Mechanisms of hormone-mediated carcinogenesis of the ovary

Abstract

Experimental ovarian carcinogenesis has been investigated in inbred and hybrid strains of mice and induced by a diversity of mechanisms including X-irradiation, oocytotoxic xenobiotic chemicals, ovarian grafting to ectopic or orthotopic sites, neonatal thymectomy, mutant genes reducing germ cell populations, and aging. Disruptions in the function of graafian follicles by a variety of mechanisms results in a spectrum of ovarian proliferative lesions, including tumors. The findings in mutant and genetically engineered mice support the concept of a secondary (hormonally mediated) mechanism of ovarian tumorigenesis in mice associated with sterility. Multiple pathogenic factors that either destroy or diminish the numbers of graafian follicles in the ovary result in decreased sex hormone secretion, especially estradiol-17β, leading to a compensatory overproduction of pituitary gonadotrophins, particularly LH, which places the mouse ovary at an increased risk for developing tumors in chronic studies. The intense proliferation of ovarian surface epithelium and stromal (interstitial) cells with the development of unique tubular adenomas in response to sterility does not appear to have a counterpart in the ovaries of adult human females.