Chemotherapy
Chemotherapy is cancer treatment that uses medicines to kill cancer cells, slow their growth, or reduce the chance that cancer returns. It can be used alone or with surgery, radiation therapy, immunotherapy, targeted therapy, hormone therapy, and supportive care.
What chemotherapy is
Chemotherapy is a group of cancer treatments that use drugs to damage or kill cancer cells. Many chemotherapy drugs are cytotoxic, meaning they harm cells that are dividing or copying DNA. Because cancer cells often divide quickly, chemotherapy can be effective, but it can also affect healthy fast-growing cells.
How it works
Different chemotherapy drugs interfere with different cell processes. Some damage DNA. Some block DNA copying. Some disrupt the structures cells need to divide. Others affect metabolic pathways that growing cells rely on. A treatment plan may combine drugs with different mechanisms so cancer cells are attacked in more than one way.
Goals of treatment
Chemotherapy can have different goals. Curative chemotherapy aims to eliminate cancer when that is realistic. Adjuvant chemotherapy is given after another treatment, such as surgery, to reduce recurrence risk. Neoadjuvant chemotherapy is given before surgery or radiation to shrink a tumor. Palliative chemotherapy aims to slow cancer, relieve symptoms, or improve quality of life when cure is not the goal.
How chemotherapy is given
Chemotherapy may be given through an IV infusion, injection, pill, capsule, topical medicine, or direct delivery into a body cavity, artery, bladder, spinal fluid, or other region. The route depends on the drug, cancer type, treatment goal, and safety concerns. Some people receive treatment in cycles, with recovery time between doses.
Why cycles matter
Chemotherapy is often scheduled in cycles because both cancer cells and healthy tissues need time between treatments. The timing is designed to keep pressure on cancer while allowing bone marrow, digestive tissues, skin, and other normal cells to recover enough for the next dose. Delays or dose changes may be needed if side effects become unsafe.
Side effects
Side effects depend on the drugs used, dose, schedule, cancer type, and the person's overall health. Common issues can include fatigue, nausea, vomiting, hair loss, mouth sores, appetite changes, diarrhea, constipation, infection risk, anemia, bruising, nerve symptoms, fertility effects, or changes in thinking and memory. Supportive medicines and monitoring can reduce some harms.
Combination treatment
Chemotherapy is often part of a larger treatment plan. It may be combined with surgery to remove a tumor, radiation therapy to treat a local area, immunotherapy to help immune responses, targeted therapy aimed at molecular features, or hormone therapy for hormone-sensitive cancers. The best combination depends on cancer type, stage, tumor biology, and patient goals.
Resistance and response
Some cancers respond strongly to chemotherapy, while others respond partly, briefly, or not at all. Resistance can happen when cancer cells repair drug damage, pump drugs out, change drug targets, grow more slowly, or evolve under treatment pressure. Response is tracked with symptoms, exams, imaging, blood tests, pathology, and tumor markers when appropriate.
Supportive care
Chemotherapy care includes more than the drug itself. Patients may need anti-nausea medicine, infection prevention, blood-count monitoring, nutrition support, pain control, fertility counseling, mental-health support, transportation help, and clear instructions about when to call a care team. Good supportive care can make treatment safer and more tolerable.
Why it matters
Chemotherapy matters because it remains one of the main tools of cancer treatment even as newer approaches expand. It can cure some cancers, extend life for others, shrink tumors before local treatment, reduce recurrence risk, and relieve symptoms. Understanding chemotherapy helps readers see both its power and its limits without reducing cancer care to one kind of medicine.