ESTROGEN-RECEPTOR ANALYSIS OF PARAFFIN SECTIONS AND CYTOSOL SAMPLES OF PRIMARY BREAST-CANCER IN RELATION TO OUTCOME AFTER ADJUVANT TAMOXIFEN TREATMENT

The aim of the present study was to compare oestrogen receptor (ER) an alysis results obtained in cytosols of frozen breast cancer tissue (us ing biochemical assay) with those obtained in paraffin-embedded tissue (using immunoperoxidase staining with monoclonal antibodies (DAKO-ER, 1D5), and an ER positivity cut-off level of > 10% stained nuclei). In 86% (84/98) of the samples the same ER status (28 negative and 56 pos itive) was obtained with both procedures, In eight cases, the paraffin section was ER positive but the corresponding cytosol sample ER negat ive, whereas six cases showed the opposite pattern. The ER positive su bgroup manifested better outcome after adjuvant treatment than the ER negative subgroup (p = 0.003 (cytosol), and p = 0.004 (paraffin)), As compared with the percentage of stained nuclei, staining intensity yie lded no additional information, Although the results of ER analysis of paraffin-embedded material seem promising, it is too early to prefer it to frozen tissue, though this would be useful when no frozen tissue is available.