Chemotherapy treatment uses medicine to weaken and destroy cancer cells in the body, including cells at the original cancer site and any cancer cells that may have spread to another part of the body. Some people are offered chemotherapy before surgery. It may be used to slow the development of rapidly growing cancers or to shrink larger cancers. In breast, cancer chemotherapy is typically used to treat patients with locally advanced or metastatic breast cancer. Your medical oncologist may recommend chemotherapy before you undergo breast cancer surgery or after surgery. The side effects of breast cancer due to chemotherapy drugs, such as nausea, vomiting, fatigue, sore mouth, diarrhea, constipation and decreased blood counts. These side effects can impact your ability to tolerate treatments, maintain a healthy diet, stay active and enjoy a good quality of life. When treating early-stage breast cancer, it's fairly common for chemotherapy to be given after surgery, as soon as you recover and In early-stage breast cancer, standard chemotherapy regimens lower the risk of cancer coming back. In some cases, chemotherapy is given before surgery to shrink cancer so that less tissue has to be removed.