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Radiation therapy
Source: Carcinoma of Unknown Primary Treatment (PDQ®)–Patient Version, National Cancer Institute.
Source updated: December 17, 2021 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary. Independent clinical review is pending.
Context: Treatment Option Overview / Four types of standard treatment are used:
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy:
External radiation therapy uses a machine outside the body to send radiation toward the area of the body with cancer. Certain ways of giving radiation therapy can help keep radiation from damaging nearby healthy tissue. This type of radiation therapy may include the following:
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External radiation therapy uses a machine outside the body to send radiation toward the area of the body with cancer. Certain ways of giving radiation therapy can help keep radiation from damaging nearby healthy tissue. This type of radiation therapy may include the following:
Intensity-modulated radiation therapy (IMRT): IMRT is a type of 3-dimensional (3-D) radiation therapy that uses a computer to make pictures of the size and shape of the tumor. Thin beams of radiation of different intensities (strengths) are aimed at the tumor from many angles. This type of external radiation therapy causes less damage to nearby healthy tissue and is less likely to cause dry mouth, trouble swallowing, and damage to the skin.
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Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer.
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The way the radiation therapy is given depends on the type and stage of the cancer being treated. External and internal radiation therapy are used to treat carcinoma of unknown primary.
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Preserved source evidence · Independent clinical review pending · Not medical advice