“…Previous studies have evaluated either urinary oestrogen excretion (Persson & Risholm, 1964;Marmorston et al, 1965;Gronroos & Aho, 1968;Argeulles et al, 1973;Grattarola et , 1974;Thijssen et al, 1975;Morreal et al, 1979) or oestrogen concentrations in the blood (England et al, 1974;McFadyen et al, 1976;Malarkey et al, 1977;Adami et al, 1979;Drafta et al, 1980;Moore et al, 1982;Reed et al, 1983Reed et al, , 1985Secreto et al, 1983;Bruning et al, 1985;Siiteri et al, 1986;Wysowski et al, 1987) of breast cancer cases and controls. These studies have suggested that post-menopausal breast cancer cases have higher endogenous oestrogen levels than controls: five of the seven studies of urinary oestrogen levels found evidence of greater oestrogen excretion in cases (Persson & Risholm, 1964;Marmorston et al, 1965;Arguelles et al, 1973;Grattarola et al, 1974;Morreal et al,1979); of the studies comparing blood levels of E, and E2 in cases and controls, three of five found higher E, (Adami et al, 1979;Drafta et al, 1980;Reed et al, 1983) and eight of 11 found higher E2 levels in cases (England et al, 1974;McFadyen et al, 1976;Malarkey et al, 1977;Drafta et al, 1980;Moore et al, 1982;Reed et al, 1985;Bruning et al, 1985;Siiteri et al, 1986).…”