Measurement of prostate-specific antigen in serum as a screening test for prostate cancer

Article Abstract:

The prostate is a walnut-sized gland in men that surrounds the neck of the bladder and the urethra. Cancer of the prostate is the second leading cause of death from cancer among American men, because by the time it is first identified, the cancer has usually spread to other parts of the body. Prostate-specific antigen (PSA) is excreted by the cells lining the prostate. Up to half of patients with benign prostatic hyperplasia (enlarged prostate, a common condition among older men) have elevated levels of PSA. PSA is also elevated in 25 to 92 percent of patients with prostate cancer, depending on tumor volume. PSA is used to measure progression of prostate cancer and response to therapy, but whether it is useful for early detection and evaluation of prostate cancer is not known. Measurement of PSA in the blood is more precise than rectal examination or transrectal ultrasound, and is more acceptable to patients. To determine the usefulness of PSA as a screening tool, 1,653 healthy men were tested, 112 of whom underwent biopsies. In addition, 300 men were evaluated with ultrasonography, and PSA was measured for 235 of them. The predictive value of PSA was better than rectal examination or ultrasonography. Among the 37 men in the study group who had cancer, rectal examinations alone would not have detected 12 tumors, and for five of the men, a high level of PSA was the only suspicious finding. PSA measurement may miss some cases of prostate cancer, and may also indicate cancer when there is none. An enlarged prostate, prostatitis (inflammation of the prostate), biopsy, and rectal examination itself can raise PSA levels, leading to false suspicions of cancer, and the resulting mental and physical distress. Also, one third of men over the age of 50 have latent prostatic cancers which will never cause illness or death, and there is concern that screening will detect these tumors. In addition, treatment of latent prostate cancer may cause more illness and deaths than the disease itself. It is concluded, nevertheless, that PSA is a useful addition to rectal examination in improving the diagnosis of prostate cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Tumor antigens

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Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening

Article Abstract:

Unnecessary prostate biopsies may be reduced by measuring the percentage of free serum prostate-specific antigen (PSA) and bound forms of PSA in serum. PSA measurement is a screening test for prostate cancer. Researchers measured total serum PSA levels in 10,249 healthy men aged 50 and older. A total of 113 men had serum PSA concentrations of 4.1 to 10.0 ng/mL. Men whose serum PSA concentrations were higher than 4.0 ng/mL had prostatic ultrasonography and digital rectal exams. Needle biopsies were performed on the men with abnormal results. A monoclonal antibody immunoassay specific for free PSA and another antibody immunoassay recognizing both free and bound PSA were used to determine if the percentage of free PSA was a predictor of prostate cancer. The median percentage of free PSA was 9.2% in men with cancer and a normal gland, 15.9% in men with cancer and an enlarged gland, and 18.8% in men with benign prostatic hyperplasia. Common causes of elevated PSA are benign prostatic hyperplasia and prostatitis.

Prostate-specific antigen, Prostate specific antigen

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Detection of organ-confined prostate cancer is increased through prostate-specific antigen-based screening

Article Abstract:

Measurement of blood levels of prostate-specific antigens (PSA) may be more effective than a digital rectal examination (DRE) for early diagnosis of prostate cancer. Prostate cancer is one of the most common types of cancer that occurs in men. Among 420 men over 50 years old who were diagnosed with prostate cancer, 244 had initial measurement of their PSA levels, 129 had serial measurements of their PSA levels and 47 had a DRE (control group). Advanced prostate cancer was diagnosed in 37% of the patients in the initial screening group and 29% of the serial screening group, compared with 57% of those in the control group. PSA screening was most beneficial in patients under 70 years old for the early diagnosis of prostate cancer.

Medical examination, Men, Tissue specific antigens

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