Prostate Cancer Project Flashcards
How common is this condition?
- Risk of diagnosis/death in screened population.
- eg. over 10 yrs or lifetime? (percentage)
It has been estimated that 15%-30% of men over 50, and about 80% of men over 80 harbor microscopic, undiagnosed prostate cancer in the United States.
PCa is diagnosed in 1 of 6 U.S. men; however it is only fatal in 3% of men.
Approximately 11.2 percent of men will be diagnosed with prostate cancer at some point during their lifetime
Who is most at risk of this condition (and thus most likely to benefit from screening)?
Variations in the clinical incidence of Pca are present, including an alarmingly high rate of African American incidence versus other non-western cultures.
Higher death rates, it has been observed that the onset of PCa occurs at an earlier age in African Americans in the United States.
Briefly describe the commonly accepted screening modality or modalities.
Prostate-specific antigen (PSA) is a glycoprotein produced by prostate epithelial cells.
PSA elevations can precede clinical disease by 5 to 10 years or even longer.
However, PSA is also elevated in a number of benign conditions particularly benign prostatic hyperplasia (BPH) and prostatitis.
DIGITAL RECTAL EXAMINATION (DRE) can detect palpable abnormalities (eg, nodules, asymmetry, or induration) in the posterior and lateral aspects of the prostate gland where the majority of cancers arise; however, other areas of the prostate where cancer occurs are not reachable by a finger examination.
How often is the test correct?
- (sensitivity and specificity may vary depending on the study, diagnostic threshold, and gold standard comparison).
- Please report likelihood ratios for negative and positive tests.
The estimated sensitivity of a PSA cutoff of 4.0 ng/mL was 21 percent for detecting any prostate cancer and 51 percent for detecting high-grade cancers.
The estimated specificity was 91 percent for a PSA cutoff of 4.0 ng/mL.
The positive predictive value for a PSA level >4.0 ng/mL is approximately 30 percent
Likelihood ratio for PSA >4 ng/mL 3.39
The 4 ng/ml cutpoint was associated with a likelihood ratio for a positive test of 1.28 and 0.42 for a negative test.
What are the potential benefits of screening?
- Please report estimated risk of mortality (or morbidity if mortality not applicable) WITHOUT the screening test and then WITH the screening test.
- The difference is the absolute risk reduction.
- Report the number needed to screen to prevent an outcome. This is typically reported over 5-10 yrs.
- Report on relative risk reduction and comment on how does this differ from the absolute risk reduction? If no RCT applicable then do not need to report NNT.
Roughly a 25 to 30 percent (95% CI range 10-47) relative risk reduction in prostate cancer mortality in the PCLO and ERSPC trials.
With follow-up truncated at 13 years, the primary outcome of prostate cancer mortality was 20 percent lower in the group offered screening.
The absolute rates of prostate cancer mortality were 0.43 versus 0.54 per 1000 person-years (absolute rate difference of 0.11 fewer deaths per 1000 person-years
781 (95% CI 490-1929) men needed to be invited for screening to prevent one prostate cancer death over 13 years [Number needed to screen].
Prostate cancer was diagnosed more frequently in the screening group (9.6 versus 6.2 cases per 1000 person-years), such that 27 additional cases of prostate cancer would need to be detected by screening to prevent one death from prostate cancer after 13 years.
All-cause mortality in the core group was not reduced with screening (18.6 versus 18.9 deaths per 1000 person-years; rate ratio 1.00, CI 0.98-1.02). Prostate cancer mortality was also reduced in the entire cohort of men ages 50 to 74 (RR 0.83, CI 0.73-0.94).
- *What are the potential harms of screening?**
- How common are false positives?
- How common is overdiagnosis (if available)?
- Why might these be problematic?
Screening may lead to:
Aggressive treatments: (unecessary biopsies, radiation therapy, radical prostatectomy) all which can lead to:
Urinary incontinence or erectyle dysfunction.
Harms of screening included false‐positive results for the PSA test and overdiagnosis (up to 50% in the ERSPC study)
What are current USPSTF recommendations?
Grade C: For men aged 55 to 69 years, the decision to undergo periodic prostate-specific antigen (PSA)–based screening for prostate cancer should be an individual one.
Screening offers a small potential benefit of reducing the chance of death from prostate cancer in some men. However, many men will experience potential harms of screening, including false-positive results that require additional testing and possible prostate biopsy; overdiagnosis and overtreatment; and treatment complications, such as incontinence and erectile dysfunction. In determining whether this service is appropriate in individual cases, patients and clinicians should consider the balance of benefits and harms on the basis of family history, race/ethnicity, comorbid medical conditions, patient values about the benefits and harms of screening and treatment-specific outcomes, and other health needs. Clinicians should not screen men who do not express a preference for screening.
Grade D: The USPSTF recommends against PSA-based screening for prostate cancer in men 70 years and older.
Consider the benefits and risks of screening and indicate whether you would recommend for your patients.
Risks incurred by screening, diagnosis, and resulting treatment of prostate cancer are both substantial and well documented in the literature. To the extent that overdiagnosis occurs with prostate-cancer screening, many of these risks occur in men in whom prostate cancer would not have been detected in their lifetime had it not been for screening. The effect of screening on quality of life is a subject of an ongoing substudy and should be completed within the next several years.
