Radiation Therapy for a Cancer of Unknown Primary

Radiation therapy can be used to treat a cancer of unknown primary (CUP). However, the goal of radiation therapy may change based on your situation. 

For some cancers that have not spread too far from where they started, radiation therapy can be used alone or with other treatments, such as surgery, to try to cure the cancer. When cancer has spread to many parts of the body, radiation can be used to relieve symptoms. It can help with symptoms such as pain, bleeding, trouble swallowing, intestinal blockage, compression of blood vessels or nerves by tumors, and problems caused by metastases to bones.

Types of radiation therapy used for cancers of unknown primary (CUP)

Radiation therapy uses high-energy rays (or particles) to kill cancer cells or slow their rate of growth.

• External beam radiation therapy focuses a beam of radiation from a device into the cancer.
• Internal radiation therapy (brachytherapy) surgically places radioactive material, usually in the form of tiny, seed-like packets, directly into or as close as possible to the cancer.

Internal radiation therapy lets your doctor give a dose of radiation to a smaller area and in a shorter time than is possible with external radiation treatment. Sometimes, both internal and external beam radiation therapies are used together.

Possible general side effects from radiation treatment for cancers of unknown primary (CUP)

Side effects of radiation depend on where the radiation is aimed or placed and the dose given, and may include the following:

• Fatigue (feeling tired)
• Loss of appetite
• Low blood counts
• Skin changes in areas getting radiation, ranging from redness to blistering and peeling. These can often be treated with different types of skin balms or lotions.
• Hair loss at the site where the radiation is aimed

For information on side effects of radiation given to specific areas of the body, see Radiation Therapy Side Effects.

Most of these side effects go away after treatment ends, but some are long-term and may never go away completely.

If chemotherapy is given along with radiation, the side effects are often more severe.

There are ways to relieve many of these side effects, so it’s important to tell your cancer care team about any changes you notice.