CLINICAL UPDATE
PSA screening , in context
PSA has become an acronym that provokes strong responses . Essentially , men who are not suitable for consideration of curative intent treatment should not be screened . Men whose screening is positive need appropriate referral so the patient is not faced with a situation where delay has culminated in incurable disease . This may have profound medicolegal consequences for the referring Doctor .
PSA ’ s strengths and weaknesses
PSA screening needs to be considered in context , like any other test . With regard to prostate cancer it has a sensitivity (~ 21 % for detecting any cancer at a PSA cut-off of 4ng / mL ), a specificity (~ 91 % for a PSA cut-off of 4.0 ng / mL ), a positive predictive value (~ 30 % for a PSA > 4ng / mL ) and a negative predictive value (~ 85 % for a PSA ≤4 ng / mL ).
While prostate cancer can be diagnosed at any level of PSA , concluding that “ PSA testing can ’ t detect prostate cancer ” ( as the discoverer of PSA Richard Ablin stated in an oft quoted 2010 op-ed in the New York Times ) is to throw the baby out with the bath-water .
Despite its limitations , it remains overwhelmingly the best prostate cancer tumour marker that we have .
US & Australian recommendations
PSA screening for cancer is contentious . The American Urological Association ( AUA ) has just issued revised guidelines that should be considered alongside the Urological Society of Australia and New Zealand ( USANZ ) recommendations :
�� �������������������������������
�� ���������������������������������������� screening between ages 40-54 only in those at higher risk ( e . g . positive family history or African-American race ), and according to patient-doctor wishes .
�� ������������������������������������ significant predictor of later prostate cancer and disease-specific outcomes . USANZ recommend men interested in their prostate health have a single PSA test and digital rectal examination ( DRE ) at or beyond age 40 , to help estimate prostate cancer risk over the next 10-20 years . In these circumstances PSA is considered as providing prostate cancer risk stratification rather than true screening . If the result is less than the age specific median , the intensity of surveillance may be reduced but those with PSA levels above should be more carefully monitored .
�� ������������������������������������� in men aged 55-69 ; both the AUA and USANZ recommends doctor-patient shared decision-making based on a man ' s values and preferences .
�� ����������������������������������������� years ( or less often ) may be preferred over annual screening , to preserve most benefits reduced by false positives ; rescreening intervals can be individualised according to a baseline PSA level .
Dr Robert Davies , Urologist ,
West Australian
Urologic Research Organisation . Tel 9381 8945
�� ����������������������������������� PSA screening over age 70 or in any man with < 10-15 year life expectancy ( although some over age 70 and in excellent health may benefit ).
In short , PSA screening should be confined to men who are most likely to benefit from early diagnosis and treatment .
Act on screening results
PSAs appropriately performed in a man suitable for curative intent treatment , should be acted on . Whilst repeating an isolated elevated PSA after a few months is a reasonable first course of action , watching serial PSAs gradually progress from minimally to exceedingly elevated over several years is akin to allowing a patient to gradually exsanguinate whilst dutifully measuring a rising pulse and falling blood pressure .
Since the risk of extra prostatic spread increases continuously as PSA rises , early referral can mean the difference between detection of localised ( curable ) versus locally advanced or metastatic ( incurable ) disease . The proportion of organ-confined cancers drops to < 50 % for PSA values > 10ng / mL .
��Performing high dose rate prostatic brachytherapy at SCGH .
Rectal examination
PSA has not replaced digital rectal examination ( DRE ) – both should be performed as part of screening , as in combination , the positive predictive value doubles when the PSA is in the 4-10ng / mL range . Furthermore , the risk of missing a significant high grade cancer by omitting the DRE has been estimated at 17 % in one major study .
Author competing interests : No relevant disclosures .
Medicolegal
Stray Tests
Q “ Three
patients have recently asked me to order tests for them , after non-medicos requested this . One wanted an antenatal screen and had no intention of attending any medico or midwife for pregnancy care . One suggested we do a PSA , which I
Ms Morag Smith , Avant ’ s Senior Solicitor , answers the question for Medical Forum .
disagreed with . The other wanted a re-test of her thyroid , which her naturopath said was warranted and cheaper under Medicare . Where do I stand , in a medicolegal sense ?”
APatients who insist on seeing a non-medical person for follow up and treatment should be informed of the risks of obtaining treatment from someone who is not a doctor . The discussion should involve taking steps to ascertain the patient ’ s understanding of their condition and reasons for , and the nature of , treatment . If , despite counselling , the patient continues to refuse to see you for follow up , you may want to consider whether to end the doctor-patient relationship due to the patient ’ s failure to follow your advice and recommendations . Details of the discussion should be documented in the patient ’ s file . You should only agree to a test or investigation requested by a non-medical third party if you believe it is clinically indicated . Should you agree to conduct a test or investigation , you still need to take a history and examine the patient to confirm that the test is clinically indicated . In addition , you still owe a duty to the patient to inform them of any finding that requires follow up . This duty applies even if the patient states they do not intend returning to see you to discuss the results . If a patient requests a test or investigation and you do not agree that the test / investigation is required , it is not advisable to comply with the patient ’ s request . Medicare pays for clinically-relevant services . This means services that are generally accepted by your peers as being necessary for the appropriate treatment of the patient . If you order a test that is not clinically relevant , you risk a possible review by the Department of Human Services . It is also possible that you could face disciplinary proceedings .
Finally , you can always contact your MDO for advice on managing situations such as this . �
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