There isn’t good evidence for offering routine breast screening to all women under the age of 50 years. But, some younger women who have a strong family history of breast cancer can benefit from regular breast screening. At present, women with a strong family history of breast cancer are invited for screening with mammograms once they reach the age of 40 years.

Mammograms (breast x-rays) are used to screen women over 50 years of age for breast cancer. But, they are less reliable at screening breast tissue in younger women and may miss small cancers. This is because breast tissue is more dense in younger women.

MRI scans are an alternative to mammograms. These use magnetic rays to look at breast tissue. Four out of five studies that have compared MRI scans to mammograms have found that MRI scans are better at detecting early breast cancers in younger women.

The National Institute for Health and Clinical Excellence (NICE) advise the NHS in England and Wales on new developments in healthcare. NICE have recently issued guidance on breast screening for younger women with a strong family history of breast cancer. They say yearly screening with MRI scans should be offered to:

• women over 30 years of age who have inherited BRCA 1 or BRCA 2 gene mutations
• women over 20 years of age who carry the TP53 gene mutation.

Younger women at increased risk of breast cancer, but who haven’t been shown to have one of these gene mutations, should have their risk individually assessed by a specialist at a family cancer clinic. Depending on factors such as their:

• age
• assessed risk
• breast density.

They may be offered yearly MRI screening, yearly mammograms or no screening.

The guidance points out that MRI scans are more sensitive than mammograms. In other words they are better at picking up changes in the breasts of younger women. But they are less specific than mammograms. Which means they aren’t so good at telling whether changes are due to cancer or not. So, MRI scans can sometimes cause unnecessary worry because they find changes that turn out not to be cancer but involve women having to have tests such as breast tissue sampling (biopsy) to make sure of this.

The guidance also mentions that younger women at increased risk of breast cancer who are to be screened with mammography should be offered digital mammograms rather than standard (film) mammograms if they are available.

No decision has yet been taken on whether the guidelines will apply in Scotland.

Reference

• NICE CG41 Familial breast cancer. Updated July 2006.