More Women Will Survive Breast Cancer With Arimidex (anastrozole) Than tamoxifen Data Shows

LONDON, December 9 /PRNewswire/ -- Breakthrough data show that Arimidex (anastrozole) is the first and only breast cancer drug in the 'aromatase inhibitor' (AI) class that provides postmenopausal women with early breast cancer, a significantly better chance of surviving their disease, compared with those women who remain on tamoxifen.[1] These new data were presented today for the first time at the international medical congress, the San Antonio Breast Cancer Symposium (SABCS).

The results of the latest study, carried out in postmenopausal women whose tumours grow with oestrogen[a], who had already taken tamoxifen for two years, show that replacing tamoxifen with anastrozole for the remainder of the five-year treatment period not only almost halves the likelihood of their breast cancer returning anywhere in the body, but more importantly, increases their chance of survival by nearly a third.[1]

"Survival is the ultimate goal in the treatment of early breast cancer and these results provide compelling evidence that anastrozole has the potential to save the lives of significantly more breast cancer patients who are postmenopausal and hormone-receptor positive. It is clear that at whatever point you use it, anastrozole is a more effective alternative to tamoxifen," said Dr Jeffrey Tobias, Professor of Cancer Medicine at University College Hospital, London.

Data from three similarly designed key international trials - ABCSG 8, ARNO 95 and ITA[b] - involving over 4,000 women who have undergone surgery and received tamoxifen for two years show that replacing tamoxifen with anastrozole after two years was more effective than remaining on tamoxifen for the full five-year treatment period. The women were monitored for an average of 2.5 years.[1]

The results confirm that replacing tamoxifen with anastrozole can significantly reduce the chances of the disease returning or spreading to other parts of the body and ultimately, save the lives of many women with early breast cancer. In the group of patients who started taking anastrozole, rather than remaining on tamoxifen:

- The risk of dying was reduced by 29% (HR 0.71; 95% CI 0.52 - 0.98; p=0.0377),

- The risk of the disease returning was reduced by 45% (HR 0.55; 95% CI 0.42 - 0.71; p<0.0001), and

- The risk of the disease spreading from the breast to other parts of the body was reduced by 39% (HR 0.61; 95% CI 0.45 - 0.83; p=0.0015).[1]

In addition, the meta-analysis showed that the safety profiles for anastrozole and tamoxifen were consistent with those previously observed.[1]

Every year 41,000 women in the UK are diagnosed with breast cancer, and approximately 32,800 of these are past the menopause (postmenopausal).[2] Seventy-five per cent of these postmenopausal women, representing approximately 60 per cent of the entire population affected by breast cancer, have tumours that grow with oestrogen[3], and are eligible for treatment with an AI.

"Importantly, we know that the risk of the cancer returning peaks in the first two years after surgery, and that women should be given an AI at the earliest opportunity to minimise the risk in this crucial period, and these significant new data highlight that for those women who are already taking tamoxifen, greater benefit may still be achieved by replacing tamoxifen with Arimidex," said Professor Mike Baum, Emeritus Professor of Surgery, University College London commented.

In the UK, Arimidex (anastrozole) is approved for use in the adjuvant (post-surgery) treatment of postmenopausal women with hormone receptor positive early invasive breast cancer.[4]

Previous data from the landmark ATAC (Arimidex, Tamoxifen Alone or in Combination) trial, reported at last year's San Antonio meeting, showed that women starting their treatment with anastrozole and continuing for the full five year period had a significantly reduced risk of disease recurrence (the disease returns anywhere in the body), including distant disease recurrence (when the disease returns somewhere else in the body, and cannot be cured) and contralateral breast cancer (the disease returns to the other breast), compared with tamoxifen for five years.[5] These data provided the basis for the licence extension issued by the Medicines and Healthcare products Regulatory Agency (MHRA) for the use of Arimidex in hormone-receptor positive postmenopausal women directly following surgery (June 2005), making it the first and only alternative to tamoxifen in this setting.

Dr Emma Pennery, Nurse Consultant for Breast Cancer Care said: "The goal of adjuvant therapy is to keep patients free from recurrence and the risk of serious side effects for as long as possible."

"The ATAC trial showed us that initiating treatment with Arimidex for a full five year treatment period gave greater efficacy, with fewer side effects than tamoxifen. These new data demonstrate that patients who have not been started on Arimidex initially may still gain significant benefit from it. This is very encouraging news for women with breast cancer," Dr Pennery continued.

"This is probably the best news a breast cancer patient can hear. I keep myself up-to-date on new developments in breast cancer, but hearing that the treatment you are taking has been proven to save lives is wonderful," said UK breast cancer patient, Diane Blackett from Mid Glamorgan. "I feel reassured taking Arimidex - knowing that I'm receiving the most appropriate treatment for me has given me peace of mind and confidence, but I know I was lucky to receive it when I did."

Notes to Editors

- The Hazard Ratio (HR) is a specific measurement used in clinical trials to compare two treatments. Comparing treatment A against treatment B, a HR of 1.00 indicates that there is an equal chance of experiencing a particular event or effect with both treatments. If the HR should fall below 1.00 there is a lower risk of experiencing an event or effect with treatment A and if the HR is greater than 1.00 it indicates an increased risk of an event or effect with treatment A.

- The overall risk of disease recurrence or death from any cause is also known as disease free survival (DFS).

- Breast Cancer Care is the UK's leading provider of information, practical assistance and emotional support for anyone affected by breast cancer. Every year we respond to over 2 million requests for support and information about breast cancer or breast health concerns. All our services are free. We are committed to campaigning for better treatment and support for people with breast cancer and their families. For more information call the Breast Cancer Care helpline free on 0808-800-6000 (textphone 0808-800- 6001) or visit www.breastcancercare.org.uk.

About the ATAC trial

- The Arimidex licence is based on the data from the five-year treatment completion analysis of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial, which compares five years of treatment with tamoxifen to five years of treatment with Arimidex, in women newly diagnosed with early breast cancer. 84% of patients in the trial had tumours which are known to respond to hormonal treatment [5]

- The recent definitive analysis shows that, in the population of women whose tumours are fuelled by oestrogen, completing five years' adjuvant treatment with Arimidex provides additional benefits, over and above those offered by the previous standard of care, tamoxifen, with a further:

- 26% reduction in the risk of recurrence (HR =0.74; p= <0.0002) over and above the 50% reduction seen with tamoxifen.[5]

- 53% reduction in the risk of contralateral breast cancer recurrence (i.e. in the opposite breast) (HR = 0.47; p = 0.001).[5] This finding led CRUK to conduct the IBIS II trial, which is looking at the effect of Anastrozole in the prevention of breast cancer.

- 16% reduction in the risk of distant recurrence (HR = 0.84; p= 0.056).[5]

- However, women experienced an increased risk of joint pain and fracture,[5] although fracture rates reported in the ATAC trial are similar to those seen in age-matched postmenopausal women. It is not known whether the fracture rates seen are due to a protective effect of tamoxifen, a specific effect of Arimidex or both.[5]

About Arimidex

- Arimidex - generic name 'anastrozole' - is a potent, highly selective, non-steroidal aromatase inhibitor (AI), prescribed for the treatment of hormone receptor positive early (localised) and advanced (metastatic) breast cancer in postmenopausal women.

- In the UK, Arimidex (anastrozole) is approved for use in the adjuvant (post-surgery) treatment of postmenopausal women with hormone receptor positive early invasive breast cancer.[4] It is the first aromatase inhibitor licensed for primary adjuvant treatment of breast cancer and is an alternative treatment choice to tamoxifen for postmenopausal women in this setting.

References:

[a] A breast cancer tumour that grows with a supply of oestrogen is known as hormone-receptor positive breast cancer. The majority of women with breast cancer are postmenopausal with hormone-receptor positive breast cancer.

[b] The Austrian Breast & Colorectal Cancer Study Group (ABCSG) 8, the Arimidex-Nolvadex (ARNO) 95 trial, and Italian Tamoxifen Arimidex (ITA) trial.

[1] Jonat W et al. Switching from adjuvant tamoxifen to anastrozole in postmenopausal women with hormone-responsive early breast cancer: a meta-analysis of the ARNO 95 trial, ABCSG Trial 8, and the ITA trial. Abstract No. 18. San Antonio Breast Cancer Symposium 2005.

[2] Cancer Research UK website. http://www.cancerresearchuk.org/aboutcancer/specificcancers/breastcancer?vers ion=2

[3] Cancer Research UK website: http://info.cancerresearchuk.org/cancerstats/geographic/cancerineu/commoncanc ers

[4] Arimidex SmPC, June 2005

[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; 365 (9453): 60-62.