|
 The American Cancer Society (ACS) recommends that physicians offer both the PSA blood test and digital rectal examination (DRE) annually, beginning at age 50, to men who have at least a 10-year life expectancy.
In addition, ACS recommends that men at high risk begin testing at age 45. High risk categories include:
- Ethnicity. African-American men are more likely to get prostate cancer and twice as likely to die of prostate cancer than Caucasian men in the United States. Environmental causes are suspected because prostate cancer occurs at much lower rates in Africa than in the United States.
- Family history. If a man has a father or brother who got prostate cancer before the age of 65, he is more likely to get the disease.
- Diet. It appears that a diet that is high in red meat and/or high-fat dairy products and low in fruits and vegetables increases the risk for prostate cancer.
ACS further suggests that men at very high risk — for example, men with multiple close family members who got the disease before age 65 — start screening at age 40. If the results of the initial screening warrant it, further screening might be put off until age 45.
In current clinical practice, prostate biopsy is recommended for men with a suspicious DRE result, regardless of the total PSA level. Patients with PSA greater than 10 ng/mL should also undergo biopsy since the rate of cancer is high in this group (>50%). Although biopsy usually is recommended for men with nonsuspicious DRE results and PSA between 4 and 10 ng/mL, only 25% of these men have cancer.
Specificity can be improved in this population since 75% of the biopsies are negative, however. It is common to recommend a free PSA test — for example, Beckman Coulter’s Hybritech free PSA test — as a follow-up procedure in these circumstances. By determining the percent of free PSA to total PSA, physicians can detect 95 percent of cancers and reduce unnecessary prostate biopsies by 20 percent, according to a multi-center study headed by William Catalona, M.D. (Catalona WJ, et al. Use of the percentage of free prostate specific antigen to enhance differentiation of prostate cancer from benign prostatic disease: A prospective multicenter clinical trial. JAMA 279:1542-1547, 1998.)
 |
The Hybritech® free PSA test helps determine the percent of free PSA. And the measurement of percent free PSA improves the accuracy of prostate cancer detection while eliminating a projected 20 percent of all prostate biopsies. The free PSA test is used following a non-suspicious DRE and a total PSA test that shows moderately elevated PSA levels (between 4 and 10 ng/mL) in men aged 50 years and older. |
It is important to note that for accurate measurement of free PSA, the PSA and free PSA tests should be by the same manufacturer. PSA tests are not all standardized, so PSA and free PSA results must be calibrated to each other to have validity. This is easily accomplished with Hybritech tests.
An increase in PSA results of 20 percent to 30 percent in a single year may be cause for concern about possible prostate cancer, even if the overall PSA is relatively low. (Eastham, JA, et al, JAMA 2003;289:2695). Because PSA tests are not all standardized, it is important to get each year’s PSA test performed at the same lab using the same test by the same manufacturer. (NACB Practice Guidelines and Recommendations for Use of Tumor Markers in the Clinic (2005 draft). Section3B, Use of Tumor Markers in Prostate Cancer, H. Lilja, et.al).
|
