Treatment

Improved understanding of breast tumor cell biology
and molecular genetics is enabling researchers to design
cancer therapies that are tailored to the unique characteristics
of each patient and tumor. Such “rational
therapeutics” may have greater efficacy and fewer side
effects than conventional chemotherapy.150 Clinical
trials of targeted therapies such as tyrosine kinase
inhibitors have demonstrated benefits in patients with
advanced disease and may also delay or reverse
hormone resistance. The tyrosine kinase inhibitor
Lapatinib®, may be effective in delaying disease progression
in women with HER2-positive advanced breast
cancer who have become resistant to tratuzumab.151
Metronomic therapy, a relatively new concept in antiangiogenic
therapy (drugs that block blood supply to the
tumor), uses much lower and less toxic doses of chemo-therapy agents than currently used in combination with
an antiangiogenesis drug.152 A recent study in experimental
animals suggests that bisphosphonates, which
are currently used to treat bone metastases in advanced
breast cancer patients, may also be able to prevent bone
metastases in women with early breast cancer.153
A recent combined analysis of data from three clinical
trials found that advances in chemotherapy have
substantially improved survival for patients with lymph
node-positive, ER-negative tumors.154 Advances in
chemotherapy have had less of an impact for women
with ER-positive tumors, although those who receive
adjuvant hormonal therapy still have better disease-free
and overall survival than ER-negative patients. Research
is underway to identify which women with ER-positive
disease truly benefit from the addition of chemotherapy
to hormonal therapy.155 This research includes a new
clinical trial that will use information on the expression
of 21 genes in breast tumor tissue (using a tool called
Oncotype DX) to assign women to treatment groups
based on their predicted likelihood of recurrence.