Modulatory effects of oestrogen on immunological responsiveness. II. Suppression of tumour-associated immunity in patients with prostatic cancer.

The effect of oestrogen (diethylstilboesterol diphosphate, DES-P) on immunity to tumour-associated antigens in patients with prostatic cancer was evaluated by leucocyte adherence inhibition, a suggested in vitro correlate of cellular immunity. Significant (P smaller than 0.05) suppression of immunity to malignant prostate was observed in thirty out of thirty-one patients following pre-incubation of their leucocytes with therapeutically significant levels of DES-P. Suppression of tumour-associated immunity by exogenous oestrogen provides further evidence to earlier studies demonstrating oestrogenic suppression of non-specific cellular responsiveness evaluated by mitogen-induced lymphocytic blastogenesis, and for concern over the efficacy of oestrogenic therapy and its adverse effect in the treatment of patients with hormone-dependent tumours and responsive diseases. The reduced efficiency of immunosurveillance of tumours and underlying infectious agents may contribute to the exacerbation of disease. While speculative, these observations may also be relevant to the possible assocition between uterine cancer and prolonged administration of DES and the development of vaginal tumours in offspring found in association with maternal ingestion during pregnancy.