NUCLEAR AREAS IN BREAST-CANCER - RELATIONSHIP WITH ESTROGEN AND PROGESTERONE-RECEPTOR EXPRESSION

The relationship between nuclear area and the expression of estrogen ( ER) and progesterone receptors (PR) was evaluated in a series of 66 br east carcinomas (50 primaries, 16 metachronous recurrences). Nuclear m easurements were directly performed on touch imprints previously react ed for ER and PR by the immunocytochemical method. Nuclei expressing E R or PR were found to be smaller than negative ones. Moreover, area va lues of PR+ nuclei overlapped with those of ER+ ones. The pattern of r eceptor expression co-existence was observed to be closely related to nuclear dimensions, since a significant increase in mean nuclear areas was detected in cells from ER-/PR- tumours, as compared with cells fr om ER+/PR+, ER+/PR- and ER-/PR+ sub-groups. Nuclear area values were a lso determined in both steroid receptor-positive and steroid receptor- negative neoplastic cells co-existing in the same breast carcinoma. No significant differences in nuclear area values were found between rec eptor-positive and receptor-negative neoplastic cells in tumours featu ring a positive status for at least one of the steroid receptors (ER+/ PR+, ER+/PR- or ER-/PR+). On the contrary, in breast carcinomas charac terized by a negative steroid receptor status (ER-/PR-), receptor-nega tive neoplastic nuclei were significantly larger than receptor-positiv e ones. It is suggested that heterogeneous steroid receptor expression may be caused by a completely different pathogenetic mechanism in rec eptor-positive and receptor-negative breast carcinomas.