Prostaglandins, steroids and human mammary cancer.

PGE2 and PGF2 alpha secretion in vitro were measured from tissues of patients with breast tumours and examined in relation to oestrogen receptor status. Prostaglandin secretion was significantly greater from malignant breast tumours than from 'normal' breast tissue or benign tumours. Synthesis of PGE2 by oestrogen-positive and malignant tumours was significantly higher than by oestrogen-negative tumours, suggesting a correlation between prostaglandin E2 and receptor status. Synthesis of PGF2 alpha by the malignant tumour tissues also occurred, but only at relatively low levels and with no significant difference between oestrogen-positive and negative tissues. Exogenous oestrogen in vitro had a significant stimulatory effect on both PGE2 and PGF2 alpha secretion by oestrogen-positive malignant tumour tissues but did not influence oestrogen-negative tumour tissues. Progesterone, on the other hand, had no statistically significant effect on PG secretion by either type of tumour tissue, although the increased levels of PGE2 secreted by oestrogen-positive tumour tissue in the presence of progesterone are unlikely to have arisen by chance. The results support the concept of steroidal influence on excess production of prostaglandins by human malignant breast tumour tissues.