Dear gmachris: Factors that determine a recommendation of chemotherapy for localized disease include the type of tumor, grade of tumor, size of tumor, whether there are any lymph nodes involved, ER/PR status (hormone receptor status), HER2 status (whether the HER2 antigen is expressed on the tumor), age and health of the patient. Radiation therapy is generally recommended in the case of lumpectomy. Hormone therapy is usually recommended when the hormone receptors are positive.
Here's the national guidelines for treatment for breast cancer in the U.S.:
http://www.nccn.org/patients/patient_gls/_english/_breast/3_work-up.asp