RT Book, Section A1 Irvin Jr, William A1 Amos, Keith A2 Kuerer, Henry M. SR Print(0) ID 6416696 T1 Chapter 83. Selection of Patients for Therapy T2 Kuerer's Breast Surgical Oncology YR 2010 FD 2010 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-160178-8 LK accesssurgery.mhmedical.com/content.aspx?aid=6416696 RD 2024/04/18 AB Initial observational studies of the natural history of breast cancer (untreated) viewed all breast cancers as the same, causing death a median of 2.7 years after presentation.1 Similarly, initial treatment trials2-4 viewed breast cancer as a homogeneous disease with no consideration of possible biological differences. Fortunately, in the 1960s, breast cancer heterogeneity was beginning to be recognized and included such factors as tumor size, the number of tumor-involved lymph nodes,5-7 and later the influence of estrogen receptor (ER) and progesterone receptor (PR).8-10