NEW YORK (Reuters Health) - 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-percent greater
disease-free survival and a 25-percent 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-percent longer and the development of new
cancers was reduced by more than 50 percent 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.
