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Women With Early Breast Cancer are More Likely to Remain Cancer Free by Changing Treatment From Tamoxifen to Anastrozole

Data Published in the Lancet Oncology Report That Patients are More Likely to Live Cancer Free for Longer if Tamoxifen is Replaced With Arimidex(TM)

WASHINGTON, DC -- November 17, 2006 -- According to data published today in the Lancet Oncology, women with early breast cancer, who have their treatment swapped from tamoxifen to Arimidex(TM) (anastrozole) at 2-3 years, have a better chance of living cancer free for longer than if they continue taking tamoxifen[1].

The data are from a meta-analysis of three key international trials[2,3,4] and confirm that, in postmenopausal women with hormone-sensitive disease, replacing tamoxifen with anastrozole can almost halve the likelihood of disease recurrence. Furthermore, with survival being the ultimate goal, changing treatments can reduce the risk of death by nearly a third.

Commenting on these data, lead author of the meta-analysis, Professor Walter Jonat of the University of Kiel, Germany said, "These data will be welcome news to the many thousands of women around the world who are currently taking tamoxifen to help prevent the recurrence of early breast cancer. By changing treatment, their chances of beating the disease and living longer cancer free can be greatly improved, giving them more confidence for the future."

The three trials in the meta-analysis were similarly designed to assess, in women already being treated with tamoxifen, whether or not replacing tamoxifen with anastrozole after 2-3 years was more effective than continuing to take tamoxifen for the full 5-year treatment period. The combined data show, at a median follow-up of 30 months, that replacing tamoxifen with anastrozole can significantly reduce recurrence, prevent metastatic spread and ultimately save the lives of many women with early breast cancer.

Women who changed to anastrozole, rather than remaining on tamoxifen, experienced a;

- 29% improvement in overall survival (HR 0.71; 95% CI 0.52 - 0.98; p=0.0377), i.e. the risk of dying was reduced by almost a third

- 45% improvement in event-free survival (HR 0.55; 95% CI 0.42 - 0.71; p<0.0001), i.e. the risk of the disease returning was reduced by almost half and

- 39% improvement in distant recurrence-free survival (HR 0.61; 95% CI 0.45 - 0.83; p=0.0015)[1].

Getting it right from the start
Although these data are a valuable finding for women already taking tamoxifen for the treatment of hormone-sensitive, early breast cancer, it is important to remember that the findings do not apply to women newly diagnosed with the disease. For these patients, recent evidence and opinion show the importance of using anastrozole rather than tamoxifen right from the start[5-7]. There are currently no data demonstrating any benefit of a planned sequencing strategy of two therapies over 5 years of tamoxifen alone in patients with early breast cancer.

"The landmark ATAC trial established that starting treatment with anastrozole at the earliest opportunity after surgery, and giving it for the full 5 years of treatment, is not only more effective than tamoxifen for the prevention of disease recurrence but better tolerated as well. This would suggest that the best place to use anastrozole is right from the start. The important data published in the Lancet Oncology today demonstrate that patients who have not had the benefit of starting treatment on anastrozole, can still gain from the significant benefits of anastrozole, by switching at 2 years," stated Prof. Jeffrey Tobias of University College Hospital, London, United Kingdom.

Anastrozole was granted a new licence indication in Europe in July 2006, confirming its approval for use following 2-3 years of tamoxifen therapy. This approval was granted on the basis of the disease-free survival benefit for anastrozole demonstrated in the three individual trials included in the meta-analysis. Anastrozole is now the first and only aromatase inhibitor to be approved both for primary adjuvant use and following 2-3 years' treatment with tamoxifen.

REFERENCES:
1. Jonat W, Gnant M, Boccardo F et al. Effectiveness of switching from adjuvant tamoxifen to anastrozole in postmenopausal women with hormone-sensitive early-stage breast cancer: a meta-analysis. Lancet Oncology. Published online November 17, 2006 DOI:10.1016/S1470-2045(06 )70948-2
2. Jakesz, R. et al. The benefits of sequencing adjuvant tamoxifen and anastrozole in postmenopausal women with hormone-responsive early breast cancer: 5 year-analysis of ABCSG Trial 8. Abstract No. 13. San Antonio Breast Cancer Symposium 2005
3. Jakesz R, Jonat W, Gnant M et al. Switching of postmenopausal women with endocrine-responsive early breast cancer to anastrozole after 2 years' adjuvant tamoxifen: combined results of ABCSG trial 8 and ARNO 95 trial. Lancet 2005; 366 (9484):455-462
4. Boccardo F, Rubagotti A, Puntoni Met al. Switching to anastrozole versus continued tamoxifen treatment of early breast cancer: Preliminary results of the Italian Tamoxifen Anastrozole trial. Journal of Clinical Oncology 2005; 23 (22):5138-5147
5. ATAC Trialists' Group. Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial after completion of 5 years' adjuvant treatment for breast cancer. Lancet. 2005 Jan 1-7;365(9453):60-62
6. Buzdar A, Chlebowski R, Cuzick J et al. Defining the role of aromatase inhibitors in the adjuvant endocrine treatment of early breast cancer. Curr Med Res Opin 2006;22(8):1575-85
7. ATAC Trialists' Group. Comprehensive side-effect profile of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: long-term safety analysis of the ATAC trial. Lancet Oncology. 2006 Aug;7(8):633-43

Meta-analysis includes:

ABCSG - Austrian Breast & Colorectal Cancer Study Group,
ARNO - 'Arimidex' - 'Nolvadex',
ITA - Italian Tamoxifen Anastrozole
ATAC - 'Arimidex', Tamoxifen, Alone or in Combination

'Arimidex', is a trademark, the property of the AstraZeneca group of companies.


SOURCE: AstraZeneca

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