“Anastrozole is the only aromatase inhibitor (AI) which has now been shown to prevent recurrences in women with hormone receptor positive early breast cancer both during the initial high-risk two years after surgery, and also well beyond the completion of treatment. In breast cancer there are no guarantees and we can’t predict which women will experience a recurrence or when, so it is essential we have a treatment that has sustained efficacy against all types of recurrence that persists even after treatment is completed. If we can stop breast cancer returning, we can stop women dying from it.” – Professor Tony Howell, Christie Hospital, UK
Macclesfield, UK, Friday 13 March 2009: A new analysis of the ATAC (ARIMIDEX, Tamoxifen, Alone or in Combination) trial, presented today at the 11th International St Gallen Oncology Conference, Switzerland, shows that during the first two years after surgery, anastrozole is superior to tamoxifen at reducing the risk of breast cancer returning in postmenopausal women with hormone receptor positive early breast cancer (n=5,216).1 Anastrozole has consistently demonstrated superiority over tamoxifen, both during the five-year treatment period and beyond treatment completion.2 This latest analysis provides further reassurance that prescribing anastrozole from the start protects women in the crucial first two years when the risk of recurrence is highest, meaning that fewer patients have to be told the devastating news that their breast cancer has returned.
When breast cancer returns, particularly outside the breast at distant sites such as bone, liver or lung, it is no longer curable. Therefore protecting women from recurrence is the number one priority for doctors and is imperative to saving lives. Although the risk of recurrence can persist for up to at least 15 years,3 the risk is at its greatest within the first two years following surgery, as seen in the ATAC study where over half of all excess recurrences and deaths among patients taking tamoxifen occurred in the first two and a half years.2
This latest analysis confirms that in women who benefit from treatment with AIs (84% of the total ATAC population) anastrozole is even more effective at preventing all types of early recurrence (32%; 2 years post surgery) than previously seen in the broader study population (17%; 2.5 years post surgery).1
Professor Howell continued, “It is now standard practice to assess the hormone receptor status of breast tumours to guide the best course of treatment. ATAC is a ground breaking study which has led to a significant change in treatment strategies in breast cancer with aromatase inhibitors, such as anastrozole, now replacing tamoxifen as the standard of care for postmenopausal women with hormone receptor positive disease in many countries. These new findings confirm that in the women who receive it in routine clinical practice, anastrozole offers reassuring protection against their cancer returning at the time of greatest risk, giving women the best chance of continuing their lives cancer-free.”
The ATAC trial is one of the world’s largest and longest-running clinical studies in postmenopausal women with early breast cancer. With a median follow-up of 100 months – significantly longer than any other adjuvant AI trial – ATAC provides further information on the safety profile of anastrozole which remains predictable, with no long-term safety concerns. As a result of the weight of efficacy and safety evidence for anastrozole, it is now the most widely prescribed AI worldwide, with over twice as many prescriptions as the next most widely prescribed AI and over 4 million patient years’ experience.4 These new data will offer doctors treating hormone receptor positive postmenopausal early breast cancer further confidence that initial treatment with anastrozole offers women the best chance of staying recurrence free.
Anastrozole offers sustained protection against recurrence, demonstrating significantly superior disease free survival, time to recurrence, time to distant metastases and reduced incidence of contralateral breast cancer compared with tamoxifen – a benefit which increases over time and persists even after treatment ends.2
In ATAC, there were fewer recurrences in women with hormone receptor positive breast cancer treated with anastrozole (n= 2,618) than tamoxifen (n=2,598) at 2, 5 and 9 years post-surgery (91 vs 133; 245 vs 312; 385 vs 488 respectively).1
At a median follow-up of 2 years, compared to tamoxifen, anastrozole:1
– reduces the risk of all recurrences by 32% (HR 0.68 [0.52-0.88])
– reduces the risk of distant metastases by 21% (HR 0.79 [0.58-1.07])
– reduces the incidence of contralateral breast cancer by 78%.
The ARIMIDEX, Tamoxifen, Alone or in Combination (ATAC) trial is one of the world’s largest and longest-running clinical studies in postmenopausal women with early breast cancer. ATAC is designed to investigate the comparative efficacy and tolerability of two adjuvant therapies: ARIMIDEX (anastrozole) and tamoxifen.
This analysis of ATAC reinforces the significant superiority of ARIMIDEX over tamoxifen at reducing the risk of breast cancer returning (also known as ‘recurrence’) in postmenopausal women with hormone receptor positive early disease.1 The ATAC data also show that, even approximately four years after treatment completion, the absolute reduction in the risk of disease recurrence continues to increase with ARIMIDEX compared with tamoxifen.2
AstraZeneca is a major international healthcare business engaged in the research, development, manufacture and marketing of prescription pharmaceuticals and the supply of healthcare services. It is one of the world’s leading pharmaceutical companies with healthcare sales of $26.47 billion and leading positions in sales of gastrointestinal, cardiovascular, neuroscience, respiratory, oncology and infection products. AstraZeneca is listed in the Dow Jones Sustainability Index (Global) as well as the FTSE4 Good Index. http://www.astrazeneca.com
ARIMIDEX (anastrozole) is a trademark, the property of the AstraZeneca group of companies.
1. Howell A, Forbes J, Cuzick J et al. Initial adjuvant therapy with anastrozole – early and late event data from the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial in the hormone-responsive population. St Gallen 2009 Poster
2. Saphner T, Tormey DC, Gray R. Annual hazard rates of recurrence for breast cancer after primary therapy. J Clin Oncol 1996; 14(10): 2738-46
3. ATAC Trialists’ Group. Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 100-month analysis of the ATAC trial. Lancet Oncol 2008; 9: 45-53
4. AstraZeneca IMS data on file
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