How Is Cancer Diagnosed?

If your doctor suspects that you have cancer based on your symptoms or the results of a screening test or clinical examination, he or she will order certain diagnostic tests to find out whether you have abnormal cells and, if so, whether they are malignant (cancerous) or non-malignant (non-cancerous). If the tests show that the cells are malignant, you may need more tests to find out more about the cancer cells.

Many types of tests are used to diagnose cancer:

Biopsies -- A biopsy is usually the only way to tell for sure whether you have cancer or not. The doctor cuts out a small piece of tissue (a groupf of similar cells) and sends it to a laboratory to be studied. A pathologist (a doctor who specializes in diagnosing diseases) looks at the tissue under a microscope to see whether it has cancerous cells.

Imaging tests -- These tests or evaluation procedures produce pictures of areas inside the body. They include x-rays, like mammograms, computed tomography (CT or CAT) scans, and magnetic resonance imaging (MRI) scans. Other common imaging tests include ultrasound and positron emission tomography (PET) scans.

Laboratory tests -- A laboratory technician measures substances in the blood or urine that can indicate how advanced the cancer is or other features of your cancer.

Genomics tests -- Polymerase chain reaction (PCR), fluorescent in situ hybridization (FISH), and other genomics tests (tests of genes and their functions) can find mutations (unusual changes) in certain genes that are known to cause cancer.