Chemotherapy is a form of cancer treatment that uses powerful drugs to kill rapidly growing cancer cells in the body. It is one of the most commonly used systemic treatments for various types of cancers. Unlike surgery or radiation therapy, which are localized treatments, chemotherapy affects the whole body and can target cancer cells that have spread (metastasized) to distant organs. It can be used alone or in combination with other treatments like surgery, radiation, targeted therapy, or immunotherapy.

The decision to use chemotherapy depends on several factors including the type and stage of cancer, the patient's overall health, and treatment goals. It may be given before surgery (neoadjuvant chemotherapy) to shrink tumors, after surgery (adjuvant chemotherapy) to kill any remaining cancer cells, or as the main treatment in cases where surgery is not possible. Chemotherapy is also used to relieve symptoms and improve quality of life in advanced cancer cases (palliative chemotherapy).

Chemotherapy drugs work by interfering with the cancer cells' ability to grow and divide. Since they also affect normal, fast-growing cells such as those in the bone marrow, hair follicles, and digestive tract, side effects are common. These can include fatigue, nausea, vomiting, hair loss, loss of appetite, lowered immunity, and increased risk of infections. However, modern supportive medications have greatly improved the management of these side effects, making chemotherapy more tolerable for patients.

The treatment is usually delivered in cycles, with rest periods in between to allow the body to recover. It can be administered intravenously (through a vein), orally (as pills), or through injections, depending on the specific drugs and the cancer type. The duration and number of cycles vary with each individual case, and patients are closely monitored through blood tests and scans to assess response and adjust treatment if needed.

Chemotherapy remains a critical part of comprehensive cancer care. While it can be challenging, many patients benefit significantly from it in terms of survival and quality of life. The involvement of a dedicated oncology team—medical oncologists, oncology nurses, pharmacists, and support staff—ensures safe administration, side-effect management, and emotional support throughout the treatment journey.