Should pathologists continue to use the current pT2 substaging system for reporting of radical prostatectomy specimens?

UROLOGICAL SURVEY

Pathology

Should pathologists continue to use the current pT2 substaging system for reporting of radical prostatectomy specimens?

Billis A, Meirelles L, Freitas LL, Magna LA, Ferreira U

Department of Anatomic Pathology, School of Medicine, University of Campinas, Unicamp, Brazil

Mod Pathol. 2010; 23 (suppl 1): 179A

BACKGROUND: During the International Society of Urological Pathology (ISUP) consensus conference on handling and staging of radical prostatectomy specimens, 65.5% of the attendants answered that the current pT2 susbstaging system should not be used. Answering to another question, 63.4% favored to be reduced to two categories based on studies showing that pT2b does not exist. There was no consensus in regard to a minimum size for a second tumor to be considered for the whole case to be classified as pT2c as well as in regard to the definition of index tumor. We compared clinicopathologic findings and biochemical progression following surgery classifying pT2 patients into two categories.

DESIGN: The study was based on whole-mount consecutive surgical specimens from 142 patients with organ confined cancer. Using a semiquantitative method for evaluation of tumor extent, 10 positive points corresponds roughly to a 0.5ml tumor. We considered pT2a/pT2b substage (group 1) whenever a tumor presented > 10 positive points on only one side and pT2c whenever presented > 10 positive points on each of right and left side (group 2). The variables analyzed were: age, preoperative PSA, clinical stage, Gleason score on needle biopsy, and biochemical progression following surgery defined as PSA > 0.2ng/mL. The data were analyzed using the Mann-Whitney test, and the Kaplan-Meier product-limit analysis using the log-rank test for comparison between the groups.Results: Substage pT2a/pT2b corresponded to 84/142 (59.2%) patients and substage pT2c to 58/142 (40.8%) patients. There was no statistically significant difference between the groups in relation to: age (p = 0.30), preoperative PSA (p = 0.13), clinical stage (p = 0.34), and Gleason score on needle biopsy (p = 0.27). In 5 years of follow-up, 61% of patients pT2a/pT2b and 71% of patients pT2 were free of biochemical progression (log-rank, p = 0.68).

CONCLUSIONS: There was no significant difference for several clinicopathological variables and time of biochemical progression following surgery between patients with stage pT2a/pT2b and patients with stage pT3c. The results of this study favor to discontinue using the current pT2 substaging system for reporting of radical prostatectomy specimens.

Editorial Comment

In 1997, the TNM staging of T2 prostate cancers was divided into T2a (unilateral tumor) and T2b (bilateral tumor). In 2002 and now in 2010, T2 stage was substaged as in 1992, i.e., into 3 groups: T2a (unilateral tumor, less than half lobe), T2b (unilateral tumor, more than half lobe), and T2c (bilateral tumor). The clinical staging of T2 prostate cancers gives a good prognostic information. Time of biochemical (PSA) recurrence shows significant difference among the 3 groups. The clinical staging is a reflection of the detection methods employed and the substaging of clinical stage T2 prostate cancers is largely based on the extent of the abnormality palpated during a digital rectal examination (DRE) or shown during transrectal ultrasonography (TRUS) in each half of the prostate.

In a Consensus Meeting held during the United States and Canadian Academy of Pathology meeting in Boston 2009, 65.5% of the uropathologists present answered that the current pathologic T2 substaging should not be continued. Why the pathologic T2 substaging should be discontinued?

In contrast to clinical substaging of T2 cancers, pathological substaging does not convey prognostic information. This happens because prostate cancer is essentially a multifocal tumor. In general, there is a larger tumor (index tumor) but almost always, other foci scattered along the gland. Therefore, a large unilateral tumor palpated by the urologist (cT2b) is always bilateral in the surgical specimen (pT2c) (1-3). It has been argued that the prognostic significance of clinical substaging by DRE and TRUS of T2 cancers is a direct effect of understaging (4). The paper surveyed was a platform presentation at the 99th Annual Meeting of the United States and Canadian Academy of Pathology held in Washington DC, 2010, and is supported by several other previous studies (5-8). The conclusions included no significant difference for several clinicopathological variables and time of biochemical progression following surgery between patients with pathologic stage T2a/pT2b and patients with pathologic stage T3c. The results of the study favor to discontinue using the current pathologic T2 substaging system for reporting of radical prostatectomy specimens.

Dr. Athanase Billis

Full-Professor of Pathology

State University of Campinas, Unicamp

Campinas, São Paulo, Brazil

E-mail: [e-mail]

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Publication Dates

• Publication in this collection
  31 May 2010
• Date of issue
  Apr 2010