There is a wide array of methods to diagnose cancer. As researchers learn more about the mechanisms of cancer, new diagnostic tools are constantly being developed and existing methods refined. If your primary care physician suspects cancer, he or she may order some tests to confirm the diagnosis. These tests can either be conducted by your physician or by oncologists at cancer centers like MD Anderson. No matter who makes the diagnosis, a second opinion by a cancer expert is strongly recommended. Some types of cancer, particularly lymphomas, can be hard to classify, even for an expert. Accurate identification of cancer allows oncologists to choose the most effective treatment. The most common diagnostic methods include:
A small tissue sample is surgically removed and examined under a microscope for the presence of cancer cells. Depending on tumor location, some biopsies can be done on an outpatient basis with only local anesthesia. If the tumor is filled with fluid, a type of biopsy known as a fine needle aspiration is used. A long, thin needle is inserted directly into the suspicious area to draw out fluid samples for examination.
A flexible plastic tube with a tiny camera on the end is inserted into body cavities and organs, allowing the physician to view the suspicious area. There are many types of scopes, each designed to view particular areas of the body. For instance, a colonoscope is used to detect growths inside the colon, and a laparoscope is used to examine the abdominal cavity.
Several techniques are used to produce an internal picture of the body and its structures. Types of imaging methods include:
X-rays are the most common way doctors make pictures of the inside of the body. Specialists can spot abnormal areas that may indicate the presence of cancer.
CAT scan (computerized axial tomography), uses radiographic beams to create detailed computerized pictures taken with a specialized X-ray machine. It is more precise than a standard X-ray, and provides a clearer image.
Magnetic Resonance Imaging (MRI) uses a powerful magnetic field to create detailed computer images of the body’s soft tissue, large blood vessels and major organs. MRI is an accurate but expensive process, and patients must lie completely still during the procedure for best results.
Ultrasound uses high-frequency sound waves to determine if a suspicious lump is solid or fluid. These sound waves are transmitted into the body and converted into a computerized image.
Some tumors release substances called tumor markers, which can be detected in the blood. A blood test for prostate cancer determines the amount of prostate specific antigen (PSA). Higher than normal PSA levels can indicate cancer. Recently, a blood test for ovarian cancer, known as CA-125, has become available. However, blood tests by themselves can be inconclusive, and other methods should be used to confirm the diagnosis.