Breast cancer is the most common cancer in women worldwide. Although breast
cancers are generally oestrogen receptor positive initially, a substantial proportion
become oestrogen receptor negative. Oestrogen receptor positive breast cancers are
associated with a better prognosis than oestrogen receptor negative breast cancers as
they are more responsive to hormonal therapy.
Breast cyst fluid (BCF) is known to be a rich source of steroid hormones and
growth factors. These substances may have significant effects on mammary epithelial
cell growth and oestrogen metabolism in the breast and may, thus, play important roles
in the pathophysiology and development of breast cancer. Oestrone sulphate acts as a
large reservoir of active oestrogens in the breast and is converted to oestrone by the
enzyme oestrone sulphatase. The aims of the present study were to assess the effects of
BCF on cell growth of, and oestrone sulphatase activity in the MCF-7 oestroge
