Estracyt, a conjugate of an
alkylating agent with an oestrogenic
sterol, was given in a dose of 420 mg daily to a group of 44 postmenopausal patients with very advanced
breast carcinoma. Thirty-eight of these were in relapse following
chemotherapy and 32 had evidence of distant
metastases. Seventeen patients had an objective response and marked or complete alleviation of symptoms, four others had a useful symptomatic response but no beneficial effect was observed in the remainder. Three who had shown no response to previous oestrogen
therapy also failed to respond to
Estracyt as did all nine patients with hepatic
metastases. Oestrogen receptor status and age within the postmenopausal group seemed to have no bearing on the result. Side-effects were minimal with
nausea in 18 patients but in only two did this necessitate withdrawal of the
drug. Bone marrow depression did not occur. Changes in
acute-phase reactant proteins suggested that part of the
Estracyt was de-esterified in the liver liberating oestrone but the low incidence of vaginal haemorrhage and the recalcification of bony
metastases suggested that on the whole
Estracyt behaves as an anti-oestrogen as well as an
antimitotic.