Why is chemotherapy treatment boon for cancer patients?

Chemotherapy is a type of treatment that includes a drug, or combination of drugs, to treat cancer. The goal of chemotherapy is to stop, or slow the growth of cancer cells.
During World War 2, navel personnel who were exposed to mustard gas during military action were found to have changes in the bone marrowa cells that develop into blood cells,. This finding led researchers to investigate whether mustard agents could be used to halt the growth of rapidly dividing cells, such as cancer cells.Even though Paul Ehrlich was the first person to try chemotherapy in treating cancer, it is Sideny Farber who popularly known as the Father of Modern Chemotheraoy.
Research in this field eventually resulted in the introduction of many drugs known as chemotherapy drug that target cancer cells, and destroy them. These drugs are given in different combinations and different strengths, depending upon the type of cancer. Chemotherapy has proved to be a boon to cancer patients as it slows down the progression of disease.