Almost 70% of all breast cancer is estrogen-responsive. Aromatase (the enzyme that converts androgens to estrogens) expressed in fat tissue and fibroblasts, is primarily responsible for the estrogen production that stimulates breast tumors, especially in post-menopausal women. Several studies (including two recent studies that I co-authored (Fan et al. 2007) and two studies co-authored by Novartis/Syngenta-funded scientist John Giesy) (Sanderson et al. 2001; Sanderson et al. 2000) have shown that atrazine induces aromatase via the promoter that regulates the gene in fat, fibroblasts and the gonads (Agarwal et al. 1996; Carlone and Richards 1997; Chang et al. 2005; Fitzpatrick and Richards 1994; Harada et al. 1993; Hinshelwood et al. 2003; Michael et al. 1995; Pancharatnam et al. 2004; Young and McPhaul 1997; Zhou et al. 1996) and atrazine’s effects on aromatase occur in the ppb range (Fan et al. 2007). Given that Novartis (formed from the union of Ciba and Astrazeneca) and Astrazeneca both market aromatase inhibitors (letrozole and anstrazole, respectively), proclaimed to be 1000 times better at treating post-menopausal breast cancer than current treatments, how does Syngenta (the ag-chemical company born out of Novartis) justify its continued sell of the aromatase inducer (atrazine)? I.e. given these contradictory data, how does Syngenta justify its position that atrazine exposure has no impact on breast cancer rates or on the efficacy of Novartis and Astrazeneca’s aromatase-inhibiting breast cancer treatments?

References:

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Blumenstyk G. 2003 The price of research: A Berkeley scientist says a corporate sponsor tried to bury his unwelcome findings and then buy his silence. Chronicle of Higher Education;A26-A29.

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Fan W, Yanase T, Morinaga H, Gondo S, Okabe T, Nomura M, Komatsu T, Morohashi K-I, Hayes T, Takayanagi R and others. 2007. Atrazine-induced aromatase expression is SF-1- dependent: Implications for endocrine disruption in wildlife and reproductive cancers in humans. Environ. Health Perspect doi:10.1289/ehp.9758 (available at

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