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Prostate-specific antigen (view source)
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'''Prostate specific antigen''', abbreviated '''PSA''', is marker that is quite [[specificity|specific]] for the prostate. | [[Image:Advanced prostate carcinoma - PSA - 2 -- very high mag.jpg|thumb|200px|[[Micrograph]] showing a PSA immunostain marking [[prostate carcinoma]].]] | ||
'''Prostate-specific antigen''', abbreviated '''PSA''', is marker that is quite [[specificity|specific]] for the prostate. | |||
==General== | ==General== | ||
*Quantity in the serum used to screen for [[prostate cancer]]. | *Quantity in the serum used to screen for [[prostate cancer]] and follow patients with a history of prostate cancer. | ||
*PSA [[immunostain]] useful for classifying a carcinoma as prostate carcinoma. | *PSA [[immunostain]] useful for classifying a carcinoma as prostate carcinoma. | ||
===Serum PSA=== | ===Serum PSA=== | ||
*Normal - typically < 4.0 ng/ | *Normal - typically <= 4.0 ng/ml. | ||
*Increases with age.<ref>{{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> | **[[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 }} | ||
</ref> | |||
**[[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> | |||
Age-normal: | |||
* | *40s - 2.5 ng/ml. | ||
*50s - 3.5 ng/ml. | |||
*60s - 4.5 ng/ml. | |||
*70s - 6.5 ng/ml. | |||
Note: | |||
*The units for PSA may also be μg/L; note that 1 μg/L = 1 ng/ml. | |||
====Prostate-specific antigen density==== | |||
:Abbreviated ''PSAD''. | |||
Normal is often considered to be: <0.15 ng/ml<sup>2</sup>. | |||
*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 }} | |||
</ref> | |||
*In another series, 48% of individuals with cancer had a PSAD >0.15 ng/ml<sup>2</sup>.<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 }} | |||
</ref> | |||
*Differences between races have been noted in one study; in those without prostate cancer:<ref name=pmid8998182/> | |||
**0.19 +/- 0.03 ng/ml<sup>2</sup> (blacks). | |||
**0.11 +/- 0.01 ng/ml<sup>2</sup> (whites). | |||
PSAD is a 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> | *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> | *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==== | =====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> | 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> | :<math>PASD = \frac{serum PSA}{volume}</math> | ||
Where: | 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 }} | |||
</ref> | |||
: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>. | :<math>volume = \frac{1}{2} D1 \times D2 \times D3</math>. | ||
:D1, D2, D3 are the major axes. | :D1, D2, D3 are the major axes. | ||
Notes: | |||
*The volume of an ellipsoid is: | *The volume of an ellipsoid is: | ||
::<math>\frac{4}{3}\pi D1 \times D1 \times D3</math>. | ::<math>\frac{4}{3}\pi D1 \times D1 \times D3</math>. | ||
*As 1 cm<sup>3</sup> is equal to 1 ml, the units of PSAD are (ng/ml)/cm<sup>3</sup> or ng/ml<sup>2</sup>. | |||
====Free serum PSA/total PSA==== | |||
:Also ''PSA free-to-total ratio'' (abbreviated ''FTR''<ref name=pmid39607059>{{cite journal |authors=Sii S, Papa N, Yiu TW, Tempo J, Qu L, Perera M, Thompson I, Ischia J, Fleshner N, Smith E, Ranasinghe W, Bolton D, Woon DT |title=Utility of PSA free-to-total ratio for clinically significant prostate cancer in men with a PSA level of <4 ng/mL |journal=BJU Int |volume=135 |issue=4 |pages=550–556 |date=April 2025 |pmid=39607059 |doi=10.1111/bju.16597 |url=}}</ref>) and ''PSA free/PSA ratio'' | |||
* PSA in the serum can be found bound to protein or unbound (free).<ref>{{cite journal |authors=Cazanave Mora JM, Del Valle García R, Pérez López L, Bequer Ariza DC, Zulueta Rodríguez O, Melchor Rodríguez A, Hernández Pérez L, López Cisneros R, Arteaga Yera AL, Silva Cabrera E, Fernández Yero JL |title=Measurement of total and free prostate specific antigen (PSA) in human serum samples using an ultra-microanalytical system |journal=J Pharm Biomed Anal |volume=208 |issue= |pages=114470 |date=January 2022 |pmid=34798395 |doi=10.1016/j.jpba.2021.114470 |url=}}</ref> | |||
* High values of FTR have a lower risk of prostate cancer. | |||
** Modelling based on a cohort 406 men showed that: FTR ≤0.15 ~46% had prostate cancer versus FTR ≥0.20 ~22% had prostate cancer.<ref name=pmid39607059/> | |||
===Phoenix definition of biochemical failure=== | |||
Failure after radiotherapy: | |||
*PSA nadir + 2 ug/L.<ref name=pmid17968996>{{cite journal |authors=Abramowitz MC, Li T, Buyyounouski MK, Ross E, Uzzo RG, Pollack A, Horwitz EM |title=The Phoenix definition of biochemical failure predicts for overall survival in patients with prostate cancer |journal=Cancer |volume=112 |issue=1 |pages=55–60 |date=January 2008 |pmid=17968996 |doi=10.1002/cncr.23139 |url=}}</ref> | |||
===Immunostain=== | |||
*Relatively specific for prostate | |||
*May be found in normal pancreatic, salivary gland, Skene's glands and lactating breast tissue.<ref name=pmid21979599>{{cite journal |authors=Kelly P, McBride HA, Kennedy K, Connolly LE, McCluggage WG |title=Misplaced Skene's glands: glandular elements in the lower female genital tract that are variably immunoreactive with prostate markers and that encompass vaginal tubulosquamous polyp and cervical ectopic prostatic tissue |journal=Int. J. Gynecol. Pathol. |volume=30 |issue=6 |pages=605–12 |date=November 2011 |pmid=21979599 |doi=10.1097/PGP.0b013e31821713b6 |url=}}</ref> | |||
*In women, positive in up to 30-40% of breast cancers and also in tubulo-squamous polyps of the vagina. | |||
==Microscopic== | |||
Features - PSA immunostain: | |||
*Granular cytoplasmic staining. | |||
Notes: | |||
*May be very weak -- need to look at high power. | |||
<gallery> | |||
Image: Advanced prostate carcinoma - PSA -- high mag.jpg | Adv Pca - weak PSA - high mag. (WC) | |||
Image: Advanced prostate carcinoma - PSA -- very high mag.jpg | Adv Pca - weak PSA - very high mag. (WC) | |||
Image: Advanced prostate carcinoma - PSA - 2 -- high mag.jpg | Adv Pca - PSA - high mag. (WC) | |||
Image: Advanced prostate carcinoma - PSA - 2 -- very high mag.jpg | Adv Pca - PSA - very high mag. (WC) | |||
</gallery> | |||
==See also== | ==See also== | ||
*[[Prostate cancer]]. | *[[Prostate cancer]]. | ||
*[[Prostatic-specific acid phosphatase]]. | |||
*[[NKX3.1]]. | |||
==References== | ==References== | ||