chapter  6
Gene Expression Profiling as an Emerging Diagnostic Tool to Personalize Chemotherapy Selection for Early Stage Breast Cancer
ByCornelia Liedtke, Lajos Pusztai
Pages 20

The selection of adjuvant chemotherapy for breast cancer is currently more of an

art than a science. Several combination chemotherapy regimens can improve

disease-free and overall survival of stage I to stage III breast cancer when used as

adjuvant (postoperative) or neoadjuvant (preoperative) therapy (1,2). However,

no chemotherapy regimen is universally effective for all patients, and it is cur-

rently impossible to predict which of these regimens will actually work for a

particular individual. Choosing the best possible adjuvant or neoadjuvant che-

motherapy regimen for an individual is important because the right choice may

make the difference between cure and relapse. Results from traditionally

designed randomized clinical trials offer little guidance for individualized

treatment selection. These studies compare the activity of different treatments to

establish which is the most effective for the entire study population. This

approach ignores the fact that many patients are cured with earlier generation

adjuvant regimens and therefore are not well served by the administration of

longer, potentially more toxic, and more expensive second-or third-generation

combination therapies. These studies also cannot reveal whether some cancers

are particularly sensitive to a specific drug (or a combination of drugs) and

therefore can only be cured by that treatment. The most effective treatment for

an individual may or may not be the same regimen that is the most effective for

the whole population. These theoretical concerns and the increasing number of

adjuvant chemotherapy options, as well as the advent of new molecular ana-

lytical techniques, fuel a renewed interest in developing chemotherapy response

predictors that may lead to more personalized treatment recommendations.