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Chemotherapy and cancer

Some key moments in the treatment's evolution

April 23, 2013

For decades, many cancer patients have depended on chemotherapy as part of the treatment for their disease. Chemotherapy is the use of drugs to stop cancerous cells from dividing and spreading throughout the body.

This is a look at how chemotherapy was borne out of chemical warfare and evolved into the treatments used today.

Origins in chemical warfare

During the Second World War, military doctors noticed that soldiers and sailors who had been exposed to mustard gas attacks experienced mutation in their bone marrow cells.

The U.S. Department of Defence enlisted pharmacologists to study whether mustard gas or other drugs used in chemical warfare could have medicinal uses.

In 1942, scientists had limited success using mustard nitrate — a compound related to mustard gas — to treat lymphoma. A patient's tumour shrank with treatment, but later expanded again.

These British soldiers were blinded by mustard gas in a German gas attack at Bethune, France, during the First World War. Doctors noticed that soldiers in the Second World War who were exposed to mustard gas experienced cell mutation in their bone marrow. (Three Lions/Getty Images)

Farber's advancements

Dr. Sidney Farber, a pathologist at Harvard University, used a drug called aminopterin to produce remission — the absence of cancerous cells — in children with a certain type of leukemia. His findings were published in 1948 and laid the groundwork for further cancer treatment research.

Aminopterin blocks a compound needed for cell replication; in Farber's trials, it prevented cancerous cells in the children's bone marrow from reproducing.

Farber's work is said to be the beginning of the modern chemotherapy era. He inspired trials with other drugs, and in 1956, a drug called methotrexate first produced remission in cancer that had metastasized (spread from its original location to other parts of the body).

Dr. Sidney Farber, right, has been called "the father of modern chemotherapy." (Public domain)

Combination therapy

Over time, new drugs were developed and approved to treat specific forms of cancer. Doctors also experimented with using more than one drug at a time; this technique is called "combination therapy" and was first successful in producing remission in children with leukemia in 1965.

Each of the different drugs used in combination therapy has its own specific function in the treatment.

Scientists say one benefit of combination therapy is through its use of multiple drugs. This prevents the cancerous cells from mutating and forming a resistance to a single drug.


Drug mixtures

The drugs used in chemotherapy treatments are cytotoxic — their purpose is to kill cells.

In their purest forms, these drugs would seriously harm a patient. Doctors decide on an appropriate dosage based on the patient's condition, body surface area and age. Children process drugs differently than adults.

The drugs must be watered down enough so they are safe for the patient, but not so weak they become ineffective as a treatment option.

In 2013, Cancer Care Ontario announced that more than 1,100 cancer patients had mistakenly received chemotherapy drugs that contained too much saline dilution solution.

The preparation of chemotherapy drugs has traditionally been done in hospitals, but some health centres have chosen to outsource the preparation to third-party companies that employ pharmacists.


Source: American Cancer Society, Cancer Research UK

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