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Diagnostic Evaluations

Tumor markers

Tumor markers are substances in the body that are produced in much higher quantities when cancer or certain benign conditions are present. The substances may be found in the blood, urine, stool or tumor tissue. Most of these substances are proteins, but sometimes gene expression patterns and DNA changes are used as tumor markers, as well.

Because an elevated tumor marker doesn’t necessarily indicate cancer, tumor markers cannot be used alone to diagnose cancer. Generally, tumor marker measurements are used in combination with other tests, such as biopsies.

Tumor marker tests used to diagnose cancer include those listed below.

CA-125 test

A CA-125 test measures the amount of the cancer antigen 125 (CA-125) in a person’s blood. CA-125 is a protein that is a biomarker or tumor marker. The protein is found in higher concentration in cancer cells, particularly ovarian cancer cells.

Cancer types that may cause higher-than-normal levels of CA-125 include:

Cancer that has spread to the peritoneum, the abdomen’s lining, may also cause higher-than-normal levels of CA-125.

The CA-125 test helps doctors:

  • Monitor ovarian cancer and other cancers to determine whether they are responding to treatment
  • Monitor patients with ovarian and other cancers post-treatment to check for cancer recurrence
  • To an extent, screen for ovarian cancer in women who are at high risk for developing the disease

For the test, a nurse or other clinician obtains a sample of the patient’s blood. The sample is sent to a laboratory for analysis to determine whether the level of CA-125 is abnormal.

Patients who have been previously treated for ovarian cancer who have elevated CA-125 levels may have a cancer recurrence. However, additional testing and surgery may be necessary to confirm a recurrence.

It’s important to note that conditions other than cancer may cause higher levels of CA-125, including:

  • Uterine fibroids
  • Endometriosis
  • Lupus
  • Liver disease
  • Pancreatitis
  • Pelvic inflammatory disease
  • The first trimester of pregnancy
  • Menstruation

Additionally, cancer medications, recent abdominal surgery or radioactive scans may alter CA-125 levels.

Prostate-specific antigen test

A prostate-specific antigen (PSA) test measures the level of PSA in the blood. The prostate gland produces PSA, a protein that at an elevated level may be a sign of prostate cancer. A high PSA reading also may indicate noncancerous conditions, such as inflammation of the prostate (prostatitis) and enlargement of the prostate (benign prostatic hyperplasia).

Men who have symptoms associated with prostate cancer may have a PSA test along with a digital rectal exam (DRE). These symptoms include burning or pain during urination, loss of bladder control, painful ejaculation, and swelling in the legs or pelvic region. For the test, a clinician takes a sample of blood and sends it to a lab for analysis.

In the past, a PSA reading of 4 ng/mL and below was considered normal. Men with a reading above 4 ng/mL were considered likely to have prostate cancer and would have a biopsy to confirm the cancer’s presence. According to the National Cancer Institute, research now shows that men with prostate cancer may have a low PSA level, while men without prostate cancer may have a high level. One in four men with an elevated PSA level actually has prostate cancer. However, an increase in PSA level over time may indicate prostate cancer. That’s why some men with a high PSA level may be monitored under active surveillance, which involves PSA testing at regular intervals.

BRCA1 and BRCA2

Mutations in the BRCA1 and BRCA2 (breast cancer 1 and breast cancer 2) genes are commonly used as tumor markers for breast and ovarian cancer. BRCA mutations may be inherited and are associated with an increased risk of developing cancer. The BRCA gene test is typically recommended for people with a personal or family history of cancer, or for those with a specific type of breast cancer. The test generally isn’t performed on those with an average risk for breast or ovarian cancer.

A positive result on a BRCA gene test doesn’t necessarily mean a person will develop cancer. It only means the person carries one of the gene mutations. Similarly, a negative result on the test doesn’t mean a person will not develop cancer. It only means that those specific mutations are not present.