With the advent of the PSA (Prostate Specific Antigen) blood test two decades ago, the screening for and detecting of prostate cancer in the United States has been revolutionized.

Introduction

PSA is a protein manufactured in the prostate. There is an association between the PSA level and the likelihood of the man having prostate cancer.

Previously, the only screening test for prostate cancer was a digital rectal exam. That meant a physician inserted his or her gloved finger into the mans rectum to determine if he or she felt any lumps or bumps in the prostate gland. By that point, the cancer was relatively far advanced. Fortunately, PSA blood tests can detect a prostate malignancy at a much earlier stage. This is known as a stage shift.

When is a PSA level elevation significant?

As men age, they often develop a non-cancerous increase in the size of the prostate, known as benign prostatic hyperplasia. This also elevates PSA, which leads to controversy as to whether or not to send the man for a prostate biopsy. The latter is an invasive procedure, but it is the method by which prostate cancer is diagnosed.

Over the last twenty years, much research took place to determine what constitutes a normal PSA level. In the '80s and '90s, physicians used a cutoff of a value of 4. However, doctors now know that there is really no "normal" level of PSA. Instead, there are ranges and trends of PSA. Generally, the current acceptable cutoff is 2.5, so any level above 2.5 is considered an abnormal PSA.

The normal level of PSA changes over a man's lifetime. As previously stated, as a man ages, the prostate glands volume increases. Thus, the actual cut off point of normal PSA level changes as a function of age.

For men in their 70s, one might accept a level of 2.5 because the likelihood of that person's elevation of PSA being a consequence of benign prostatic hyperplasia is much greater than his likelihood of having prostate cancer. For younger men, it might be worrisome when the PSA rises to 2.5.

PSA level trends

Physicians are also interested in how the PSA level changes over time. For example, a PSA that rose gradually over many years, even if the level itself were over 4, is much less concerning than a number that jumped from 2 to 4 in one year. The rate change of PSA over time is known as the PSA velocity. Also, PSA doubling time is the time it takes for the PSA to go from some level to twice that level.

In a man with prostate cancer, the shorter the PSA doubling time is, the greater the rate of growth of the disease. This is a prognosticator and it suggests the need for medical intervention instead of observation.

PSA level to monitor the activity of prostate cancer

Treatment for early stage prostate cancer is usually local therapy, namely surgery or radiation therapy. When the prostate is removed, PSA levels normally drop to zero. When radiation is used, there may still be some detectable PSA, but at very low levels.

After surgery or radiation, physicians generally check the PSA every three months for a few years. When the PSA level remains stable over time, the likelihood is strong that the person has been cured. Thereafter, doctors can decrease the interval of checking the PSA.

Ongoing measurements of PSA are an important means to follow a person with a history of prostate cancer. While there is controversy about using PSA as a screening tool in the general population, there is none about the value of PSA as a monitoring tool in someone who has been treated for prostate cancer.

When the PSA level climbs over several sequential measurements, it is considered to represent what is called a biochemical failure, PSA-detectable disease, or PSA recurrence. How to manage a PSA recurrence varies from one patient to the next. Certainly, there are men who have a rising PSA after local therapy who will never have any problem with recurrent cancer.

However, there are people who will develop a cancer recurrence, characterized by a rapidly rising PSA before they have detectable cancer on a scan. Aggressive treatments can make a difference in the lives of these men.

Treatment for PSA recurrence

Currently available treatments include the use of hormonal or androgen-deprivation therapy, to prevent the production or action of the male hormone testosterone on prostate cancer cells. This can be achieved via the surgical removal of the testicles, or, more commonly, through the use of hormonal medications.

Unfortunately, hormonal treatments often fail after a period of time, and rising PSA levels may be the first indication. If the PSA is rising, it signifies what is called hormone-refractory prostate cancer. Nonetheless, in this late stage of disease, further treatment is still available.

Over the past year or two, more studies have proven the benefit of chemotherapy in advanced prostate cancer. Not only does chemotherapy prolong life in men with hormone-refractory prostate cancer, but it can also improve their quality of life.

Conclusions

While debate remains about the best use of PSA testing in the population at large, especially for screening, experts agree that PSA and its relationship to prostate cancer has had a significant effect on making treatment decisions for a disease that affects a many men.

Copyright 2006 by Carol Kornmehl. All rights reserved. No part of this article may be copied without express written permission by the author.