What exactly is neoadjuvant chemotherapy?

Before surgery: Neoadjuvant chemotherapy simply means chemotherapy given before surgery to remove a tumor. It is usually given that way in the hope that it will shrink the tumor, making surgery easier. Adjuvant chemotherapy is given after surgery.

Chemo before surgery: When chemotherapy is given before surgery it's called neoadjuvant. When chemo or radiation is given in addition to and after surgery it's called adjuvant. It is only describing the order of the treatments.