Science Interviews

Clinical Trials For a Breast Cancer Drug

Professor Jack Cuzick, Cancer Research UK

Kat - We've been talking about drugs and how you discover new drugs, but you're running clinical trials to test whether a drug can prevent cancer. Can you tell us a bit more about that?

Jack - This was an idea of a new use for a relatively old drug. The aromatase inhibitors are becoming established as the treatment of choice for breast cancer now, particularly in post-menapausal women. We noticed from looking at those trials that not only did they stop the old tumours from coming back but they were also blocking up to 75% of new tumours.

Kat - What are aromatase inhibitors?

Jack - Basically they're drugs that prevent the creation of oestrogen in post-menopausal women. Once the ovaries stop making oestrogen, oestrogen is made in the peripheral tissues by converting androgens with an enzyme called aromatase. Aromatase inhibitors block that pathway.

Kat - And is oestrogen bad for breast cancer?

Jack - Oestrogen stimulates the breast and they certainly stimulate breast cancers, so by getting rid of oestrogen, we really stop most of the stimulus to the breast. It has a very big effect on reducing recurrence and we think also on preventing new cancers.

Kat - So this new trial you're running is called IBIS2. How many people are you hoping to recruit for the trial? What sort of women are you looking for?

Jack - IBIS2 has two components to it. The most relevant is the component for women with high risk of breast cancer. We're looking for 6000 women who are at post-menopausal and at increased risk of breast cancer. The increased risk is mostly related to having a family history, such as if your mother and a sister has had breast cancer.

Kat - So will these women be given aromatase inhibitors?

Jack - The women all get very careful follow up and it's a randomised trial. The only way we can make progress and see if this works is if all women who get a tablet in which half is aromatase inhibitor and half is a dummy compound.

Kat - And you follow the women for how long?

Jack - Treatment is for five years, and then we follow them up for at least another five years. So it'll be at least a ten year trial before we get a complete answer.

Kat - If there are women listening to the show now who are post-menopausal, have a family history of breast cancer or have had a benign tumour removed, what can they do to get involved with the trials?

Jack - The easiest way to contact us to go to our website, which is www.ibis-trials.org. All the information to join the trials is there. You can also call on 020 7 014 0251.

February 2006