3-4b CLINICAL GUIDELINES: PART II
EARLY DETECTION OF PROSTATE CANCER:
Estimating the risks, benefits and costs
The debate illustrates a clash of perspectives. Should we encourage widespread screening until we prove that it does not work, or should we avoid it until we prove that it does work?
"We believe that the lack of proof of net benefit from early detection with digital rectal examination and PSA measurement and the potential for serious attendant harm mandate a higher level of informed consent than exists for most simple diagnostic tests." "Screening should not be recommended for men who are unwilling to consider aggressive treatment if a tumor of potential clinical significance is found, or who are not candidates for such therapy."
"Available evidence does not justify the common but arbitrary policy of annual digital rectal examination and PSA measurement for men who are older than 50 years of age." Annals Int. Med. March 15, 1997; 126: 468-79

3-4c CLINICAL GUIDELINE: PART III
SCREENING FOR PROSTATE CANCER
In exchange for potential, but unproven benefits, prospective candidates for screening face a 1 to 40% chance (depending on age) of requiring a biopsy. Men who have a radical prostatectomy face greater than a 50% chance of permanent sexual dysfunction, a 20% to 30% likelihood of some degree of urinary incontinence, and up to a 1% chance of perioperative death.
Rather than screening all men for prostate cancer as a matter of routine, physicians should describe the potential benefits and known harms of screening, diagnosis, and treatment, listen to the patients concerns, and then individualize the decision to screen.
Patients who elect to be either by DRE or PSA should provide verbal informed consent. Annals Int. Med. March 15, 1997; 126: 480-84

CLINICAL GUIDELINE: PART I
3-4a EARLY DETECTION OF PROSTATE CANCER
Prior probability and effectiveness of tests.
Prostate cancer (PC) is so common among older men that selecting subpopulations for screening on the basis of risk factors would not be necessary if screening and treatment strategies favorably affecting outcome were available.
The combined use of digital rectal examination (DRE) and currently available assays for prostate specific antigen (PSA) results in as many as 1 of men in their 50s and 40% of men in their 70s requiring further invasive evaluation with biopsy. Positive predictive values are 1 to 21% depending on age.1 Suspicious results on a DRE modestly increase the odds of intracapsular tumors and considerably increase the odds of extracapsular tumors. But if the results of the DRE are not suspicious, the patients pretest odds for PC are not affected and little reassurance is provided about the absence of PC. (Ie, DRE is an inadequate test to rule out PC.)
Men who have lower urinary tract symptoms that are consistent with benign prostatic hyperplasia (BPH) are not more likely to harbor PC. However, the false positive rate of the PSA is increased in men with BPH. (Ie, many more false positive PSA tests.)
Annals Int. Med. March 1, 1997; 126: 394-406 Position Paper, first author from The Massachusetts General Hospital and Harvard Medical School, Boston
1. Positive predictive value = true positive tests / true positive tests + false positive tests. If there is a high rate of false positive tests [low specificity of the test] the positive predictive value will be low.)

CLINICAL GUIDELINES: PART II
3-4b EARLY DETECTION OF PROSTATE CANCER:
Estimating the risks, benefits and costs
Without randomized trials to quantify the risks and benefits of screening for prostate cancer or proof that treating clinically localized cancer reduces disease-specific mortality rates, the available observational data do not warrant the conclusion that early detection of PC using the tests now available unequivocally does more good than harm.
However, the ACP analysis of screening suggests (based on favorable assumptions) that early detection might be cost effective in men in their 50s and 60s. Early detection cannot be dismissed out of hand as definitely ineffective or cost-inefficient in this age group. But, even with the most favorable assumptions, early detection efforts for men over age 70 are only marginally beneficial.
The debate illustrates a clash of perspectives. Should we encourage widespread screening until we prove that it does not work, or should we avoid it until we prove that it does work?
For some patients, the relatively well-defined harms of screening and treatment will appear to overwhelm even the possible maximum benefits. This is so especially since risks are faced immediately whereas potential benefits are usually delayed for years. Others will discount the counterproductive aspects of such complications and accept the associated hazards, even for a benefit of uncertain magnitude.
"We believe that the lack of proof of net benefit from early detection with digital rectal examination and PSA measurement and the potential for serious attendant harm mandate a higher level of informed consent than exists for most simple diagnostic tests." "Screening should not be recommended for men who are unwilling to consider aggressive treatment if a tumor of potential clinical significance is found, or who are not candidates for such therapy."
"Available evidence does not justify the common but arbitrary policy of annual digital rectal examination and PSA measurement for men who are older than 50 years of age."
Annals Int. Med. March 15, 1997; 126: 468-79 Position paper, first author from Massachusetts General Hospital, Boston

Comment:
Is there another reason the diagnose PC other than to lead to surgery and possible cure? Would early detection allow palliative treatment to begin earlier and lead to improvement and lengthening of quality life? RTJ

CLINICAL GUIDELINE: PART III
3-4c SCREENING FOR PROSTATE CANCER
Screening involves testing persons who are asymptomatic of the condition in question. About 1/3 of men who are older than 50 have lower urinary tract symptoms consistent with benign prostatic hyperplasia (BPH). Is testing for PC among such men screening or diagnosis? Recent studies strongly suggest that men who have symptoms consistent with BPH are not at greater risk for PC, aside from the risk conferred by age.

Digital Rectal Examination:
In relatively unselected populations, 7% to 1 of men older than 50 have suspicious results on DRE if the criteria include induration and marked asymmetry in addition to frank nodularity. Data from community-based studies suggests that the positive predictive value of DRE for PC is 1 to 30% (85% to 70% false positives).

PSA:
Because many older men develop BPH, which often elevates PSA levels, the specificity of PSA measurements decreases with age. (More false positives.)
The average cost of PSA measurement is $30 to $40. Because of the substantial cost related to evaluation that can follow abnormal results, the total cost per patient for a combined DRE and PSA is estimated to range from $150 to over $400, depending on the age of the patient.
The likelihood of PC depends on the degree of elevation of the PSA level. For levels between 4 and 10 ng/mL the positive predictive value is about 20%; for levels above 10 ng/ml the positive predictive value increases to between 40% and 60%. Most cases of PC in men who have levels greater than 10 ng/ml are extracapsular and much less likely to be curable.

Potential risks and benefits of screening:
If PSA and DRE are used aggressively, the pathologic stages at which PC will be treated will apparently be earlier compared with historic control cases. However, evidence of stage shift alone is insufficient proof that early detection reduces disease-specific mortality rates.
In exchange for potential, but unproven benefits, prospective candidates for screening face a 1 to 40% chance (depending on age) of requiring a biopsy. Men who have a radical prostatectomy face greater than a 50% chance of permanent sexual dysfunction, a 20% to 30% likelihood of some degree of urinary incontinence, and up to a 1% chance of perioperative death.
Radiotherapy generally poses lower associated risks, but confers a 10% chance of bowel dysfunction.
Using a favorable set of assumptions, PSA and DRE screening may eventually prove to have a clinically important net benefit and a reasonable cost for men of average health who are in their 50s and 60s. With assumptions that are less favorable, the net benefit will decrease and costs increase. Because of the uncertainty about which combination of assumptions is valid, this analysis cannot be used to effectively argue for or against screening.

Recommendation:
Rather than screening all men for prostate cancer as a matter of routine, physicians should describe the potential benefits and known harms of screening, diagnosis, and treatment, listen to the patients concerns, and then individualize the decision to screen.
Patients who elect to be either by DRE or PSA should provide verbal informed consent.
Annals Int. Med. March 15, 1997; 126: 480-84 Guideline from the ACP

Comment:
Asking for informed consent for a screening DRE would present practical difficulties. Rectal exams are performed routinely for a number of reasons including in conjunction with a flexible sigmoidoscopy. Is the clinician to avoid feeling the prostate? Unlikely. If an abnormality is suspected is the clinician then to request informed consent to repeat the DRE, this time for screening for PC? RTJ

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