Study sheds new light on breast cancer hormone links

In collaboration with the Press Association

Some women who naturally produce higher levels of a protein called aromatase in their breasts may face an increased risk of developing breast cancer, US researchers have suggested.

This was among the tentative findings of a new study reported in the journal Cancer Research.

The research was conducted in mice by scientists at Georgetown Lombardi Comprehensive Cancer Centre, a part of Georgetown University Medical Centre.

It sheds new light on the role of aromatase, an enzyme that plays a key role in the production of oestrogen in the body.

The study suggests that overproduction of aromatase in breast tissue at least as important in accelerating breast cancer development than high levels of a second protein - the oestrogen receptor - used by the hormone to activate mammary cells.

Researchers also found that mice that produced more aromatase also had more oestrogen receptors on the breast cells.

Both proteins are already targeted by existing breast cancer therapies such as tamoxifen, which targets the oestrogen receptor, and anastrozole, which blocks aromatase.

But the Georgetown study suggests aromatase inhibitors may be a better choice for cancer prevention in postmenopausal women than tamoxifen and other drugs that block the oestrogen receptor.

Team leader Dr Priscilla Furth said: "We know that oestrogen is the fuel that most breast tumours use to grow and this study shows us that making more oestrogen in the breast, right next to cells that can use the hormone as fuel, appears to be a key trigger of early breast cancer."

Dr Julie Sharp, science information manager at Cancer Research UK, said: "It will be interesting to see if these results from mouse studies hold true in humans - if they do, it may be possible to measure women's aromatase levels and prevent cancer in those at greatest risk.

"Cancer Research UK scientists are investigating the aromatase-blocking drug anastrozole in postmenopausal women at risk of breast cancer in a clinical trial called IBIS-II - one of the largest cancer prevention studies in the world."

Copyright Press Association 2011


  • Diaz-Cruz, E., Sugimoto, Y., Gallicano, G., Brueggemeier, R., & Furth, P. (2011). Comparison of Increased Aromatase versus ER in the Generation of Mammary Hyperplasia and Cancer Cancer Research, 71 (16), 5477-5487 DOI: 10.1158/0008-5472.CAN-10-4652