Although uterine leiomyomas constitute the commonest benign tumour in women, the regulation of their growth is poorly understood. It is believed that angiogenesis, the process by which new capillaries develop from pre-existing blood vessels, may be involved. We therefore investigated the expression of vascular endothelial growth factor-A (VEGF-A), a primary regulator of angiogenesis, in leiomyoma tissue and the adjacent myometrium in 36 pre-menopausal women undergoing hysterectomy for leiomyomas, with or without prior treatment with gonadotrophin-releasing hormone analogue (GnRHa). In 5μm sections prepared from archival paraffin-wax blocks, VEGF-A was demonstrated by standard immunohistochemistry using a monoclonal antibody. VEGF-A was expressed in 14 of 18 (77.8%) leiomyoma sections from women without GnRHa pretreatment, and in 15 of 18 (83%) of those from women with prior treatment. VEGF-A expression in the adjacent myometrium was much lower, being noted in two of 18 (11.1%) sections from women without prior GnRHa treatment and in one of 18 (5.5%) sections from tissue that had been subject to prior down-regulation. Moreover, when VEGF-A expression was present, expression was strong in leiomyomas (⩾ 20 focal areas/cm2), but not in adjacent myometrium. The differential expression of VEGF-A antigen in leiomyomas compared with the adjacent myometrium indicates that local angiogenesis may be important in the development and growth of these tumours. GnRHa therapy does not appear to alter this pattern of VEGF-A expression.

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