Compare Adjuvant Monotherapy With Endocrine or Accelerated Partial Breast Irradiation After Lumpectomy

The aim of this prospective study is to investigate quality of life and oncologic outcomes in low-risk elderly breast cancer patients randomized to adjuvant therapy with accelerated partial breast irradiation (APBI) alone or endocrine therapy alone after lumpectomy. The study population will include women age 65 years and older with low-risk tumor characteristics (tumor size \<2cm, grade 1-2, node-negative). APBI will consist of 5 fractions of radiation therapy delivered every other day to the lumpectomy cavity. Endocrine therapy will be chosen by the treating medical oncologist with an aim of 5 years duration, as tolerated by the patient. Quality of life outcomes will be measured at 1 year following lumpectomy and compared between groups. We hypothesize that the use of APBI may be superior in terms of quality of life when compared to endocrine therapy alone following lumpectomy while providing equivalent rates of disease control and overall survival. In this phase II study, we anticipate enrolling 90 women at N.C. Cancer Hospital in Chapel Hill, NC.