Differences between Chemotherapy and Radiation Therapy
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Chemotherapy vs. radiation therapy[edit]
Chemotherapy and radiation therapy are medical treatments used to treat cancer, either as primary therapies or to assist other treatments like surgery. The main distinction between these modalities is the scope of their application. Chemotherapy is a systemic treatment that affects the entire body, whereas radiation therapy is a localized treatment targeting a specific area.
Comparison table[edit]
| Feature | Chemotherapy | Radiation therapy |
|---|---|---|
| Primary reach | Systemic (entire body) | Localized (targeted area) |
| Mechanism | Uses drugs to stop cell division | Uses high-energy rays to damage DNA |
| Administration | Oral pills or intravenous (IV) injection | External beams or internal implants |
| Common side effects | Nausea, hair loss, and fatigue | Skin changes and site-specific inflammation |
| Treatment goal | Kill cells that have spread (metastasis) | Shrink tumors or eliminate remaining cells |
| Frequency | Often administered in cycles with rest periods | Typically given daily over several weeks |
Chemotherapy[edit]
Chemotherapy involves the use of cytotoxic drugs to kill cancer cells. These medications enter the bloodstream and travel to nearly all parts of the body. This systemic reach allows chemotherapy to target cancer cells that may have broken away from the original tumor and moved to other organs or tissues.[1]
The drugs work by interrupting the cell cycle. Cancer cells generally grow and divide faster than healthy cells, which makes them more sensitive to these chemicals. However, chemotherapy also impacts healthy cells that divide quickly. This includes cells in the hair follicles, the lining of the digestive tract, and the bone marrow. Damage to these healthy cells leads to systemic side effects such as hair thinning, mouth sores, and a decrease in white blood cell counts.[2]
Radiation therapy[edit]
Radiation therapy uses ionizing radiation, such as X-rays or protons, to destroy malignant cells. Unlike chemotherapy, radiation is directed at a precise location. A machine called a linear accelerator typically delivers beams from outside the body, known as external beam radiation. Another method, brachytherapy, involves placing a radioactive source directly inside or near the tumor.[3]
The goal of radiation is to create breaks in the DNA of the cancer cells. This prevents the cells from reproducing and causes them to die over time. Because the radiation is targeted, side effects are usually limited to the part of the body being treated. For instance, radiation to the head may cause hair loss in that specific area, but radiation to the pelvis will not. Patients often experience skin irritation at the entry site, similar to a sunburn, and localized fatigue.[4]
Combined treatment[edit]
Oncologists may use both treatments for a single patient. In some cases, chemotherapy is used to shrink a tumor before radiation or surgery. In others, "chemoradiation" is used, where low doses of chemotherapy drugs are given to make the cancer cells more sensitive to radiation. The choice of treatment depends on the cancer type, its stage, and the patient's overall health.
