PATHOLOGY

Does pT2b cancer exist? Critical appraisal of the 2002 Tumor-Nodes-Metastasis (TNM) classification of prostate cancer
Eichelberger LE, Cheng L
Indiana University School of Medicine, Indianapolis, Indiana, USA
Mod Pathol. 2004; 17 (suppl. 1): 148A

• Background: Clinical and pathologic staging of prostate adenocarcinoma provides a method for assessing the extent of tumor and predicting patient prognosis. The American Joint Committee on Cancer (AJCC) TNM staging system has undergone recent revisions for stage T2 prostate tumors. T2 tumors are now subclassified asT2a (less than one half of one lobe involvement), T2b (more than one half of one lobe involvement), and T2c (bilateral involvement). Despite general acceptance of the system as a whole, controversy and uncertainty still exist in the application of the TNM staging system, particularly with use of the T2 staging subclassification. We analyzed the 2002 AJCC subclassification for stage T2 prostate cancers in a large series of radical retropubic prostatectomies.
• Design: The study population consisted of 369 prostate cancer patients treated by radical retropubic prostatectomy. None were treated by hormonal or radiation therapy prior to surgery. Radical prostatectomies were histologically evaluated by complete embedding and whole mount processing. Tumors were initially staged using the 1997 AJCC TNM system, and then reevaluated according to 2002 TNM staging guidelines.
• Results: The prostate weight ranged from 14 to 149 grams (median, 38 grams). Prostate cancers were multifocal in 312 cases (85%). The majority of the specimens were pathologic stage T2 (276, 75%). Using the 2002 TNM staging criteria, 54 (15%) of the tumors were stage pT2a, 222 (60%) were pT2c, 75 were (20%) pT3a, and 18 (5%) were pT3b. No pathologic stage T2b tumors were identified.
• Conclusions: Taking into consideration the average prostate weight (35 grams) as well as the predominance of tumor multifocality, it would be unusual to identify tumor involving more than one half of one lobe (approximately 8 cc), without involving the other lobe. We question the existence of a true pT2b tumor.
  
  
• Editorial Comment
  This is a very interesting study based on pathologic findings in the specimen of radical prostatectomies questioning the existence of pT2b tumors. None of a total of 369 cancers was stage pT2b. No case involved more than half of one lobe when cancer is unilateral.
  We were very curious about and checked this finding in 198 radical prostatectomies performed in our Institution. From the total of 198 specimens, cancer was bilateral in 174 (87.87%) and unilateral in 24 (12.12%). We use for tumor extent evaluation a point-count method published by us in International Braz J Urol. 2003; 29:113-120. In all of the 24 specimens with unilateral cancer, extension corresponded to less than half of the lobe. Our findings also question the existence of a true pT2b tumor.

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