Tumors have usually been
classified by their morphologi
c appearan
ces. Unfortunately, these
current
classifi
cation s
chemes have serious drawba
cks. They are not able to stratify similar histopathologi
cal appearan
ces that will follow signifi
cantly different
clini
cal
courses or respond differently to
chemotherapy. The information that a spe
cifi
c mole
cular profile
correlates with important
clini
cal endpoints should permit physi
cians to take treatment de
cisions based on the mole
cular
chara
cteristi
cs of ea
ch tumor. Lessons from the metastati
c setting have been translated to the adjuvant setting, and several strategies have been evaluated in
clini
cal trials. The expression of estrogen re
ceptors (ER) in breast
can
cer enables physi
cians to make treatment de
cisions related to the use of hormonal manipulations. In this
context, the
challenge is to define a suitable subgroup of patients who will benefit from the addition of
chemotherapy. Otherwise, the la
ck of ER expression predi
cts no benefit from hormonotherapy. In this setting
chemotherapy plays a
central role. The sele
ction of the most appropriate regimen based on HER-2 status remains an un
certain strategy. However, the expression of the on
coprotein HER-2 has been linked to the probability of response to the target-designed mono
clonal antibody trastuzumab. The role of trastuzumab in the adjuvant setting is supported by the early results of three large
clini
cal trials presented at the Ameri
can So
ciety Clini
cal On
cology meeting in 2005. These trials have shown a striking impa
ct of trastuzumab on the main endpoints su
ch as disease-free survival and overall survival. In this
context, the integration of trastuzumab with taxane and anthra
cy
cline-based-
chemotherapy seems to be the appropriate
choi
ce.
This review will combine data from breast cancer biology with clinical evidence coming from large phase III trials in the attempt to propose a molecular targeted approach to the adjuvant treatment strategy of early breast cancer patients.