Clinical trials published in the 1980s taught us that in women with early stage breast cancer (stage 0, 1 and 2) that had a lumpectomy together with breast radiation therapy had the same survival rate as women who underwent a mastectomy. So the phrase Breast Conservation Surgery was coined.
Breast conserving surgery has 2 or 3 components, depending on the type of cancer. In women with DCIS (noninvasive or stage 0 cancer) there are two components: lumpectomy and radiation. In women with early-stage invasive cancer (stage 1 or 2) there are 3 components: lumpectomy, sentinel lymph node biopsy, and radiation.