Chemotherapy is the use of chemotherapy drugs, chemotherapy treatments, chemotherapy agents, chemotherapy medications to kill cancer cells. In most cases chemotherapy for cancer consists of a regiment of chemotherapy agents injected intravenously, chemotherapy medication given orally or by injection, or inhaled as a powder. The most common chemotherapy drugs are gemcitabine and cisplatin.

The goal of chemotherapy is to kill any remaining tumor cells that may have been left after surgery and/or radiation therapy. It is typically used for curative intent. Chemotherapy may also be used for palliative intent – that is to control symptoms or side-effects from other treatments such as radiation therapy or as an adjuvant therapy which does not cure but helps to prevent recurrence.

In chemotherapy, cytotoxic drugs are used to kill cancer cells and stop them from dividing so they cannot spread. In a healthy cell, the process of normal cellular growth and division is tightly controlled by chemical signals that tell each new cell when or where it should grow. Some chemotherapy agents interfere with part of this process called mitosis (cell division). These can either be natural substances produced by the body itself which have anti-cancer properties or plant-, fungus- or bacteria-derived chemicals known as chemotherapy agents.