This is very unlikely. Sometimes it appears to cure women of breast cancer even if it doesn't. This happens if most of the cancer cells are killed and those remaining take so long to grow that the woman dies of something else before the metastatic cancer is large enough to find. Unfortunately, this is not common. Aggressive cancers usually grow quickly and reappear in a just few years.
Chemotherapy helps people live longer.
Disease-free survival is the time after surgery when cancer cannot be found in the body. Total survival is the length of time after surgery that someone lives, and includes time with and without known return of the cancer. Chemotherapy increases both, but it increases disease-free survival time more than total survival time. Studies compare groups of people who have received chemotherapy to those who have not. It is very important that a woman learn the absolute differences in survival, not just the percentage increase when deciding about chemotherapy or other treatments.