Among men undergoing prostate biopsy, the probability of having prostate cancer varied by serum level of prostate-specific antigen (PSA), family history of prostate cancer, digital rectal exam result, and results of previous prostate biopsies. These results were published in the Journal of the National Cancer Institute.
The prostate is a gland of the male reproductive system. It produces some of the fluid that transports sperm during ejaculation. After skin cancer, prostate cancer is the most common form of cancer diagnosed in men.
Men 50 years or older in the U.S. are often offered PSA testing for the early detection of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate.
Concerns exist that PSA tests may produce false-positive results (elevated PSA in response to non-cancerous conditions) as well as false-negative results (low PSA when cancer is present). Researchers are therefore interested in identifying more accurate tests for the early detection of prostate cancer.
In order to determine whether other factors in addition to PSA can be used to estimate the risk of having prostate cancer, researchers analyzed information from 5519 men who had participated in a clinical trial. As part of their study participation, all men underwent a prostate biopsy regardless of their PSA level. A total of 1211 men (22%) were diagnosed with prostate cancer.
The CA 125 “tumor associated protein” or “tumor marker”
Answers to frequently asked questions about CA 125.
- Factors that were linked with a higher probability of cancer were higher PSA level, a positive family history of prostate cancer, and an abnormal digital rectal exam result.
- Having a previous negative biopsy was linked with a lower probability of cancer.
- After accounting for other factors, neither age nor PSA velocity (the rate at which PSA was increasing) were linked with the probability of cancer.
- Factors that were linked with a higher probability of having high-grade cancer (Gleason score of 7 or higher) were higher PSA level, abnormal digital rectal exam result, older age at biopsy, and African-American race. Men with a previous negative biopsy had a lower probability of having high-grade cancer.
The researchers suggest that these findings may be used to estimate an individual’s risk of prostate cancer, and to guide decisions about when a prostate biopsy is warranted. An accompanying editorial, however, notes that the current study may have detected a disproportionate number of non-life-threatening cancers, and that applying the risk-estimation tool developed by the study may further contribute to the over-diagnosis of prostate cancer.
Reference: Thompson IM, Ankerst DP, Chi C et al. Assessing Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial. Journal of the National Cancer Institute. 2006;98:529-534.
Accompanying Editorial: Carter HB. Assessing Risk: Does This Patient Have Prostate Cancer? Journal of the National Cancer Institute. 2006;98:506-507.
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