Cancer of Unknown Primary Treatment

Cancer of Unknown Primary Treatment

Medical oncologist Eileen O’Reilly speaks to patient.

Medical oncologist Eileen O’Reilly treats cancer of unknown primary with chemotherapy and other drugs.

At Memorial Sloan Kettering, care for cancers of unknown primary is managed by a team of doctors. Each member specializes in using chemotherapy, surgery, radiation therapy, or other therapies to treat cancers of unknown primary. This collaborative approach ensures that every person we care for gets the treatment or combination of treatments that best address their condition.

Because cancer of unknown primary is by definition a cancer that has spread from a primary site, the disease is already at an advanced stage by the time it is diagnosed. Although there are no standard treatments for cancers of unknown primary, chemotherapy is usually the main treatment.


Chemotherapy is the most common treatment for people with cancer of unknown primary. Given by IV or as a pill, chemotherapy destroys cancer cells throughout the body. This includes areas where cancer may not have been found. Chemotherapy is used to shrink tumors and relieve the symptoms caused by cancer. In rare cases, it can eliminate tumors so that no further treatment is necessary.

When possible, doctors at Memorial Sloan Kettering choose a chemotherapy regimen that is effective in treating the organ or part of the body where we suspect the cancer began. Even when the primary site or part of the body cannot be identified, we customize the chemotherapy regimen for each person we care for after determining the type and appearance of the cancer cells, where the cancer has spread, and the individual’s overall health.


Surgery is often the treatment of choice for people with a tumor that is confined to the organ where it began. But because cancer of unknown primary has already spread, surgery does not usually cure the cancer.

When a tumor of unknown primary is found in only one organ or lymph node, or if there are specific symptoms related to the site of the tumor, our doctors may recommend surgery. If the cancer is suspected to have begun in the breast, a mastectomy (surgical removal of the breast) may be required to ensure that all of the breast cancer cells have been removed. When surgery is used to treat cancer of unknown primary, it is usually followed by chemotherapy or radiation therapy to eliminate any cancer cells that may remain.

Radiation Therapy

Radiation therapy is only used to control tumors that cannot be surgically removed or when cancer of unknown primary spreads to the spine and interferes with neurologic function.

Targeted Therapy and Immunotherapy

Genetic testing using MSK-IMPACT™ can help doctors identify people with tumors that are likely to respond to immunotherapy or targeted therapies through a clinical trial.

Request an Appointment

Call 800-525-2225
Available Monday through Friday, to (Eastern time)