Survival of Tumours after Immunization against Oestrogens

Abstract

SOME tumours respond to a circulating hormone by growing at an optimum rate in an abundance of the hormone, or by regressing in its absence¹. Surgical procedures such as ovariectomy, adrenalectomy and hypophysectomy can curtail the growth of these tumours, including those which are susceptible to oestrogens². One such tumour, designated MT/W9A (ref. 3), grows readily in the intact female, regresses after ovariectomy, and grows at optimum rates after the administration of the synthetic oestrogen diethylstilboestrol. These observations, and the finding that antibodies to oestrogens can control the normal physiological responses to oestrogens in vivo, formed the basis for our study⁴. We have reported before that actively immunizing sheep against oestrogens by the administration of a conjugate of bovine serum albumin covalently linked to an oestradiol 17 β-hemisuccinate derivative (BSA-E²) resulted in the production of antisera which effectively neutralized the circulating levels of oestrogens; other workers have used a similar approach⁵. We have investigated whether antibodies to oestrogens might induce regression of an oestrogen sensitive tumour.