Chemotherapy for cancer of unknown primary

Chemotherapy (chemo) refers to the use of drugs to kill cancer cells or shrink tumors. Usually the drugs are given into a vein or taken by mouth. Once the drugs enter the bloodstream, they spread throughout the body. Because it reaches all parts of the body, chemo can sometimes be useful for cancer of unknown primary (CUP) as it may help kill cancer cells in places where they haven’t been found. Sometimes chemo is used to try to keep the cancer from growing or to relieve symptoms caused by the cancer. It may be able to help people live longer. If your doctor recommends chemo, you need to understand the goals of your treatment.

Chemo can have some side effects. These side effects will depend on the type of drugs given, the amount taken, and how long treatment lasts. Short-term side effects might include:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Low blood cell counts

Chemo often affects the blood-forming cells of the bone marrow, leading to low blood cell counts. This can cause:

• An increased chance of infection (from low white blood cell counts)
• Bleeding or bruising after minor cuts or injuries (from low blood platelet counts)
• Tiredness (from low red blood cell counts or other reasons)

Most side effects go away once treatment is over. Anyone who has problems with side effects should talk with their doctor or nurse because there are often ways to help. To learn more, see our document, Understanding Chemotherapy: A Guide for Patients and Families.