PSA: Is it a good prostate cancer marker?

Prostate specific antigen (PSA) is a protein produced by cells in the prostate glands. Thus only male has PSA. PSA has been widely used as a screening tool for prostate cancer.

   Location of prostate gland

It is still controversial whether PSA is suitable to be used to screen for prostate cancer. Studies have shown that while most prostate cancer sufferers have raised PSA level, this test is somehow not specific. This means that the false positive rate is quite high. Even though one has high level of PSA, he may not have prostate cancer.

There are a few recognized causes for raised PSA, all of them are associated with irritation of the prostate:

1. Benign Prostatic Hyperplasia – enlarged prostate due to aging
2. Prostatitis – inflammation of prostate (can be infection or non-infection)
3. Prostate cancer
4. Recent ejaculation (avoid testing PSA in 48 hours)
5. Recent prostate biopsy (avoid testing PSA in 6 weeks)
6. Recent prostate surgery
7. Recent digital rectal examination (avoid testing PSA in 1 week)
8. Recent urinary cathetherization
9. Urinary retention
10. Recent rigorous exercise esp bicycle riding

 

   Benign Prostatic Hyperplasia

Generally the cut off point for PSA value is set at 4.0ng/ml. Since PSA level is age-dependent as prostate gland will increased in size with age, some authorities suggest to modify it according to age.

Age	“Normal” PSA (ng/ml)
40-49	<2.5
50-59	<3.5
60-69	<4.5
70-79	<6.5

Although PSA <4.0ng/ml is widely considered as normal, there is still a possibility of prostate cancer (about 20% chance) in these people. PSA between 4.0 and 10.0ng/ml is considered borderline (25% chance of prostate cancer), while PSA >10.0ng/ml has higher risk (67% chance of prostate cancer).

Since the false positive rate is quite high, PSA may not be a good cancer marker as it can cause unnecessary further investigation and anxiety. Digital rectal examination (a finger is inserted into rectum) is usually done to feel for abnormality in the gland. For men with higher risk of prostate cancer such as old age and positive family history, further test such as prostate ultrasound and biopsy may be needed. For those with low risk, other causes of raised PSA should be looked for and treated accordingly. The PSA level can be repeated after 6-12 weeks to see the trend. If it continues to rise significantly, then further investigation is warranted. Another blood test that can be done is free/bound PSA ratio. More free PSA compared to bound PSA is good news. The standard PSA test is total PSA (free + bound).

Whether you should have your PSA checked depends on you. One one hand it may save your life by detecting prostate cancer early, on the other hand it may cause unnecessary anxiety, loss of money and complication from further investigation.

Fatty Liver: please check ALT

Fatty liver is just accumulation of excess fat in the liver. It can be primary or secondary.

Primary (cause unknown)

• NAFLD (Non-Alcoholic Fatty Liver Disease)

Secondary (cause known)

• Alcohol
• Hepatitis B
• Hepatitis C
• Drugs-induced
• Wilson's disease
• Autoimmune hepatitis

    Fat cells (white) in the liver

NAFLD is a spectrum of diseases ranging from

• Simple fatty liver (steatosis)
• Fatty Liver with inflammation & fibrosis (NASH – Non-Alcoholic Steato-Hepatitis)
• Severe liver scarring/fibrosis (cirrhosis)

    Note the changes in liver size

The cause of NAFLD is not clearly known. However it is believed to be associated with insulin resistant, a condition that causes metabolic syndrome and type 2 diabetes mellitus. So, you probably have NAFLD if you have the following:

• Obesity/overweight
• Diabetes mellitus (type 2)
• High LDL-cholesterol
• Low HDL-cholesterol
• High triglycerides

Fatty liver has no specific symptoms in early stages. It is usually first suspected when people do blood test for whatever reason and find that their ALT (alanine transaminase) is raised. There are a few causes of raised ALT, which represent liver inflammation/injury. Doctors will rule out those causes such as drug-induced (esp cholesterol medicine) and viral hepatitis etc. If nothing can be found, ultrasound of the liver should be done to look for fatty liver. Ultrasound is a cheap, simple and accurate (though not 100%) method to diagnose fatty liver.

    Fatty liver on ultrasound, "more white" compare to the kidney

When fatty liver is confirmed via ultrasound, the next step is to find the cause of fatty liver. As mentioned earlier, the secondary causes such as alcohol, viral hepatitis etc need to be ruled out. If a cause of fatty liver is identified, we can treat that condition accordingly. But if no cause can be found, then we can call it NAFLD.

• NAFLD with normal ALT = simple fatty liver = harmless
• NAFLD with raised ALT = NASH = slight risk of progression to liver cirrhosis & subsequently liver cancer

The risk of liver cirrhosis in NASH is not well established, should be around 10%. However, it takes many years (>20 years) to progress from NASH to cirrhosis. Compared to NASH, cirrhosis usually occurs earlier in fatty liver caused by alcohol and hepatitis.

If your fatty liver is due to alcohol, you have to reduce or stop drinking. If it is due to viral hepatitis, you may need anti-viral treatment. Though there is no specific treatment for NAFLD, one can benefit from losing weight, lowering blood cholesterol/triglycerides/sugar through diet, exercise and sometimes medication. Control it before it is too late, as the liver damage will become irreversible (incurable) if it reaches cirrhosis stage.