Prostate cancer screening

Prostate cancer screening is an attempt to identify individuals with prostate cancer in a broad segment of the population—those for whom there is no reason to suspect prostate cancer. There are currently two methods used: One is the digital rectal examination (DRE), in which the examiner inserts a gloved, lubricated finger into the rectum to examine the adjoining prostate. The other is the prostate-specific antigen (PSA) blood test, which measures the concentration of this molecule in the blood.

The decision to screen has many controversies, such as screening older men for whom benefit is least clear.^[1]

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Interpreting the results of screening tests

Two clinical prediction rules help predict the probability of cancer based on the level of the prostate-specific antigen and other clinical findings.^[2][3]

Randomized controlled trials

Randomized controlled trials have not yet shown that early detection of prostate cancer with PSA testing does more harm than good, but many feel that the 4% annual decline in prostate cancer mortality rate in the United States over the past decade must be attributable to PSA screening, though improvements in treatment, including more widespread use of androgen deprivation for advanced cancer, may explain some of this trend. It is hoped that the results within the next decade of three ongoing very large randomized controlled trials will show whether early detection of prostate cancer with PSA testing does more harm than good:^[4][5]

1. The European Randomized study of Screening for Prostate Cancer (ERSPC) has randomized over 200,000 men aged 55-74 at centers in 8 European countries since 1993 to usual care or prostate cancer screening with PSA and DRE (biopsy if PSA ≥ 3)^[6]
2. The NCI Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial randomized 77,000 men aged 55-74 at centers in 10 U.S. states from 1992-2001 to usual care or prostate cancer screening with PSA and DRE (biopsy if PSA > 4)^[7]
3. The NHS Comparison Arm for ProtecT (CAP) and Prostate testing for cancer and Treatment (ProtecT) studies randomized GP practices with 460,000 men aged 50-69 at centers in 9 cities in Britain from 2001-2005 to usual care or prostate cancer screening with PSA (biopsy if PSA ≥ 3)^[8]

Clinical practice guidelines

Clinical practice guidelines for prostate cancer screening are controversial because the benefits of screening may not outweigh the risks of follow-up diagnostic tests and cancer treatments:

• U.S. Preventive Services Task Force (USPSTF):^[9][10][11]

"the evidence is insufficient to recommend for or against routine screening for prostate cancer using prostate-specific antigen (PSA) testing or digital rectal examination (DRE). This is a grade I recommendation"

• American Cancer Society, in 2001, recommended:^[12][13][14]

"The PSA test and the DRE should be offered annually beginning at age 50 to men who have a life expectancy of at least 10 years. Men at high risk should begin testing at age 45. Information should be provided to patients about benefits and limitations of testing."

The American Cancer Society recommends that individual men discuss the potential benefits and risks of testing with their doctors in order to make an informed decision on whether or not to be tested. Screening should be offered annually to African-American men and those with a family history of prostate cancer upon reaching 45 years. Other racial and ethnic groups, such as Asian- and Hispanic-Americans have a lower risk of prostate cancer, and may not benefit from screening. Screening is likely not useful for men over age 70 or with other significant medical problems and a life expectancy of fewer than 10 years.

References

1. ^ Scales C, Curtis L, Norris R, Schulman K, Albala D, Moul J (2006). "Prostate specific antigen testing in men older than 75 years in the United States.". J Urol 176 (2): 511-4. PMID 16813879.
2. ^ Nam RK, Toi A, Klotz LH, et al (2007). "Assessing individual risk for prostate cancer". J. Clin. Oncol. 25 (24): 3582–8. doi:10.1200/JCO.2007.10.6450. PMID 17704405.
3. ^ Thompson IM, Ankerst DP, Chi C, et al (2006). "Assessing prostate cancer risk: results from the Prostate Cancer Prevention Trial". J. Natl. Cancer Inst. 98 (8): 529–34. doi:10.1093/jnci/djj131. PMID 16622122. Online calculator
4. ^ Ilic D, O'Connor D, Green S, Wilt T (July 19, 2006). "Screening for prostate cancer". Cochrane Database Syst Rev. PMID 16856057.
5. ^ Barry MJ (April 2007). "Review: evidence from 2 low quality screening studies does not show a reduction in death from prostate cancer". Evid Based Med 12 (2): 40. PMID 17400632.
6. ^ ESPRC (October 14, 2007). European Randomized study of Screening for Prostate Cancer. Erasmus MC.
   ISRCTN (October 19, 2007). European Randomized study of Screening for Prostate Cancer. isrctn.org.
7. ^ Division of Cancer Prevention (2007). Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. National Cancer Institute.
8. ^ ProtecT (July 25, 2007). ProtecT Study (Prostate testing for cancer and Treatment). University of Bristol Dept. of Social Medicine.
   ISRCTN (March 6, 2006). The CAP (Comparison Arm for ProtecT) study. isrctn.org.
   ISRCTN (November 19, 2007). The ProtecT trial. isrctn.org.
9. ^ U.S. Preventive Services Task Force (2002). "Screening for prostate cancer: recommendation and rationale". Ann. Intern. Med. 137 (11): 915-6. PMID 12458992.
10. ^ Harris R, Lohr KN (2002). "Screening for prostate cancer: an update of the evidence for the U.S. Preventive Services Task Force". Ann. Intern. Med. 137 (11): 917-29. PMID 12458993.
11. ^ U.S. Preventive Services Task Force (December 2002)). Screening for Prostate Cancer. Retrieved on 2006-09-14.
12. ^ Smith RA, von Eschenbach AC, Wender R, et al (2001). "American Cancer Society guidelines for the early detection of cancer: update of early detection guidelines for prostate, colorectal, and endometrial cancers. Also: update 2001--testing for early lung cancer detection". CA: a cancer journal for clinicians 51 (1): 38-75; quiz 77-80. PMID 11577479.
13. ^ National Guideline Clearinghouse. Recommendations from the American Cancer Society Workshop on Early Prostate Cancer Detection. Retrieved on 2006-09-14.
14. ^ American Cancer Society. What the American Cancer Society Recommends. Retrieved on 2007-01-16.