Breast Cancer Treatment: Weighing the Hormonal Options
Tamoxifen has been the standard in hormonal breast cancer treatment for decades. But newer treatments are challenging tamoxifen's superiority.
To Kathryn Anderson, the hormonal treatment tamoxifen offered a
new lease on life. A survivor of breast cancer, she had been through two
surgeries, radiation therapy, and chemotherapy when her doctors put her on
Anderson is not alone. In the 25-plus years since tamoxifen
became a mainstay of breast cancer therapy, the pill has saved thousands of
lives. But now, newer hormonal agents known as aromatase inhibitors are
contesting the superiority of tamoxifen and competing for attention.
When Elizabeth Edwards announced in March that her breast cancer had
returned, her peers -- other breast cancer survivors -- expressed a range of
emotions. Topping the list was empathy for Edwards, whose cancer had spread to
her bones. There was also pride in her bravery: She chose to be open and honest
about an intensely personal health issue. Others found themselves reliving
their own diagnoses. And, of course, many could not help but give way to
gnawing worry about their own health. Edwards'...
One of the biggest concerns with tamoxifen is that it stops
working after five years, doctors say. Yet one-third of cancers that recur come
back between five and 10 years later.
Anderson says that after her five years of tamoxifen therapy
ended she always feared a recurrence, feeling that her safety net had gone
Until now. A study published in 2004 in The New England
Journal of Medicine showed that taking the aromatase inhibitor Aromasin
after two to three years of tamoxifen reduced breast cancer recurrence by
And in 2003, another study in the same journal showed that women could cut
their risk of recurrence by nearly half by taking the aromatase inhibitor
Femara after they completed about five years on tamoxifen.
And another recent study showed that postmenopausal women who
switch to another aromatase inhibitor, Arimidex, after two or three years of
tamoxifen therapy had fewer recurrences of cancer than those who continued to
take tamoxifen for the full recommended five years.
Aromasin Helps Prevent Cancer Recurrence
The Aromasin study, performed by R. Charles Coombes, MD, PhD, showed that
when postmenopausal women took Aromasin for two to three years following two to
three years of treatment with tamoxifen, the risk of breast cancer recurrence
dropped by 32% compared with women who continued to take tamoxifen.
It's a revolutionary finding, says Paul E. Goss, MD, PhD, director of breast
cancer prevention at Toronto's Princess Margaret Hospital and professor of
medicine at the University of Toronto. Goss was lead researcher on the Femara
study that showed it cut breast cancer recurrence nearly in half after five
years of tamoxifen.
"The extent of risk reduction surprised us," Coombes tells WebMD.
"It indicates a fair number of people become resistant to tamoxifen two to
three years after they start taking it."
Several smaller trials showed that Aromasin may also be effective for the
treatment of hormone-responsive metastatic breast cancer. In one study, 122
women who had received no prior hormone therapy were randomly assigned to get
tamoxifen or Aromasin. Disease stabilized for at least six months in 57% of
those on Aromasin vs. 42% on tamoxifen.
And in a study of 105 women who had previously been on
aromatase inhibitors, about one-fourth appeared to benefit from the newer
Aromasin appears to be useful for in women whose breast cancers
failed to respond to aromatase inhibitors like Arimidex or Femara, says
co-investigator David Cameron, MD, a medical oncologist at Western General
Hospital in Edinburgh, Scotland.