A trial comparing two hormone therapies for breast cancer (FALCON)

Cancer type:

Breast cancer

Status:

Results

Phase:

Phase 3

This trial compared fulvestrant and anastrozole for breast cancer in women who had been through the menopause. It was for women whose breast cancer could not be removed with surgery or had spread to another part of the body.

More about this trial

Most breast cancers in post menopausal Open a glossary item women need the hormone oestrogen to grow. Doctors often use drugs that either reduce the amount of oestrogen the body makes, or stop oestrogen getting to the cancer.

Anastrozole (Arimidex) works by reducing the amount of oestrogen the body makes. Fulvestrant (Faslodex) works by stopping oestrogen getting to the cancer cells.

When this trial was done, another small study had suggested that fulvestrant may be better at treating breast cancer than anastrozole. But researchers wanted to do a larger trial to find out more.

The aim of this trial was to compare fulvestrant with anastrozole to find out which is better for post menopausal women with breast cancer.

Summary of results

This trial showed that fulvestrant worked better than anastrozole for post menopausal women with breast cancer.

Results
This trial recruited 462 women with breast cancer that could not be removed with surgery, or had spread to another part of the body. They had all been through the menopause, and had not had hormone therapy before.

The women taking part were put into one of two treatment groups at random, and:

230 were in group 1 and had fulvestrant injections and dummy (placebo) anastrozole tablets
232 were in group 2 and had anastrozole tablets and dummy (placebo) fulvestrant injections

Neither the patients nor their doctors knew which group the women were in. This is called a double blind trial.

The research team looked at how long it was before there were signs that the cancer had started to grow. They found the most common length of time was:

16.6 months in the fulvestrant group
13.8 months in the anastrozole group

FALCON

They looked at the number of women who had some benefit from having treatment, and they found it was similar in the two groups:

180 out of 230 women (78%) in the fulvestrant group
172 out of 232 women (74%) in the anastrozole group

When the research team looked at the results in 2016, it was too early to say whether fulvestrant helped the women to live longer or not. At the time:

67 out of 230 women (29%) in the fulvestrant group had died
75 out of 232 women (32%) in the anastrozole group had died

They will look at this again in the future, to see if there is a difference between the two groups. We plan to update this page once these results are available.

Side effects
The number of women who had side effects during treatment was similar in the two groups. It was 73% of women in the fulvestrant group and 75% in the anastrozole group. Many were mild or didn’t last long. The most common side effects in both groups were joint pain and hot flushes.

Conclusion
The research team concluded that fulvestrant was better than anastrozole, for post menopausal women with breast cancer who have not had hormone therapy before. They suggest it should be used as a treatment for this group of women.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.