Switching to anastrozole has benefits for breast cancer patients
Switching to anastrozole (Arimidex) after two years’ treatment with tamoxifen results in a 40 per cent reduction in the risk of relapse for postmenopausal women with early breast cancer, compared with continuing tamoxifen for five years, a Lancet paper has shown (2005; 366:455).
A combined analysis of two separate trials, involving a total of 3,224
patients, found that there were 110 events, defined as local or distant
metastasis or contralateral breast cancer, in the tamoxifen groups at
median follow-up of 28 months compared with 67 events in the anastrozole
groups — a decrease of 40 per cent.
Three years after switching, event-free survival was 92.7 per cent for
patients who remained on tamoxifen and 95.8 per cent for patients switched
to anastrozole. The
patients who switched had fewer thromboses (P=0.034), but more fractures
(P=0.015) and reports of nausea (P=0.0162), than those who continued
to receive tamoxifen.
However, the authors warn that since the data only apply to women who
have already completed two to three years of adjuvant therapy, they cannot
be used to support a treatment strategy of starting with tamoxifen with
the intention of changing to an aromatase inhibitor after two or more
years. “It is still an open question whether or not one should
use tamoxifen first and then switch to anastrozole or start with an aromatase
inhibitor,” lead author Raimund Jakesz, of Vienna Medical School,
told The Journal.
“Although further investigation of the use of aromatose inhibitors
is necessary to ascertain the ideal sequence and duration of adjuvant
therapy,
this combined analysis confirms that postmenopausal women who receive
tamoxifen as adjuvant therapy should be switched to anastrozole after
two years of treatment,” the authors conclude. |
The
Pharmaceutical Journal
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