IS STEROID-RECEPTOR PROFILE IN CONTRALATERAL BREAST-CANCER A MARKER OF INDEPENDENCE OF THE CORRESPONDING PRIMARY TUMOR

We compared oestrogen receptor (ER) and progesterone receptor (PgR) pr ofiles between primary and corresponding contralateral breast cancer ( CBC) to investigate whether CBC should be considered relapse of a prim ary or as a feature of the multicentric origin of breast cancer. We ad justed for patient age, menopausal status, histology and adjuvant ther apy. In spite of the general application of a cut-off value to dichoto mise ER and PgR, we considered them as continuous variables. Moreover, we considered as synchronous cancers only simultaneously occurring le sions. For 399 patients, ER and PgR receptor levels in primary and CBC did not differ significantly, but were significantly correlated withi n the same patient. The correlation was higher for synchronous than fo r metachronous lesions when considering ER, but not PgR. The correlati on between ER and PgR levels in the same tumour (primary or CBC) appea red stronger than the correlation of either receptor type (ER or PgR) between primary and CBC. Age, histology and adjuvant treatment affecte d ER concentration, whereas age, menopausal status and histology affec ted PgR concentration. The analysis indicated that primary and CBC ten d to be characterised by a similar steroid receptor profile. The findi ng may support the hypothesis of CBC as a second primary arising in a common predisposing milieu, rather than a primary-dependent contralate ral lesion. In this light, the clinical management of patients with a bilateral breast cancer should be similar to that of a unilateral brea st cancer. (C) 1998 Elsevier Science Ltd. All rights reserved.