PATHOLOGY

Correlation of minute (0.5 mm or less) focus of prostate adenocarcinoma on needle biopsy with radical prostatectomy specimen: role of prostate specific antigen density
Allan RW, Sanderson H, Epstein JI
Department of Pathology, Johns Hopkins Hospital, Baltimore, Maryland, USA
J Urol. 2003; 170: 370-2

• Purpose: Few studies have examined the radical prostatectomy followup of a minute focus of adenocarcinoma on prostate needle core biopsy.
• Materials and methods: We searched the surgical pathology data base (1999 to 2000) for patients with a minute focus of Gleason score 6 adenocarcinoma (defined as a single focus less than or equal to a 40x microscopic field) who subsequently underwent radical retropubic prostatectomy at our institution. Potentially insignificant tumors were defined as those with a radical prostatectomy tumor volume of less than 0.5 cc, Gleason score 6 or less and organ confined disease.
• Results: A total of 54 patients (mean age 58 years, range 45 to 70) were evaluated. The average number of prostate cores per biopsy was 6.3. All had Gleason score 6 by study design. Mean prostate specific antigen (PSA) was 6.0 (range 0.8 to 15). Average tumor volume at radical prostatectomy was 0.39 cc. Of the 54 tumors 24 (44%) were 0.1 cc or less. Two-thirds of the tumors were clinically potentially insignificant. Using a PSA density (PSAD) cutoff of 0.15 we identified 30 of 36 patients (83%) with potentially insignificant tumors. Of those with a PSAD of 0.15 or less with clinically significant tumors, 5 of 6 still had relatively small, organ confined tumors with Gleason score less than 7.
• Conclusions: In the era of PSA screening most patients with a minute focus of Gleason score 6 or less adenocarcinoma on needle biopsy had potentially insignificant tumors. However, one-third of patients had clinically significant tumors warranting definitive therapy. The smallest focus of cancer on needle biopsy is not a guarantee of a clinically insignificant tumor. PSAD may have some value within this group in guiding clinicians and patients as to the likelihood of having clinically insignificant tumors.
  
  
• Editorial Comment
  Epstein is the correspondent author of this paper from The Johns Hopkins Hospital. The study evaluated PSA density and pathologic findings in needle biopsies predictive of “insignificant” tumors in radical prostatectomies. In our opinion the term “insignificant” should not be used because it may imply that the tumor should be ignored. This is not the case. It means a minimal cancer judged by a volume of less than 0.5 cc representing an incipient phase either of a clinical or a latent carcinoma. Unfortunately there is not yet a marker for this distinction. A predictive positive value of 83% for minimal cancer ( < 0.5 cc) in radical prostatectomy was found using a PSA density (PSAD) cutoff of 0.15 or less and a minute focus of carcinoma in the needle biopsy on one core less or equal to a 40X microscopic field (about 0.5 mm) with no Gleason grade 4 or 5. This kind of study addresses a very important question regarding information to the patient. It is absolutely necessary that the patient be informed by the urologist in this circumstance that there is a probability of 83% for the cancer to be minimal (less than 0.5 cc) in the radical prostatectomy specimen. As a consequence of this fact and depending on how the specimen is processed there is a possibility around 5% to be very hard to find the cancer and even not to be found at all (DiGiuseppe JA et al.: Increasing incidence of minimal residual cancer in radical prostatectomy specimens, Am J Surg Pathol. 1997; 21: 174-8).

Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil