There is evidence that taking HRT reduces the ability of mammograms to detect early breast cancers in women between the ages of 50 to 70. HRT makes breast tissue denser and this makes it harder to see early cancers with mammograms. It is estimated that mammograms are about 25% less sensitive if HRT is taken. To put this in perspective:

• If 10,000 women who are not on HRT are screened about 60 cancers will be discovered,
• If 10,000 women taking HRT (between the ages of 50-70) are screened the number drops to about 45. So 15 cancers will have been missed that might otherwise have been found.

These figures, however, come mainly from screening programmes where just a single picture was taken of each breast (single view mammography). It is now known that taking pictures of the breast from two different positions (two view mammography) is more sensitive and likely to pick up early cancers in women on HRT. It was recommended that all screening in the UK should be using two view mammography by the end of 2003.

So if you are taking HRT, and are between the ages of 50 to 70, when you go for screening make sure you tell them you are taking HRT, and that you get a 'two view' mammogram taken.