Tuesday, September 25, 2007 Dumaguing: Blood tests to diagnose cancer By Dr. Victor Dumaguing To Your Health
IF SIGNS and symptoms suggest you may have cancer, blood tests will be done to examine the number and type of blood cells and to measure levels of certain blood chemicals.
Blood cell counts and blood cell examination: Changes in the numbers of different blood cell types may suggest that CUP (Cancer of Unknown Primary Origin) has spread to bones and replaced much of the normal blood-producing marrow cells. If there is anemia (lower than normal amount of red blood cells), that might mean there is intestinal bleeding caused by the cancer and point to somewhere in the intestine as the site of its origin.
Liver function tests: Abnormal liver function tests in a person with CUP suggest cancer may be present in the liver. The cancer may have started in the liver or may have spread from another part of the body. Hepatitis virus infection can cause liver cancer. A test for hepatitis B and C viruses might be helpful. If the test shows that you have the virus, doctors would suspect that the cancer may have started in the liver. Serum tumor markers: Some types of cancer release certain substances into the bloodstream. If these substances are present in blood samples of CUP patients, they can provide valuable clues to the origin of the cancer. For example, high prostate-specific antigen (PSA) levels suggest that a CUP started in the prostate gland. High CA-125 levels suggest ovarian cancer. High levels of human chorionic gonadotropin (HCG) suggest a germ cell tumor, a type of cancer that can begin in the testicles, ovaries, the mediastinum (area in front of the heart and behind the breastbone), or the retroperitoneum (area behind the intestines). Alpha-fetoprotein (AFP) is produced by some germ cell tumors as well as by hepatocellular carcinoma (liver cancer).
Paracentesis or thoracentesis: In patients with a collection of fluid inside the abdomen (ascites) or fluid in the chest (pleural effusion), samples of the fluid can be removed through a needle for examination under the microscope. Paracentesis is the medical term for removing abdominal fluid. Thoracentesis refers to removing fluid from the chest cavity. These procedures are done to see if the fluid contains cancer cells and, if so, to determine the type of cancer that is present.
Bone marrow aspiration and biopsy: In bone marrow aspiration, a needle and syringe are used to remove small amounts of liquid bone marrow. For a bone marrow biopsy, a larger needle is used to remove a cylinder of bone marrow, about 1/16-inch and 1-inch long. Both samples are usually taken from marrow at the back of the pelvis after numbing the area with a local anesthetic.
