Call for Anastrozole (Arimidex) to be the new preferred breast cancer treatment option

An international group of breast cancer experts called for the aromatase inhibitor (AI), anastrozole ('Arimidex'), to be considered as the new 'preferred treatment option' for postmenopausal women with early breast cancer.

This 'call to action' from the Steering Committee of the ATAC ('Arimidex', Tamoxifen, Alone or in Combination) trial, follows last week's publication of new breast cancer treatment guidelines from the American Society of Clinical Oncology (ASCO) in the Journal of Clinical Oncology.

For the first time, these guidelines recognise that 5 years' tamoxifen alone is no longer the optimal hormonal breast cancer treatment for these women, recommending that therapy, should now include the use of an aromatase inhibitor (AI), either initially or after treatment with tamoxifen, to 'lower the risk of tumour recurrence'. They go on to state that, as it is unknown if the three available drugs are interchangeable in clinical practice, the choice of AI should be based upon the agent that has been most studied in the relevant clinical setting.

These latest guidelines, however, were developed prior to the availability of pivotal data from the ATAC 5-year Completed Treatment Analysis, which were published in The Lancet in January 2005 (2). With these mature and conclusive data now demonstrating that 5 years' treatment with anastrozole can help more women live free of breast cancer with a lower risk of serious side effects than tamoxifen, there is an urgent need for the benefits of initial adjuvant therapy with anastrozole specifically to be reflected in future breast cancer treatment guidelines.

The conclusive ATAC data will be presented for the first time in Europe this week at the 'Primary Therapy of Early Breast Cancer' conference in St. Gallen, Switzerland. The meeting also hosts the 'International Consensus Conference on the Optimal Primary Therapy of Early Breast Cancer', which is aimed at reviewing and updating the international treatment guidelines that are published by this group. The ATAC steering committee's call for action is therefore directed towards this consensus panel who will be the first to be able to make specific recommendations for anastrozole taking into account the conclusive, mature data from the ATAC Completed Treatment analysis.

Commenting on the consensus panel's meeting this week, breast cancer expert and Chair of the ATAC steering committee, Professor Tony Howell said, "The ATAC Steering committee is calling for the St. Gallen Panel to be pivotal in creating greater access to anastrozole, the preferred treatment option for postmenopausal women with early breast cancer. We are all excited about the latest ATAC results and look forward to seeing them reflected in the discussions held at St Gallen. We hope the committee will acknowledge the importance of these data and become the first consensus group to reflect them in their guidelines, setting the expected level of treatment standard for women throughout the world."

Worldwide excitement and anticipation resulted from the first presentation of data from the ATAC Completed Treatment Analysis (3), at the San Antonio Breast Cancer Symposium, last December. The results showed that, for the first time in 30 years, there is a drug that has been proven to be more effective than tamoxifen in preventing all forms of breast cancer recurrence, including life-threatening distant recurrence. With the majority of women in the trial having now completed their 5-year course of treatment, the latest analysis on efficacy and safety represents the most mature data set available for any drug in its class.

As the median follow up in ATAC now extends beyond the recommended 5-year treatment period, it has become evident that the benefits of anastrozole over tamoxifen continue to increase over time and persist, even after a woman has finished her treatment. Anastrozole is the only AI to have delivered final tolerability and safety data relating to the full treatment period. This extensive and definitive data from the ATAC trial, proven clinical experience, and a licensed indication in early breast cancer mean that clinicians can be confident in recommending the use of anastrozole in postmenopausal women, newly diagnosed with early breast cancer.

Anastrozole's role in the prevention of breast cancer is also currently being researched.

For further information on the ongoing prevention trials, click on http://www.ibis-trials.org.

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