparison between whole sections and tissue microarrays

Katrine L Henriksen¹, Birgitte B Rasmussen², Anne E Lykkesfeldt¹, Susann Møller³, Bent Ejlertsen⁴ and Henning T Mouridsen^3,4

¹ Department of Tumor Endocrinology, Institute of Cancer Biology, Danish Cancer Society, Copenhagen Ø, Denmark
² Department of Pathology, Roskilde County Hospital, Roskilde, Denmark
³ Danish Breast Cancer Cooperative Group, Rigshospitalet, Copenhagen Ø, Denmark
⁴ Department of Oncology, Rigshospitalet, Copenhagen Ø, Denmark

Correspondence to:
Correspondence to:
Dr B B Rasmussen
Department of Pathology, Nordsjaellands Hospital, Hilleroed, Helsevej 2, DK-3400 Hilleroed, Denmark; bbr{at}noh.regionh.dk

Aim: To assess whether immunohistochemically stained tissue microarrays (TMA) of 2 mm cores from paraffin embedded tumour tissue may replace whole sections in semi-quantitative evaluation of selected potential markers for endocrine treatment.

Methods: Whole sections and 2 mm cores on TMA were used for immunohistochemical staining of potential markers for endocrine treatment. The Allred scoring system was used for the markers with nuclear localisation: the oestrogen receptor, the progesterone receptor, p27 and the oestrogen receptor co-regulator amplified in breast cancer 1 (AIB1). The Allred scoring system was also used for the non-nuclear markers Bcl-2, pS2 and cyclooxygenase 2 (COX-2); the membrane receptors HER-2, insulin-like growth factor I receptor (IGF-IR) and epidermal growth factor receptor were quantified according to the guidelines for the Herceptest.

Results: The data and statistical analyses showed that the semi-quantitative evaluation of oestrogen receptor, progesterone receptor, AIB1, COX-2, HER-2 and IGF-IR on TMA blocks was comparable with analysis on whole sections.

Conclusions: This study shows that semi-quantitative scoring of 2 mm cores on TMA is feasible for several potential markers for endocrine therapy. Considering the small size of many breast tumours, the speed and cost-effectiveness of immunohistochemistry on TMA compared with whole sections, and the importance of the expression level of the proteins, semi-quantitative scoring on TMA has great potential in both retrospective and prospective studies aiming at improving the prediction of response to endocrine treatment.

Abbreviations: AIB1, oestrogen receptor co-regulator amplified in breast cancer 1; COX-2, cyclooxygenase 2; EGFR, epidermal growth factor receptor; IHC, immunohistochemistry; IGF-IR, insulin-like growth factor I receptor; TMA, tissue microarray

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