Aromasin Beats Tamoxifen ... Again
Aromatase Inhibitor May Be More Effective for Metastatic Breast Cancer
March 19, 2004 (Hamburg, Germany) -- A new study shows that women with metastatic breast cancer lived longer if they took Aromasin rather than tamoxifen. The news comes just a week after a study showed that women with breast cancer lived longer when they took tamoxifen and later switched to the hormone therapy drug Aromasin.
Most breast cancers are estrogen-sensitive, meaning they grow in response to estrogen. Both tamoxifen and Aromasin -- one of a newer class of drugs called aromatase inhibitors -- decrease this estrogen effect. Tamoxifen, used following chemotherapy and surgery, was the only estrogen-blocking drug available for many years. But recently, studies have shown that aromatase inhibitors may be even more effective than tamoxifen. Other aromatase inhibitors are Arimidex and Femara.
"Although [Aromasin] may have advantages over tamoxifen, we don't know whether all patients with estrogen-sensitive breast cancer should receive this drug," researcher Robert Paridaens, MD, tells WebMD. "The treatment of advanced breast cancer still needs to be developed for each individual patient." Paridaens is a medical oncologist at the University Hospital Gasthuisberg in Leuven, Belgium.
The new study involved 382 postmenopausal women with metastatic breast cancer that took either tamoxifen or Aromasin.
With metastatic breast cancer, the goal of treatment is to be survival-free of breast cancer and to have the fewest possible side effects from treatment, says Paridaens.
On average, breast cancer recurred after approximately 10 months in women who took Aromasin, compared with six months for the women who took tamoxifen.
Aromasin and other aromatase inhibitors should only be used in women who have already passed menopause, says Clifford Hudis, MD, who was not involved in the study.
"In the various studies involving aromatase inhibitors, we have seen the same effect: if you substitute a drug in this class with tamoxifen or add it on, patients have fewer recurrences, and longer time to progression." Hudis is chief of breast cancer medicine service, Memorial Sloan Kettering Cancer Center, New York City.
Aromatase inhibitors often cause hot flashes, and women taking these drugs frequently complain of muscle and joint aches. However, aromastase inhibitors are less likely than tamoxifen to cause blood clots and, unlike tamoxifen long-term use does not increase the risk of uterine cancer.
Because these drugs block estrogen, they also increase the risk of bone thinning that may cause osteporosis, Hudis says.
"There is still some tradeoff of side effects between aromatase inhibitors and tamoxifen. Patients on tamoxifen should not panic, because therapy should still be individualized. They should discuss whether an aromatase inhibitor would have any benefits, and whether they should switch from tamoxifen to one of these drugs or add it on to their treatment regimen."