These markers, though useful, have many limitations. It must be appreciated that many patients with cancer will have results within the “normal” range. For most of these markers there are also non-malignant conditions that can cause elevation.
Alpha Fetoprotein (AFP)
A useful marker for some types of testicular cancer, germ cells tumours and primary liver cancer. Elevated AFP levels are occasionally found with some cases of carcinoma of pancreas, stomach, colon and lung. The level also rises in some non-malignant liver diseases and inflammatory bowel diseases. The test has a confirmed role in the early detection of open neural tube defects in pre-natal screening for pregnant women, such as spinal bifida and anencephaly.
The majority of normal people have a level less than 5.0 ug/L though this may be raised in smokers. CEA is non-tissue specific as an elevated level may also be found in a variety of cancers such as cancers of the gastrointestinal tract, pancreas, lung, breast and liver. A persistently raised CEA is generally indicative of residual or recurrent cancer.
This is a preferred test for pancreatic carcinoma. It may also be increased with other adenocarcinomas such as lung, gastic, biliary and colon. Occasionally, elevated levels are found in various benign and inflammatory diseases of the gastrointestinal tract, liver and in mucoviscidosis. A continuous rise in CA19-9 level in the absence of, or in the presence of static, signs of inflammation or cholestasis is strongly suggestive of malignant pancreatic disease.
CA125 is produced by many ovarian cancers. Markedly elevated levels are sometimes found with various benign gynecologic tumours and also with inflammatory processes involving the adnexa. Slight elevations of this marker are also found during pregnancy, in various autoinunune diseases, and in hepatitis, chronic pancreatitis, and in cirrhosis of the liver. Gastrointestinal tumours, bronchial carcinoma, and breast carcinoma can also show in some cases considerable elevations of CA125.
PSA is produced in the prostate, and it is a useful screening test of prostatic cancer. Considerable elevations of serum PSA are sometimes found in prostatic hypertrophy and also in inflammatory conditions of the prostate. PSA levels are useful for monitoring of response to treatment for prostate cancer and for monitoring patients with benign prostatic hypertrophy so as to detect the presence of prostatic carcinoma as early as possible.