Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each is classified by the type of cell that is initially affected. Cancer harms the body when damaged cells divide uncontrollably to form lumps or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream). Tumors can grow and interfere with the digestive, nervous, and circulatory systems and they can release hormones that alter body function.
If it's suspected that a patient has cancer, doctor may order certain cancer blood tests or other laboratory tests, such as an analysis of your urine or a biopsy of a suspicious area, to help guide the diagnosis. With the exception of blood cancers, blood tests generally can't absolutely tell whether a patient has cancer or some other noncancerous condition, but they can give doctor clues about what's going on inside the patient’s body.
Examples of blood and urine tests used to diagnose cancer include:
Complete blood count (CBC): This common blood test measures the amount of various types of blood cells in a sample of blood. Blood cancers may be detected using this test if too many or too few of a type of blood cell or abnormal cells are found. A bone marrow biopsy may help confirm a diagnosis of a blood cancer.
Urine cytology: Examining a urine sample under a microscope may reveal cancer cells that could come from the bladder, ureters or kidneys.
Blood protein testing: A test to examine various proteins in your blood (electrophoresis) can aid in detecting certain abnormal immune system proteins (immunoglobulins) that are sometimes elevated in people with multiple myeloma. Other tests, such as a bone marrow biopsy, are used to confirm a suspected diagnosis.
Tumor marker tests: Tumor markers are chemicals made by tumor cells that can be detected in your blood. But tumor markers are also produced by some normal cells in your body and levels may be significantly elevated in noncancerous conditions. This limits the potential for tumor marker tests to help in diagnosing cancer.
The best way to use tumor markers in diagnosing cancer hasn't been determined. And the use of some tumor marker tests is controversial also. Examples of tumor markers include prostate-specific antigen for prostate cancer, cancer antigen 125 for ovarian cancer, calcitonin for medullary thyroid cancer, alpha-fetoprotein for liver cancer and human chorionic gonadotropin for germ cell tumors, such as testicular cancer and ovarian cancer.
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