Labtech

PSA—Screening Test for Prostate Cancer

A man is 35 per cent more likely to be diagnosed with prostate cancer than a woman is to be diagnosed with breast cancer.

Dr Avinash A Phadke

Prostate cancer occurs when the cells of the prostate begin to grow uncontrollably. When caught and treated early, prostate cancer has a cure rate of over 90 per cent. Yet being diagnosed with prostate cancer can be a life-altering experience. It requires making some very difficult decisions about treatments that can affect not only the life of the man diagnosed, but also the lives of his family members in significant ways for many years to come.

In 2007, according to estimates, more than 2,18,000 men will be diagnosed with prostate cancer, and more than 27, 000 men will die from the disease. One new case occurs every 2.5 minutes and a man dies from prostate cancer every 19 minutes. In fact, a man is 35 per cent more likely to be diagnosed with prostate cancer than a woman is to be diagnosed with breast cancer. The older you are, the more likely you are to be diagnosed with prostate cancer.

Risk Factors

Men with a single first-degree relative—father, brother or son—with a history of prostate cancer are twice as likely to develop the disease, while those with two or more relatives are nearly four times as likely to be diagnosed. The risk is even higher if the effected family members where diagnosed at a young age, with the highest risk seen in men whose family members were diagnosed before the age of 60.

Symptoms of Prostate Cancer

Early diagnosis of carcinoma of prostate is hindered by lack of symptoms in men with localised tumours. Some men, however, will experience symptoms such as frequent, hesitant, or burning urination, difficulty in having an erection, or pain or stiffness in the back, hips or upper thighs.

Prostate-specific Antigen

Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland into seminal fluid. The PSA test measures the level of PSA in the blood. PSA is simple, safe and non-invasive test for early detection. It is normal for men to have low levels of PSA in their blood; however, prostate cancer or benign conditions can increase PSA levels. As men age, both benign prostate conditions and prostate cancer become more frequent. The most common benign prostate conditions are prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BHP) (enlargement of the prostate).

PSA levels alone do not give doctors enough information to distinguish between benign prostate conditions and cancer. However, the doctor will take the result of the PSA test into account when deciding whether to check further for signs of prostate cancer.

American Urological Association endorsed annual examination with Digital Rectal Examination (DRE) and PSA, for early detection of prostate disease, beginning from the age of 50 years. PSA is recommended once in a year after the age of 50 years.

Clinical Significance of PSA Levels

Increase in levels of PSA may suggest the presence of prostate cancer. However, prostate cancer can also be present in the complete absence of an elevated PSA level, in which case the test result would be a false negative. PSA levels can be also elevated due to prostate infection, irritation, benign prostatic hypertrophy (enlargement) or hyperplasia (BPH) or recent ejaculation.

PSA also has a significant value in detecting metastatic or pre-existent disease in patients following surgical or medical treatment of prostate cancer. PSA test is widely accepted as an adjunct in the management of prostate cancer.

PSA is present in blood as free and protein-bound PSA. A small amount of PSA is not protein bound and is called free PSA. Percentage of free PSA is lower in patients having prostate cancer than being disease. In men with prostate cancer ,the ratio of free (unbound) PSA to total PSA is decreased.

The risk of cancer increases if the free to total ratio is less than 25 per cent. The lower the ratio the greater the probability of prostate cancer.

Measuring the ratio of free to total PSA appears to be particularly promising for eliminating unnecessary biopsies in men with PSA levels between 4 and 10 ng/ml.

When Should One Be Screened?

The American Cancer Society recommends that both the PSA and DRE should be offered annually, beginning at the age of 50, to men who have at least a 10-year life expectancy. Men at high risk, such as African American men and men with a strong family history of one or more first-degree relatives diagnosed at an early age, should begin testing at the age of 45.

E-mail: npilphadkelab@vsnl.net
The author is the Director of Wellspring Path Lab