A new study claims a
class of hormonal drugs called aromatase inhibitors may significantly reduce
the risk of death among postmenopausal women with estrogen receptor-positive
breast cancer - the most common form of the disease.
Lead study author
Prof. Mitch Dowsett, of The Institute for Cancer Research (ICR) in the UK, and
colleagues publish their findings in The Lancet.
It is estimated
that around 231,840 women will be diagnosed with invasive breast cancer this
year, and more than 40,000 will die from the condition.
receptor-positive (ER-positive) breast cancer accounts for around 70% of all
cases, in which breast cancer cells contain receptors that attach to the
hormone estrogen. When the hormone binds to these receptors, this can encourage
the growth of breast cancer tumors.
At present, women
with ER-positive breast cancer may be treated with tamoxifen - a drug that
prevents estrogen from binding to receptors in breast cancer cells. The drug is
primarily prescribed for women with early-stage breast cancer who have
undergone surgery, radiation and/or chemotherapy in order to prevent
According to Prof.
Dowsett and colleagues, taking tamoxifen for 5 years is associated with a 30%
reduction in breast cancer death. But their study suggests another class of
hormonal drugs - called aromatase inhibitors - may be more effective.
inhibitors lower estrogen levels by preventing the enzyme aromatase - found in fat tissue - from changing other hormones
into estrogen. As such, there is less estrogen to bind to receptors in breast
In the US, aromatase inhibitors are
currently used to treat early-stage breast cancer in postmenopausal women who
have been treated with tamoxifen for around 2-3 years.
Previous research suggests aromatase
inhibitors are more effective for reducing breast cancer recurrence than
tamoxifen, though how they impact survival has been unclear.
Aromatase inhibitors reduced breast cancer mortality by 40%
For their study,
the team analyzed the data of nine clinical trials involving 31,920
postmenopausal women with early-stage ER-positive breast cancer. The women in
the trials had either received no hormonal therapy or had used aromatase
inhibitors or tamoxifen for at least 5 years.
Compared with women who had not
received hormone therapy, those who received aromatase inhibitors were 40% less
likely to die from breast cancer in the 10 years after treatment initiation.
Women who took tamoxifen were at around 30% lower risk of breast cancer death.
"Our global collaboration has revealed that
the risk of postmenopausal women with the most common form of breast cancer
dying of their disease is reduced by 40% by taking 5 years of an aromatase
inhibitor - a significantly greater protection than that offered by tamoxifen.
Aromatase inhibitors remove only the
tiny amount of estrogen that remains in the circulation of women after the
menopause - but that's enough to have a substantial impact on a wide range of
ER-positive tumors, despite their extraordinary differences at the molecular
researchers note that treatment with aromatase inhibitors may present a number
of side effects. These can include shortness of breath, chest pain, hot
flashes, muscle or joint pain and depression.
important to ensure that women with significant side effects are supported to
try to continue to take treatment and fully benefit from it," notes Prof.
Earlier this month, Medical News
Today reported on a study published in Nature suggesting half of
breast cancers could be slowed if the hormone progesterone was added to
Source: Medical News Today