PSA Screening Differentiates Cancer from BPH
January 1, 1999
Clinical Briefs
PSA Screening Differentiates Cancer from BPH
By Joan Unger, RN, MS, ARNP-C
Prostate cancer accounts for more than 42% of cancer in males. Serum prostate-specific antigen (PSA) is widely used to detect prostate cancer, but it lacks specificity, especially for 4-10 ng/mL, the range in which just 25% of prostate cancer patients fall. Most patients with PSAs of 4.0 ng/mL and < 10 ng/mL have early-stage cancer. More than 50% with PSAs of > 10 ng/mL have advanced cancer. Measurement of free PSA in serum also helps discriminate between prostate cancer and benign prostatic hypertrophy (BPH). The percentage of free PSA is lower in serum from patients with prostate cancer than in patients with BPH or a normal prostate.
This study of 773 men (379 with prostate cancer, 394 with BPH) ages 50-75 was designed to develop risk assessment guidelines and establish a cutoff value for defining abnormal percentage of free PSA. All subjects had a PSA level 4-10 ng/mL.1 Free PSA percentage may be used as a single cutoff (biopsy all patients at or below 25% free PSA) or as part of patient risk assessment (biopsy based on the individual patient’s risk of cancer).
Using 25% free PSA as a cutoff detected 95% of cancers and avoided 20% of unneeded biopsies. Cancers found with > 25% free PSA were more common in older patients and less threatening in tumor grade and volume. A lower percentage of free PSA was associated with higher risk of cancer (range 8-56%). The free PSA percentage was a more accurate predictor of prostate cancer than age or total PSA.
Reference
1. Catalona W, Partin A, Slawin, K et al. Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease. JAMA 1998;279:1542-1547.
Treating Cardiovascular Risk Factors in Diabetics
The diagnosis of type 2 noninsulin-dependent diabetes markedly increases the risk of coronary heart disease. Clinically established coronary heart disease (CHD) alone increases mortality three to seven times. Plasma cholesterol levels strongly predict risk of cardiovascular events in patients with diabetes and those with CHD. Recommendations for reducing plasma lipids are greater for CHD patients than for diabetics. Some members of the National Cholesterol Education Program panel suggest that diabetics should receive the same intensity of lipid-lowering therapy as CHD patients.
This study compared the seven-year incidence of fatal and nonfatal myocardial infarction among 1373 nondiabetic and 1059 diabetic subjects.1 At baseline, the seven-year incidence rates for MI in nondiabetic subjects with and without prior MI were 18.8% and 3.5%, respectively. Seven-year incidence rates for MI in diabetic patients with and without prior MI were 45% and 20.2%, respectively.
After adjusting for age and sex, the risk of death from CHD for diabetics with no prior MI compared with nondiabetics with previous MI was insignificant (1.4 ± 0.7-2.6), suggesting the MI risk was similar in the two groups. After adjustments for hypertension, smoking, and total cholesterol levels, the risk ratio remained close to 1.0. These data support recommendations for treating diabetic patients with cardiovascular risk factors as aggressively as nondiabetic patients with prior MI. —JU
Reference
1. Haffner S, Lehto S, Ronnemaa R, et al. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. NEJM 1998;339:229-234.
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