Chemotherapy is a type of cancer treatment that uses drugs to destroy cancer cells. Chemotherapy works in a pattern of stopping or slowing the growth of cancer cells, which grow and divide quickly. But it can also harm quickly dividing healthy cells, such as those that lie in the mouth and intestines or cause hair to grow. Damage to healthy cells may cause side effects. Often, side effects get better or go away after chemotherapy is over. Chemotherapy is divided into two categories neoadjuvant and adjuvant chemotherapies. Neoadjuvant chemotherapy is a type which is delivered before surgery or radiotherapy, while adjuvant chemotherapy is delivered after the surgery or radiotherapy. Chemotherapy may be used to destroy cancer cells that have come back recurrent cancer or spread to other parts of the body metastatic cancer. Earlier, there used to be less number of chemotherapy drugs.