Background: The 1992 American Joint Committee on Cancer and International Union Against Cancer TNM classification system for prostate cancer includes categories for the increasingly common nonpalpable cancers detected by serum prostate specific antigen (PSA) levels and transrectal ultrasonography (TRUS), but few details have been published about the pathologic features and prognosis of such cancers.
Methods: We analyzed the clinical and pathologic features of 400 patients with clinical Stages T1-T3, NO or NX, M0 cancer treated with radical prostatectomy. We compared volume, grade, extension, and prognosis of cancers detected by PSA or TRUS to those detected by the traditional techniques of transurethral resection (TURP) or digital rectal examination.
Results: As clinical stage increased in the TNM classification, the volume, grade, and frequency of extraprostatic spread increased significantly. The 33 nonpalpable, nonvisible tumors detected because of an elevated PSA (T1c) were similar in size and frequency of extension to TURP-detected (T1a-b) cancers, but more often were poorly differentiated (52% vs. 22%) (P < 0.03). No T1c cancer has recurred to date. Nonpalpable T2 cancers detected by TRUS (n = 42) were significantly more likely (47% vs. 18%) to extend outside the prostate than were T1c cancers. Compared to palpable T2 cancers, TRUS-detected T2 cancers were smaller but were similar in grade, extension, and prognosis. T3 cancers were extensive and recurred rapidly; only 6% were confined to the prostate. In contrast, 24% of the T1 and 57% of the T2 cancers were not confined (> or = pT3), but only 6-9% of T1-T2a cancers exhibited advanced pathologic features (seminal vesicle invasion or lymph node metastases), compared with 26% of the T2b-c cancers.
Conclusion: The new TNM staging system provides appropriate new categories for inclusion of nonpalpable cancers detected by PSA and ultrasound. This new classification is logical and generally reflects the pathologic extent and prognosis of these tumors, although cancers in the advanced T2 categories are often more extensive.