Preoperative treatment with Arimidex(TM) allows patients to undergo less extensive surgery


4th European Breast Cancer Conference - Hamburg, Germany. March 17 2004: New data presented today1,2, indicate that preoperative (neoadjuvant) treatment with ARIMIDEXTM (anastrozole) results in clinically beneficial reductions in tumour volume, extending the range of surgical options, which can allow patients to undergo less extensive surgery. This latest evidence adds to the already extensive clinical data set for anastrozole - the largest available for any aromatase inhibitor.

Anastrozole has already been shown, through the 9,366 patient ATAC ('Arimidex', Tamoxifen, Alone or in Combination) trial, to provide significant efficacy benefits compared with tamoxifen, in addition to a more favourable overall tolerability profile in the adjuvant treatment of postmenopausal women with early breast cancer3,4. Furthermore, the ITA (Italian Tamoxifen Anastrozole) trial was the first to show that changing adjuvant therapy from tamoxifen to the aromatase inhibitor, anastrozole after 2 3 years results in a lower risk of recurrence and fewer serious adverse events compared with continued tamoxifen treatment5. Anastrozole also has recognised benefits over tamoxifen in patients with advanced breast cancer where it is now an established first-choice treatment.6

The new data presented today highlighting the benefits of anastrozole in the preoperative setting come from the PROACT* trial and a prospective combined analysis of the results of the PROACT and IMPACT8, trials.

In the PROACT trial, 12 weeks' preoperative treatment with anastrozole was shown to have significant benefits compared with the established hormonal therapy, tamoxifen. For patients who were scheduled for a mastectomy or had tumours that were thought to be inoperable at the start of the trial, significantly more were able to undergo less extensive breast-conserving surgery (BCS) in place of mastectomy or to undergo surgery for a previously inoperable tumour, if treated with anastrozole compared with tamoxifen (43% vs. 31% respectively, odds ratio =1.69, p=0.04). These results were supported by a significant difference in the corresponding overall objective response (OR) rates** for these patients (OR for anastrozole = 37%, OR for Tamoxifen = 24%, odds ratio = 1.81, p=0.03).

The combined analysis of the IMPACT and PROACT trials included only the results available from the population common to both trials i.e. those patients who received either anastrozole or tamoxifen alone. Again, for the population with inoperable tumours or requiring mastectomy at study entry (n=344), less extensive surgery became feasible and was actually performed in significantly more patients treated with anastrozole compared with tamoxifen.

  • Feasible surgery: anastrozole 47% vs. tamoxifen 35% (odds ratio = 1.67, p=0.021)
  • Actual surgery: anastrozole 43% vs. tamoxifen 31% (odds ratio = 1.70, p=0.019)

These new data supporting the use of anastrozole in the preoperative setting are particularly significant when considering the results of an international survey, conducted by the NOP Research Group7, also released for the first time today. In this survey of over 1,700 women (aged 45 and over), 55% said initially that, if diagnosed with breast cancer, they would choose to undergo mastectomy. However, when presented with the option of receiving an effective treatment that could shrink their tumours and allow less extensive (breast-conserving) surgery, nearly half (47%) of women then opted for this alternative in preference to mastectomy. Furthermore, the survey highlighted the immense psychological impact of breast cancer - the fear of losing a breast was among the most common concerns voiced by these women.

Summarising the significance of these results, Professor L Cataliotti, one of the lead investigators for the PROACT trial, of the University degli Studi di Firenze, Italy, said: 'These exciting new data show us that anastrozole is significantly more effective than tamoxifen in downstaging tumours, allowing more patients to undergo breast conserving surgery rather than mastectomy. This is very promising news as the psychological impact of losing a breast should always be considered when reviewing treatment options available to our patients. Furthermore, if inoperable tumours can be made operable, this can have a hugely beneficial effect on a patient's quality of life'. ** assessed by ultrasound T Breast conserving surgery became feasible in those requiring mastectomy at entry or any type of surgery became feasible in those with tumours previously considered inoperable.

The new data from PROACT and the IMPACT / PROACT combined analysis suggest that more women may be able to avoid the devastating consequences of losing their breast if they are treated with anastrozole prior to surgery. Furthermore, if patients are given the choice to receive an effective preoperative treatment to avoid mastectomy, the results of the NOP survey suggest that many of them would prefer that option.

These results will also undoubtedly fuel the growing doubt among clinicians that tamoxifen still remains the most effective endocrine treatment for breast cancer. Anastrozole is the most extensively researched and used aromatase inhibitor, now with over one million patient years experience, and the continued and growing body of evidence suggests that anastrozole can be effective across the whole spectrum of breast cancer treatment.

With this new evidence to support its use in the preoperative setting, anastrozole is becoming recognised as a potential new first-choice treatment in endocrine breast cancer therapy for postmenopausal women.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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