With the increasingly early diagnosis of breast cancer and the advent of breast 
tumor subtyping, the need for determining which patients need adjuvant therapy 
has become more pressing and more complex. While clinical and pathologic 
features to predict benefit are valuable, the use of molecular techniques to 
better determine which tumors will benefit from chemotherapy is expected to 
further improve outcomes, reduce long-term complications, and provide 
cost-effective care. We will review the primary tools in clinical use: 
Adjuvant!, Oncotype DX, and MammaPrint as well as intrinsic subtypes and the 
plans for their further assessment in the clinical trial setting. The expected 
benefit from these models are that treatment recommendations for women with 
early-stage breast cancer will become more individualized and thereby 
appropriate by combining standard clinicopathologic and molecular features. This 
concept is currently being evaluated in multiple well-designed clinical trials.