Carcinoma of Unknown Origin

Diagnosis

To help determine the best treatment options for patients with carcinoma of unknown origin, Mayo Clinic physicians use the latest diagnostic techniques. During the diagnostic process, physicians try to determine where the cancer began so they can formulate the most effective treatment plan.

Medical History

A first step toward diagnosing carcinoma of unknown origin is an in-depth interview with the patient. During the interview, the physician records details about the patient's symptoms, when they first appeared, and therapies used to date. Often, clues obtained from the interview guide further patient evaluations. Mayo physicians also focus on patient symptoms such as pain, so they can devise appropriate therapies designed to minimize (palliate) cancer symptoms.

Physical Examination

Once the physician has the patient's medical history, the next step is a physical examination. During this comprehensive examination the physician focuses on areas of patient concern, including lumps, swellings, and areas of pain.

Laboratory Testing

The physician will order blood tests, urine analyses, tumor marker tests, stool evaluations, and other laboratory tests tailored to each patient's cancer and symptoms. The tests will help to comprehensively evaluate the patient's condition, define areas of concern, and establish the cancer's organ of origin.

Imaging Studies

Specialists at Mayo Clinic use high-resolution imaging studies to diagnose carcinoma of unknown origin. These studies may include:

• X-rays generate two-dimensional views of the body to help physicians locate abnormalities.
• Ultrasound uses high-frequency sound waves to create images of the body that identify cancer sites. A technician places a wandlike device (transducer) on the surface of the abdomen or other body parts and monitors the image on the screen.
• Computed tomography (CT) scans generate two-dimensional images of the chest, abdomen, pelvis, or other body parts to better define the extent of cancer spread. New technology available at Mayo Clinic enables three-dimensional reconstruction of the CT images.
• Magnetic resonance imaging (MRI) technology uses magnetic fields and radio waves to create two- and three-dimensional views used to identify small abnormalities in the body.
• Positron emission tomography (PET) scans use radioactive materials to identify metabolically active tissues, which may be cancerous.
• Other nuclear medicine scans such as bone, octreotide, and thyroid scans may also be used to help define the locations of tumor spread.

Biopsy

To confirm a suspected case of carcinoma of unknown origin, a physician may remove and analyze a small piece of the suspected tumor (biopsy). Depending upon the location of the tumor, tissue may be collected during an endoscopic (scope) exam, by using a needle (often under ultrasound or CT guidance), or by surgically removing a sample of the tumor. Experienced pathologists examine the tissue under a microscope and use an array of specialized tissue stains (immunohistochemistry) to define the organ of the cancer's origin. Carcinoma of unknown origin can arise in many different types of cells. Identifying the cell types in the laboratory provides vital clues that help to ensure the best treatment for each patient.