New Breast Cancer Survival Data From The Intergroup Exemestane Study (IES) Published In The Lancet Today

Main Category: Breast Cancer
Also Included In: Cancer / Oncology
Article Date: 13 Feb 2007 - 12:00 PDT

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New data from the Intergroup Exemestane Study (IES), published in the Lancet today show that, 2 to 3 years after the end of their treatment, postmenopausal women with oestrogen sensitive early breast cancer who switched to exemestane (AROMASIN™) after 2 to 3 years of tamoxifen are 15% - 17% more likely to be alive, compared to patients who remained on tamoxifen for the full five years of therapy. These data also demonstrated that patients who switched to exemestane are 25% less likely to have their cancer return than patients who continued on tamoxifen.1

Lead Investigator Professor Charles Coombes, Director of Cancer Medicine, Imperial College, London explained: "Exemestane, when given after 2-3 years tamoxifen, reduces the risk of dying by an additional 15-17% in women with endocrine (hormone) responsive breast cancer, which accounts for 80-85% of all cases in postmenopausal patients. Since tamoxifen reduces the risk of dying by 31%, by sequencing, we have shown that the benefit is to nearly half the risk of dying when compared with no endocrine treatment."

The Lancet publication reinforces the strength of the exemestane data and follows NICE's Final Appraisal Determination (FAD) on hormonal therapies for the adjuvant treatment of early oestrogen-receptor-positive breast cancer. Exemestane is the only treatment option recommended by NICE as an alternative to continued tamoxifen for women who have already received 2-3 years of initial adjuvant tamoxifen therapy.2

It is estimated that 31,000 postmenopausal women are diagnosed with breast cancer every year in the UK.2 Exemestane works in postmenopausal women where the hormone oestrogen promotes tumour growth, which occurs in over two thirds of cases.3 Tamoxifen blocks the effects of oestrogen on cancer cells, whereas exemestane inhibits the body's production of oestrogen, stopping the supply of oestrogen to the cancer cells.

"Exemestane is now available in the UK to the thousands of postmenopausal women who have been and will be diagnosed with oestrogen sensitive breast cancer," said Dr Mary McCormack, Consultant Clinical Oncologist, University College London Hospital. "It is important that women with the disease who have received tamoxifen for two to three years, are fully informed of the potential benefits of switching therapy," she continued.

AROMASIN (exemestane) indication

AROMASIN (exemestane) is indicated for the adjuvant treatment of postmenopausal women with oestrogen receptor positive invasive early breast cancer, following 2 -3 years of initial adjuvant tamoxifen therapy. It has been licensed for the treatment of advanced breast cancer in patients that have progressed on anti-oestrogen therapy since 1999.

About the Intergroup Exemestane Study (IES)1

• The IES is a randomised phase III double-blind study in postmenopausal women with oestrogen sensitive early breast cancer. The study was designed to test whether, switching to exemestane after 2-3 years of tamoxifen was more effective than continuing tamoxifen therapy for the remainder of the five years of treatment

• The study enrolled 4,742 patients from 37 countries and 20 co-operative groups
-- Exemestane group = 2,362 patients
-- Tamoxifen group = 2,380 patients

• Average time on tamoxifen prior to switching to exemestane: 28 months
-- Median follow-up of updated efficacy analysis: 55.7 months

• Compared to continuing tamoxifen therapy, switching to exemestane after 2-3 years of tamoxifen in postmenopausal women with early breast cancer fuelled by oestrogen has been shown to:
-- improve disease free survival by 24 percent
-- reduce the risk of the breast cancer coming back by 24 percent
-- reduce the risk of cancer occurring in the other breast by 43 percent

• Aromasin® was generally well tolerated across all studies and in the clinical studies, conducted with Aromasin®, undesirable effects were usually mild to moderate. The withdrawal rate due to adverse events in studies was 6.3% in patients with early breast cancer receiving adjuvant treatment with Aromasin® following initial adjuvant tamoxifen therapy.
- The most commonly reported adverse reactions were hot flushes (22%), arthralgia (17%) and fatigue (17%).
- Fractures occurred in 277 patients; 162 (7%) exemestane-treated patients and 115 (4.9%) tamoxifen-treated patients (p=0.003). Hip, spine and wrist fracture rates were low. During adjuvant treatment with Aromasin®, women with osteoporosis or at risk of osteoporosis should have their bone mineral density formally assessed by bone densitometry at the commencement of treatment.
- Most adverse reactions can be attributed to the normal pharmacological consequences of oestrogen deprivation (e.g. hot flushes).

• Lead investigator:
Professor Charles Coombes
Head of Department, Cancer Medicine - Imperial College School of Medicine

Breast cancer facts4

• Breast cancer is the most common cancer in women, around 42,000 women are diagnosed each year in the UK

• The strongest risk factor for breast cancer is age: the older the woman the higher the risk

• Most cases (around 80%) of breast cancer occur in postmenopausal women - approximately 8,000 women were diagnosed before their menopause in the UK in 2000

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References

1 Coombes RC, Kilburn LS, Snowdon CF, on behalf of the Intergroup Exemestane Study. Survival and safety of exemestane versus tamoxifen after 2-3 years' tamoxifen treatment (Intergroup Exemestane Study): a randomised controlled trial. Lancet 2007; published online Feb 13.DOI:10.1016/S0140-6736(07)60200-1.

2 National Institute of Clinical Excellence, Final Appraisal Determination. Hormonal therapies for the adjuvant treatment of early oestrogen-receptor-positive breast cancer: www.nice.org.uk Accessed August 2006

3 Health-cares.net. Hormone therapy for breast cancer, Available here. Accessed August 2006

4 Breast Cancer Care. Statistics and facts about breast cancer, Available here. Accessed August 2006