View source for Prostate-specific antigen

'''Prostate specific antigen''', abbreviated '''PSA''', is marker that is quite [[specificity|specific]] for the prostate.

==General==
*Quantity in the serum used to screen for [[prostate cancer]].
*PSA [[immunostain]] useful for classifying a carcinoma as prostate carcinoma.

===Serum PSA===
*Normal - typically <= 4.0 ng/mL.
**[[Sensitivity]]: 82% (whites), 90% (blacks).<ref name=pmid8998182>{{Cite journal  | last1 = Henderson | first1 = RJ. | last2 = Eastham | first2 = JA. | last3 = Culkin | first3 = DJ. | last4 = Kattan | first4 = MW. | last5 = Whatley | first5 = T. | last6 = Mata | first6 = J. | last7 = Venable | first7 = D. | last8 = Sartor | first8 = O. | title = Prostate-specific antigen (PSA) and PSA density: racial differences in men without prostate cancer. | journal = J Natl Cancer Inst | volume = 89 | issue = 2 | pages = 134-8 | month = Jan | year = 1997 | doi =  | PMID = 8998182 }}
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**[[Specificity]]: 52% (whites), 38% (blacks).<ref name=pmid8998182/>
*Increases with age.<ref name=pmid12350489>{{cite journal |author=Ku JH, Ahn JO, Lee CH, ''et al.'' |title=Distribution of serum prostate-specific antigen in healthy Korean men: influence of ethnicity |journal=Urology |volume=60 |issue=3 |pages=475–9 |year=2002 |month=September |pmid=12350489 |doi= |url=}}</ref>

===Prostate specific antigen density===
:Abbreviated ''PSAD''.

Normal is often considered to be: <0.15 ng/ml.
*Approximately 8% of individuals below the cut-point (0.15 ng/ml) have medium or high-grade cancer.<ref name=pmid12973074>{{Cite journal  | last1 = Boulos | first1 = MT. | last2 = Rifkin | first2 = MD. | last3 = Ross | first3 = J. | title = Should prostate-specific antigen or prostate-specific antigen density be used as the determining factor when deciding which prostates should undergo biopsy during prostate ultrasound. | journal = Ultrasound Q | volume = 17 | issue = 3 | pages = 177-80 | month = Sep | year = 2001 | doi =  | PMID = 12973074 }}
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*In another series, 48% of individuals with cancer had a PSAD >0.15 ng/ml.<ref name=pmid22482342>{{Cite journal  | last1 = Aganovic | first1 = D. | last2 = Prcic | first2 = A. | last3 = Kulovac | first3 = B. | last4 = Hadziosmanovic | first4 = O. | title = Influence of the prostate volume, prostate specific antigen density and number of biopsy samples on prostate cancer detection. | journal = Med Arh | volume = 66 | issue = 1 | pages = 41-4 | month =  | year = 2012 | doi =  | PMID = 22482342 }}
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*Difference between races have been noted; in those without prostate cancer:<ref name=pmid8998182/>
**0.19 +/- 0.03 ng/ml (blacks).
**0.11 +/- 0.01 ng/ml (whites). 

Better predictor than (unadjusted) serum PSA for:
*Gleason score upgrading on [[prostatectomy]].<ref>{{cite journal |author=Sfoungaristos S, Katafigiotis I, Perimenis P |title=The role of PSA density to predict a pathological tumour upgrade between needle biopsy and radical prostatectomy for low risk clinical prostate cancer in the modified Gleason system era |journal=Can Urol Assoc J |volume=7 |issue=11-12 |pages=E722–7 |year=2013 |pmid=24282465 |pmc=3840515 |doi=10.5489/cuaj.374 |url=}}</ref>
*Benign prostate gland versus [[prostate cancer]].<ref name=pmid1371554>{{cite journal |author=Benson MC, Whang IS, Pantuck A, ''et al.'' |title=Prostate specific antigen density: a means of distinguishing benign prostatic hypertrophy and prostate cancer |journal=J. Urol. |volume=147 |issue=3 Pt 2 |pages=815–6 |year=1992 |month=March |pmid=1371554 |doi= |url=}}</ref><ref>{{cite journal |author=Verma A, St Onge J, Dhillon K, Chorneyko A |title=PSA density improves prediction of prostate cancer |journal=Can J Urol |volume=21 |issue=3 |pages=7312–21 |year=2014 |month=June |pmid=24978363 |doi= |url=}}</ref>

====A forumla for PSAD====
Benson ''et al.'':<ref name=pmid1371554>{{cite journal |author=Benson MC, Whang IS, Pantuck A, ''et al.'' |title=Prostate specific antigen density: a means of distinguishing benign prostatic hypertrophy and prostate cancer |journal=J. Urol. |volume=147 |issue=3 Pt 2 |pages=815–6 |year=1992 |month=March |pmid=1371554 |doi= |url=}}</ref>
:<math>PASD = \frac{serum PSA}{volume}</math>

Where:
:<math>volume = \frac{\pi}{6} H \times W \times L</math>.<ref>{{Cite journal  | last1 = Eri | first1 = LM. | last2 = Thomassen | first2 = H. | last3 = Brennhovd | first3 = B. | last4 = Håheim | first4 = LL. | title = Accuracy and repeatability of prostate volume measurements by transrectal ultrasound. | journal = Prostate Cancer Prostatic Dis | volume = 5 | issue = 4 | pages = 273-8 | month =  | year = 2002 | doi = 10.1038/sj.pcan.4500568 | PMID = 12627211 }}
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:H, W, L are the height, width and length.

An alternate estimation of the volume is:
:<math>volume = \frac{1}{2} D1 \times D2 \times D3</math>.
:D1, D2, D3 are the major axes.

Note:
*The volume of an ellipsoid is:
::<math>\frac{4}{3}\pi D1 \times D1 \times D3</math>.

==See also==
*[[Prostate cancer]].

==References==
{{Reflist|1}}

[[Category:Clinical]]
[[Category:Genitourinary pathology]]