New International Treatment Guidelines Verify Crucial Role of 'Arimidex'(TM) (Anastrozole) for Postmenopausal Women With Early Breast Cancer
Macclesfield, England (ots/PRNewswire)
Today, new guidelines from the prestigious St. Gallen 'International Consensus Conference on the Primary Therapy of Early Breast Cancer' were released ahead of publication on the Annals of Oncology website(1). For the first time, the St. Gallen consensus panel has confirmed that 5 years of treatment with an aromatase inhibitor (AI), such as anastrozole, is one of the best options for postmenopausal women with hormone-sensitive disease to protect against their cancer returning following surgery. A change in these treatment guidelines means more patients should now be offered the opportunity to benefit from the proven efficacy and tolerability advantages of anastrozole, allowing them to continue to live free of cancer for longer.
"The St. Gallen guidelines now recognise the crucial benefits that AIs, such as anastrozole, can offer to women in the primary adjuvant setting. They are the first international guidelines to be updated since the publication of the ATAC 5-year Completed Treatment Analysis - data that are already leading to the routine use of anastrozole, in place of tamoxifen, over a 5-year treatment period," said Professor Anthony Howell of Christie Hospital, Manchester, UK.
Anastrozole is the most studied of all the AIs and the only one
which has been confirmed superior to tamoxifen over the full 5-year
treatment period, as demonstrated by the results of the ATAC
('Arimidex', Tamoxifen, Alone, or in Combination) 5-year Completed
Treatment Analysis(2). Although other AIs have been studied in the
adjuvant setting, theydo not have such conclusive long-term efficacy and tolerability data to support their use as primary adjuvant therapy. In particular, there is already a difference in toxicity profiles emerging between aromatase inhibitors, with exemestane and letrozole showing early signs of cardiac side effects when compared with tamoxifen, which has not been seen with
anastrozole. The American Society of Clinical Oncology (ASCO) treatment guidelines, updated at the end of 2004, favour using the agent with the most data relevant to each
individual clinical setting and recognise that AIs should not be used interchangeably(3). Therefore, evidence-based medicine suggests that anastrozole should be the preferred AI to replace tamoxifen after breast cancer surgery.
Professor Howell continued: "Although all AIs have a similar mechanism of action, we have already seen that their toxicity profiles may be very different when used over long periods. We have extensive safety data for anastrozole and can be confident in its use."
By routinely offering anastrozole following surgery for breast cancer, doctors can provide women with the best chance of preventing their disease returning as well as reducing their risk of many of the serious adverse events associated with tamoxifen. Data recently presented at the ASCO Annual Meeting in May 2005, have confirmed the importance of starting adjuvant therapy with the most effective treatment available(4,5,6). The risk of recurrence and serious side effects that women experience, by taking tamoxifen in the first 2 - 3 years following surgery, cannot be offset by using an aromatase inhibitor later in the course of treatment.
However, if a woman is already part way through a 5-year course of tamoxifen it is not too late for her to benefit from anastrozole. The option to switch therapy from tamoxifen to anastrozole after 2 - 3 years of treatment is also supported in the St. Gallen guidelines.
Recent studies have confirmed that changing to anastrozole can still provide significant benefits in terms of reducing the risk of recurrence and serious side effects(7,8).
References
1) Goldhirsch A, Glick JH, Gelber RD et al. Meeting Highlights: International Expert Consensus on the Primary Therapy of Early Breast Cancer 2005. Ann Oncol. 2005; 0: 3261
2) 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: 60-62
3) Winer EP, Hudis C, Burstein HJ et al. American Society of Clinical Oncology Technology Assessment on the Use of Aromatase Inhibitors As Adjuvant Therapy for Postmenopausal Women With Hormone Receptor-Positive Breast Cancer: Status Report 2004. J Clin Oncol 2005; 23 93: 1-11
4) Houghton J on behalf of the ATAC Trialists' Group. Using
anastrozole as initial adjuvant treatment prevents early recurrences
and reduces adverse events: Updated data from the ATAC ('Arimidex',
Tamoxifen, Alone or in Combination) trial. Proc ASCO 2005; Poster
Number: A8 Abstract No: 5825) Duffy S on behalf of the ATAC Trialists' Group. Gynecological
adverse events including hysterectomy occur less frequently with
anastrozole than with tamoxifen: data from the ATAC ('Arimidex',
Tamoxifen, Alone or in Combination) trial. Proc ASCO 20056) Cuzick JM, Howell A. Optimal timing of the use of an aromatase inhibitor in the adjuvant treatment of postmenopausal hormone receptor-positive breast cancer. Proc ASCO 2005; Poster Number: J17 Abstract No: 658
7) 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: 455-62
8) Boccardo F. Switching to anastrozole (ANA) vs continued tamoxifen (TAM) treatment of early breast cancer (EBC). Updated results of the Italian tamoxifen anastrozole (ITA) trial. Proc ASCO 2005; Poster Number: 1 Abstract No: 526
Notes to Editors
AstraZeneca (LSE: AZN, NYSE: AZN) continues its tradition of research excellence and innovation in oncology that led to the development of its current anti-cancer therapies including 'ARIMIDEX' (anastrozole), 'CASODEX' (bicalutamide), 'FASLODEX' (fulvestrant), 'NOLVADEX' (tamoxifen), 'ZOLADEX' (goserelin), 'TOMUDEX' (raltitrexed) and 'IRESSA' (gefitinib) as well as a range of novel targeted products such as anti-proliferatives, anti-angiogenics, vascular targeting and anti-invasive agents. AstraZeneca is also harnessing rational drug design technologies to develop new compounds that offer advantages over current cytotoxic and hormonal treatment options. The company has over 20 different anti-cancer projects in research and development.
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