ERBB2 and breast cancer: Younger age at diagnosis, use of aromatase inhibitors (versus tamoxifen), larger tumor size, positive lymph node involvement, higher tumor grade, negative progesterone receptor status, positive HER2 status, chemotherapy, radiotherapy, having first-degree relatives dying from breast cancer, higher income was associated with a higher likelihood to extend therapy after finishing their 5-year adjuvant hormone therapy in the age-adjusted model.