Arimidex most effective in cancer study 

After approximately 8 years, postmenopausal women with hormone-sensitive breast cancer who received Arimidex, generically known as anastrazole, had a lower risk of recurrence than women taking tamoxifen, investigators reported at the annual meeting of the San Antonio Breast Cancer Symposium.

The multinational study called the Arimidex, Tamoxifen, alone or in Combination (ATAC) trial involved 6,241 women with localized, invasive breast cancer.

Following treatment with surgery, radiotherapy, chemotherapy, or a combination of these primary treatments, the patients were randomly allocated to receive Arimidex, tamoxifen or both drugs for 5 years.

After an average of 68 months, women on Arimidex had a 15% greater disease-free survival and a 25% longer time to disease recurrence than women on tamoxifen. The time it took for the cancer to spread to distant regions of the body was approximately 16% longer and the development of new cancers was reduced by more than 50% with Arimidex.

More than 3 years after completion of treatment, the gap between tamoxifen and Arimidex widened for risk of recurrence and risk of distant spread, although there was no statistically significant difference between the two drugs on overall survival time.

Principal investigator in the United States, Dr. Aman U. Buzdar, of The University of Texas MD Anderson Cancer Center in Houston, told Reuters Health that "there is a persistently positive effect with Arimidex."

"Arimidex has a lot of the same adverse effects as tamoxifen, such as nausea and vomiting, hair loss, fever and risk of infection, but they are milder.

And once treatment has stopped, the risk of fractures with Arimidex drops back down to that of tamoxifen. There is no carry-over effect with fracture risk with Arimidex."

"Over time, the benefits (of Arimidex) become more striking, cutting the risk of recurrence in one out of four women. The risk of uterine cancer is also lower with Arimidex than tamoxifen," Buzdar added.

"The standard of care is changing for postmenopausal women" with breast cancer, Buzdar said.

Along with the meeting presentation, the ATAC results are being simultaneously published online December 14, 2007 by Lancet Oncology.

Investigator Dr. Anthony Howell of Christie Hospital NHS Trust in Manchester, UK, said in a Lancet statement that the new results from the ATAC study suggest that physicians should not wait to start their patients with early hormone receptor-positive breast cancer on anastrazole.

"The higher rates of recurrence (especially in years 1 through 3), and the increased numbers of adverse events and treatment withdrawals associated with tamoxifen, lend support to the approach of offering the most effective and well-tolerated therapy at the earliest opportunity."

"Five years of anastrozole should now be considered as the preferred initial adjuvant endocrine treatment for postmenopausal women with hormone-receptor-positive localized breast cancer," Howell concludes.