Given my explanation and widely publicized opinion on the improper use of the prostate-specific antigen (PSA) test for screening asymptomatic men for prostate cancer—most recently expressed in a feature article in The ASCO Post (August 15, 2012)—I was pleased to read that Drs. James Mohler and Donald L. Trump share my concern in what they describe as “apprehensions about improper use of PSA testing and overtreatment of prostate cancer.” However, beyond this, a scientific misunderstanding continues, perpetuated by Dr. Mohler, and now Dr. Trump, as to who did what and when on the subject of PSA.
Chronology Reconsidered
Drs. Mohler and Trump’s claim that “Dr. Ablin had no role in the discovery of the molecule now known as PSA” is not only patently false but also ironic, considering a direct quote from Milestones in Urology: Advances in Patient Care, a commemorative calendar and monograph published in 2001 by the American Urological Association (AUA): “The PSA test is a product of many minds collaborating over many decades. In 1970, immunologist R. J. Ablin, of the State University of New York, Buffalo, initially observed PSA. Roswell Parks’ T. Ming Chu, with other investigators set out to extend Ablin’s observations.”
Moreover, the consensus from any of a number of papers in the literature is clear and unified, eg, in quoting Polascik et al1: “PSA was first identified in human prostate tissue extracts in 1970 [Ablin et al: J Reprod Fert 22:573-574, 1970], purified and characterized in 1979 [Wang et al: Invest Urol, 17:159-163, 1979] … ” The PSA test was subsequently initiated by Papsidero et al.2 I have never claimed a role in the test’s development.
Drs. Mohler and Trump’s statement—“Dr. Ablin discovered a ‘prostate-specific antigen’ that appears in normal prostate tissue, but [Chu] identified and purified another protein … from normal, benign, and malignant human prostate tissue,”—is once again thoroughly contradicted by the literature: Ablin et al3,4 referenced ongoing studies in the benign and malignant human prostate, which were subsequently reported by Ablin.5
Further, Drs. Mohler and Trump assert that, “Dr. Ablin’s antigen was found only in the normal prostatic tissue,” while Dr. Chu’s PSA is found not only in prostate tissue but also in prostatic fluid and semen, and they try torturing their assertion into fact by referencing published exchanges between Chu and me. There is either an incongruity in semantics regarding what our studies actually showed or a misunderstanding of the results by Drs. Mohler and Trump. In this regard, a subsequent paper by Wang et al6 concluded that PSA in seminal plasma originated from prostatic fluid, which is what I demonstrated in Ablin et al.3,4
Volumes of Articles
Surprisingly, Drs. Mohler and Trump rolled out the tanks in comparing Chu’s impressive “practice-changing” publishing history against “the paucity of material supporting Dr. Ablin’s claims.” I can cite volumes of articles in journals such as Cancer, Urology, Cancer Treatment Reviews, Prostate, etc, that attribute the discovery of PSA to me. Again, the physics of their posture is wrong, because no amount of volume can displace a fact that is indelible in the literature: I discovered PSA.
Given Drs. Mohler and Trump’s anxiety over erroneous information, perhaps they should look inward at the initial report by Chu7 in what was described as prostate tissue–specific antigen. Therein, Wang et al stated that the prostate tissue–specific antigen they identified “was not of glycoprotein nature” and had “a molecular weight of 220,000 Daltons” (22 kilodaltons [kDa]). This finding starkly contrasts with their 1979 paper in Investigative Urology,8 in which they affirmed that prostate tissue–specific antigen is a glycoprotein with a molecular weight of 33 kDa.
Additionally, Wang et al7 claimed to have identified a prostate tumor–specific antigen! If that were true, you can be certain that all of us of still looking for a prostate tumor–specific antigen would have heard of it. To my knowledge, it has not yet been identified.
Remaining Optimistic
Redressing Drs. Mohler and Trump’s arguments for using PSA testing as a diagnostic tool is beyond the scope of this reply. That said, I remain firm: Routine PSA screening in asymptomatic men is a national health-care disaster. The U.S. Preventive Services Task Force, along with a growing number of scientists and clinicians concur. Drs. Mohler and Trump will likely continue their efforts to discredit my role in the PSA saga—casting doubt on the messenger is an age-old ploy to cast doubt on the message. Through it all, however, I remain optimistic that unbiased science will eventually prevail, and the misuse of the PSA molecule I discovered in 1970 will come to an end. ■
Richard J. Ablin, PhD, DSc (Hon)
Department of Pathology
University of Arizona
College of Medicine
The Arizona Cancer Center
and BIO5 Institute
Tucson, Arizona
References
1. Polascik TJ, Oesterling JE, Partin AW: Prostate specific antigen: A decade of discovery—what we have learned and where we are going. J Urol 162:293-306, 1999.
2. Papsidero LD, Wang MC, Valenzuela LA, et al: A prostate antigen in sera of prostatic cancer patients. Cancer Res 40:2428-2432, 1980.
3. Ablin RJ, Soanes WA, Bronson P, et al: Precipitating antigens of the normal human prostate. J Reprod Fert 22:573-574, 1970.
4. Ablin RJ, Bronson P, Soanes WA, et al: Tissue- and species-specific antigens of normal human prostatic tissue. J Immunol 104:1329-1339, 1970
5. Ablin RJ: Immunologic studies of normal, benign, and malignant human prostatic tissue. Cancer 29:1570-1574, 1972.
6. Wang MC, Loor RM, Li SL, et al: Physico-chemical characterization of prostate antigen purified from human prostate gland and seminal plasma. IRCS J Med Sci 11:327-329, 1983.
7. Wang MC, Valenzuela LA, Murphy GP, et al: Tissue specific and tumor specific antigens in human prostate. Fed Proc 36:1254, 1977.
8. Wang MC, Valenzuela LA, Murphy GP, et al: Purification of a human prostate specific antigen. Invest Urol 17:159-163, 1979.
