Arimidex most effective in breast cancer study

NEW YORK (Reuters Health) - After approximately 8 years,postmenopausal women with hormone-sensitive breast cancer whoreceived (Arimidex), generically known as anastrazole, had alower risk of recurrence than women taking tamoxifen,investigators reported at the annual meeting of the San AntonioBreast Cancer Symposium.
The multinational study called the Arimidex, Tamoxifen,Alone or in Combination (ATAC) trial involved 6,241 women withlocalized, invasive breast cancer. Following treatment withsurgery, radiotherapy, chemotherapy, or a combination of theseprimary treatments, the patients were randomly allocated toreceive Arimidex, tamoxifen or both drugs for 5 years.
After an average of 68 months, women on Arimidex had a15-percent greater disease-free survival and a 25-percentlonger time to disease recurrence than women on tamoxifen. Thetime it took for the cancer to spread to distant regions of thebody was approximately 16-percent longer and the development ofnew cancers was reduced by more than 50 percent with Arimidex.
More than 3 years after completion of treatment, the gapbetween tamoxifen and Arimidex widened for risk of recurrenceand risk of distant spread, although there was no statisticallysignificant difference between the two drugs on overallsurvival time
Principal investigator in the United States, Dr. Aman U.Buzdar, of The University of Texas MD Anderson Cancer Center inHouston, told Reuters Health that "there is a persistentlypositive effect with Arimidex."
"(Arimidex) has a lot of the same adverse effects astamoxifen, such as nausea and vomiting, hair loss, fever andrisk of infection, but they are milder. And once treatment hasstopped, the risk of fractures with Arimidex drops back down tothat of tamoxifen. There is no carry-over effect with fracturerisk with Arimidex."
"Over time, the benefits (of Arimidex) become morestriking, cutting the risk of recurrence in one out of fourwomen. The risk of uterine cancer is also lower with Arimidexthan 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 arebeing simultaneously published online December 14, 2007 byLancet Oncology.
Investigator Dr. Anthony Howell of Christie Hospital NHSTrust in Manchester, UK, said in a Lancet statement that thenew results from the ATAC study suggest that physicians shouldnot wait to start their patients with early hormonereceptor-positive breast cancer on anastrazole.
"The higher rates of recurrence (especially in years 1through 3), and the increased numbers of adverse events andtreatment withdrawals associated with tamoxifen, lend supportto the approach of offering the most effective andwell-tolerated therapy at the earliest opportunity."
"Five years of anastrozole should now be considered as thepreferred initial adjuvant endocrine treatment forpostmenopausal women with hormone-receptor-positive localizedbreast cancer," Howell concludes.
Lancet Oncology 2007;7:633-643.