Ruth M. O'Regan, MD

The use of aromatase inhibitors
has increased dramatically in
the past few years as a result
of the emergence of new, more specific
agents, such as anastrozole
(Arimidex), exemestane (Aromasin),
and letrozole (Femara). This class of
agents effectively blocks the peripheral
formation of estradiol, decreasing
its concentration to less than 10%,
while maintaining selectivity.[1]
Evaluation of these selective aromatase
inhibitors as adjuvant therapy
for early-stage breast cancer was
based on the findings of trials in
metastatic breast cancer, summarized
by Visvanathan and Davidson, that
demonstrated the equivalence and,
in some cases, superiority of the
aromatase inhibitors compared
with megestrol and tamoxifen,
including their superior side-effect
profile.[2-4]