Reduced risk of oestrogen receptor positive breast cancer among peri- and post-menopausal women in Scotland following a striking decrease in use of hormone replacement therapy

For ER positive tumours in the 50-64 age group, age-standardised rates increased 31.5% from 1997 to 2000, followed by a statistically significant decrease of 11.2% by 2005 (change in slope = −0.0943, P < 0.0001). We conclude that an overall incidence in the 50-64 age group declined since 2000 reflecting the sudden fall in HRT dispensed items and is largely accounted for by the decrease in ER positive tumour incidence. A longer term decline in ER negative tumours for this age group was pre-existing and is unaffected by the collapse in HRT prescribing.