Arimidex most effective in breast cancer study
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.
Lancet Oncology 2007;7:633-643.
What breastcancer.org says about this article…
Arimidex most effective in breast cancer study
The study reviewed here provides another year of results for the ATAC (Arimidex and Tamoxifen Alone or in Combination) trial. The results continue to show that 5 years of Arimidex (chemical name: anastrozole) is better than 5 years of tamoxifen as the first hormonal therapy for post-menopausal women with early-stage hormone-receptor-positive breast cancer. Arimidex is better than tamoxifen for:
- increasing the time before the cancer comes back
- reducing the risk of the cancer spreading to other parts of the body
- reducing the risk of a new cancer developing in the other breast
It appears that even after 5 years of treatment is done, the benefits of Arimidex over tamoxifen continue and even increase.
Still, there is no real difference in overall survival time between the two medicines.
This latest study report also showed a result that hadn't been seen before. The higher risk of broken bones associated with Arimidex disappeared after the women stopped taking Arimidex.
Arimidex is an aromatase inhibitor, a medicine that lowers the amount of estrogen in the body. This means that less estrogen reaches bone cells, which can lead to bone thinning and weakening and an increased risk of broken bones. This side effect of Arimidex is the most troubling issue for some women. Doctors may recommend that women with osteoporosis take tamoxifen rather than Arimidex because of this possible side effect.
The women in the ATAC trial now have been followed for about 8 years -- 5 years while they took ether Arimidex or tamoxifen or both, and 3 years after they stopped taking the medicine. The ATAC trial began in 1999 and the researchers will continue to follow the women in the study until 2011.
While the evidence keeps building that aromatase inhibitors are the best hormonal therapy to start with after initial breast cancer treatment for post-menopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer, tamoxifen is still a good choice. For a number of reasons, including side effects and cost, tamoxifen may be a better choice for some women.
When you're deciding on a treatment plan, keep two things in mind:
- Every woman responds differently to treatment. What works for someone else may not work for you and what works for you may not work for someone else.
- Your treatment plan is not written in stone. You can always change treatments if another treatment has greater benefits and fewer side effects.
If you're a post-menopausal woman being treated for hormone-receptor-positive, early-stage breast cancer, talk to your doctor about the pros and cons of aromatase inhibitors compared to tamoxifen. If you're currently taking tamoxifen, discuss whether switching to an aromatase inhibitor makes sense for you. Together, you can decide on a treatment plan that is best for YOU.
