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How does chemotherapy fit into cancer treatment?

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Precancerous growth in a human colon — cancer View through an endoscope of a polyp, a benign precancerous growth projecting from the inner lining of the colon.

Chemotherapy involves the administration of chemical compounds to destroy cancer cells by preventing them from multiplying. Unlike surgery or radiation therapy, which are often localized, chemotherapy drugs can disperse through the bloodstream to attack tumor cells throughout the body.1

In clinical practice, chemotherapy is utilized in four primary ways:
* As a primary treatment for localized cancer.1
* As a primary therapy for advanced cancer when no other alternatives exist.1
* As an adjunct therapy alongside surgery or radiation.1
* Administered directly to specific body regions or "sanctuaries" that the bloodstream cannot reach.1

Because cancer cells can develop drug resistance, combination therapy—using multiple drugs that target different phases of the cell cycle—is typically required to achieve a lasting response. While these treatments are essential, they can be toxic to healthy cells, leading to side effects such as nausea, hair loss, and bone marrow toxicity. It is a fundamental ethical principle in medicine to balance the efficacy of these life-saving treatments with the mitigation of their adverse effects to ensure patient well-being.12