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The Intergroup Exemestane Study (IES).

Disease site: Breast cancer

Treatment modality: Hormone therapy

Status: Closed

Trial details

The Intergroup Exemestane Study (IES) is a randomised double-blind trial in postmenopausal women with primary breast cancer who have received adjuvant tamoxifen for 2-3 years, comparing subsequent adjuvant exemestane treatment with further tamoxifen to complete a total of 5 years endocrine therapy.

The trial recruited 4,740 post-menopausal women from 37 countries between 1998 and 2003, who had undergone surgery for breast cancer and taken tamoxifen for two to three years. Half of the group continued taking tamoxifen while the other half switched to exemestane to complete a total of five years of hormone treatment. The trial has 3 associated sub-studies looking at bone metabolism, endometrial changes and quality of life.

The trial is run by the ICCG in collaboration with the ICR-CTSU and is run under the auspices of the Breast International Group. The ICCG overseas the activities of 20 cooperative trials groups located in 37 countries worldwide which have local responsibility for the trial.

In 2004 the trial released results early due to a significant reduction in the risk of recurrence or death in patients who switched to exemestane. In 2007 an updated analysis with over 2.5 years post treatment follow-up showed that the early disease related benefits appeared to be maintained and that exemestane reduces the risk of dying by approximately 17%. Exemestane also appeared to be safe and well tolerated with no significant differences seen in relation to cardiovascular events, small increases in musculoskeletal side effects, in particular fractures and fewer gynaecological symptoms.

Chief Investigator: Professor R. C. Coombes, Imperial College, London.

ICR-CTSU Scientific Lead: Professor Judith Bliss

ISRCTN: 11883920

Sponsor: Pfizer

Funding: Pfizer

Further information

More information on IES may be found on the ICCG homepage.

Publications and presentations

More than 20 publications and presentations have been made of IES data, including:

Bertelli G, Hall E, Ireland E, Snowdon CF, Jassem J, Drosik K, Karnicka-Mlodkowska H, Coombes RC, Bliss JM. Long-term endometrial effects in postmenopausal women with early breast cancer participating in the Intergroup Exemestane Study (IES)--a randomised controlled trial of exemestane versus continued tamoxifen after 2-3 years tamoxifen. Ann. Oncol. 2010;21(3):498-505

Coleman R, Banks L, Girgis S, Vrdoljak E, Fox J, Cawthorn S, Patel A, Bliss J, Coombes R, Kilburn L. Reversal of skeletal effects of endocrine treatments in the Intergroup Exemestane Study. Breast Cancer Res. Treat. 2010;124(1):153-61

Coleman RE, Banks LM, Girgis SI, Kilburn LS, Vrdoljak E, Fox J, Cawthorn SJ, Patel A, Snowdon CF, Hall E, Bliss JM, Coombes RC. Skeletal effects of exemestane on bone-mineral density, bone biomarkers, and fracture incidence in postmenopausal women with early breast cancer participating in the Intergroup Exemestane Study (IES): a randomised controlled study. Lanc. Oncol. 2007;8(2):119-27

Coombes R, Kilburn L, Snowdon C, Paridaens R, Coleman R, Jones S, Jassem J, Van de Velde CJH, Delozier T, Alvarez I, Del Mastro L, Ortmann O, Diedrich K, Coates A, Bajetta E, Holmberg S, Dodwell D, Mickiewicz E, Andersen J, Lonning P, Cocconi G, Forbes J, Castiglione M, Stuart N, Stewart A, Fallowfield L, Bertelli G, Hall E, Bogle R, Carpentieri M, Colajori E, Subar M, Ireland E, Bliss JM. Survival and safety of exemestane versus tamoxifen after 2-3 years' tamoxifen treatment (Intergroup Exemestane Study): a randomised controlled trial. Lancet 2007;369:559-70

Coombes RC, Paridaens R, Jassem J, Van de Velde CJH, Delozier T, Jones S, Hall E, Kilburn L, Snowdon CF, Bliss JM, for the Intergroup Exemestane Study. First mature analysis of the Intergroup Exemestane Study (IES). J. Clin. Oncol. 2006;24  (18S):LBA527

Fallowfield LJ, Bliss JM, Porter LS, Price MH, Snowdon CF, Jones SE, Coombes RC, Hall E. Quality of life in the Intergroup Exemestane Study: a randomized trial of exemestane versus continued tamoxifen after 2 to 3 years of tamoxifen in postmenopausal women with primary breast cancer. J. Clin. Oncol. 2006;24(6):910-17

Coombes RC, Hall E, Gibson LJ, Paridaens R, Jassem J, Delozier T, Jones SE, Alvarez I, Bertelli G, Ortmann O, Coates AS, Bajetta E, Dodwell D, Coleman RE, Fallowfield LJ, Mickiewicz E, Andersen J, Lonning PE, Cocconi G, Stewart A, Stuart N, Snowdon CF, Carpentieri M, Massimini G, Bliss JM. A randomized trial of exemestane after two to three years of tamoxifen therapy in postmenopausal women with primary breast cancer. N. Engl. J. Med. 2004;350(11):1081-92

Clinical trials

Division of Clinical Studies

The division carries out or coordinates high-quality trials and translational research at both an early phase – typically to test new targeted drugs – and a later stage.