A trial looking at anastrozole to prevent breast cancer in postmenopausal women (IBIS II Prevention)

You can enter this trial if you

• Are aged between 40 and 70
• Have been through your menopause
• Have not been diagnosed with breast cancer
• Have had DCIS treated by mastectomy within the last 6 months
• Have a high risk of developing breast cancer

You cannot enter this trial if you

• Are still having periods
• Have breast cancer, or have had breast cancer in the past (unless you have had DCIS - see criteria for specific age groups)
• Have had any other cancer in the last 5 years (except non melanoma skin cancer or carcinoma in situ of the cervix)
• Are currently having tamoxifen or raloxifene, or have had tamoxifen or raloxifene for more than 6 months in the last 5 years (women who took part in the IBIS I (IBIS 1) trial will be able to take part if they stopped treatment in this trial more than 5 years ago)
• Want to carry on taking HRT (hormone replacement therapy) that contains oestrogen
• Have had (or are planning to have) your breast(s) removed (a mastectomy) to try and prevent breast cancer
• Have any other serious medical conditions
• Have taken any other drug as part of a clinical trial within the last 3 months

If you have a strong family history of breast cancer, you may be able to join this trial. There is more information on the IBIS II trial website.

This is a randomised trial. It has 2 groups. The people taking part will be put into the groups by a computer. The trial will recruit 4,000 women.

The people in group 1 will take anastrozole once a day for 5 years. The people in group 2 will take a dummy tablet (placebo) once a day for 5 years. You will not know if you are taking the anastrozole or the placebo. Neither will the doctors and nurses at the hospital.

You will need to go to hospital for tests before you start taking part in the trial. This will include a mammogram (and maybe a biopsy to make sure you don’t have breast cancer). You will then have a mammogram at least once every 2 years (the frequency will vary slightly between hospitals).

You will have a blood test done before you start the trial, and again after 1 year and 5 years.

Before you start the trial, you will have a bone density scan (called a DXA or DEXA scan) and two spinal X-rays to check that your bones are not fragile. If these show that your bones are very fragile and so at high risk of breaking, you can still join the trial, but you will have to take a drug called a bisphosphonate.  Bisphosphonates help to protect your bones.  This is usually prescribed by your GP.

All women will be asked to go to the hospital to see a doctor after 6 months and 1 year of joining the trial. You will then see the doctor at least every year, but maybe more often (again, this will vary slighty between hospitals). A local trial coordinator will contact you every 6 months to check on you and to give you support and advice.

As with all treatments, anastrozole has some side effects. These include

• Hot flushes
• Vaginal dryness
• Hair thinning
• Carpal tunnel syndrome

More unusual side effects are

• Sickness
• Weight loss
• Diarrhoea
• Tiredness
• Headache
• Skin rash

If you do have problems with side effects, you may be able to take the tablet every other day rather than every day. It may also be possible to stop taking it for a while (maybe for 1 to 3 months), with the consent of the trial doctors.

There is more information about this trial on the IBIS II trial website.