Diagnosis

Tests and procedures used to diagnose carcinoma of unknown primary include:

• Physical exam. Your doctor might ask you about your signs and symptoms and examine the area that concerns you to gather clues about your diagnosis.
• Imaging tests. You might have imaging tests, such as X-ray, CT or MRI, to help with your diagnosis.
• Removing a sample of tissue for testing. To confirm that your symptoms are caused by cancer, your doctor may recommend a procedure to remove a sample of cells for lab testing (biopsy). This might be done by inserting a needle through your skin, or you might need an operation. In the lab, doctors will analyze the cells to see if they're cancerous and where they might have originated.

Tests to look for the original cancer

If initial tests find cancer cells that came from somewhere else in the body, you might have additional tests to look for the place where the cancer cells originated (primary tumor).

Tests might include:

• Physical exam. Your doctor will carefully examine your body to look for signs of cancer.
• Imaging tests. Your doctor might recommend imaging tests to look for signs of the original cancer. These tests might include CT and positron emission tomography (PET) scans.
• Blood tests. Blood tests that measure your organ function can give your doctor clues about whether cancer might be affecting your organs, such as your kidneys and liver. Blood tests that look for molecules that are sometimes produced by certain types of cancer (tumor markers) might provide more information for your diagnosis. Examples of tumor markers include prostate-specific antigen (PSA) for prostate cancer and cancer antigen (CA) 125 for ovarian cancer.
• Using a scope to examine the inside of the body. The doctor might use a long thin tube equipped with a camera to examine the inside of your body to look for signs of cancer. The scope might be passed through your mouth to examine the inside of your lungs, esophagus, stomach, liver or small intestine. To examine the colon and rectum, the scope can be inserted through your anus.
• Advanced lab testing. Doctors who specialize in analyzing blood and body tissue (pathologists) might run more-thorough tests of your cancer cells to gather more information for your diagnosis. Pathologists might use high-tech microscopes, special dyes and other technology, such as tests to look for changes in the genes and chromosomes of the cancer cells' DNA.

These tests might help your doctor locate the primary tumor where your cancer started. If the primary tumor is found, you would no longer have carcinoma of unknown primary. If your primary tumor can't be located despite testing, the results from these tests will help your doctor determine which treatments are most likely to help you.