Papillary urothelial neoplasms of low malignant potential - Clinical and biologic implications

BACKGROUND. Knowledge of the long term outcomes of patients with papillary urothelial neoplasms of low malignant potential (LMP) is limited. METHODS. The authors studied 112 consecutive patients who were diagnosed wi th papillary urothelial neoplasms of LMP (formerly Ta, World Health Organiz ation Grade 1 of 3 papillary urothelial carcinoma) at the Mayo Clinic betwe en 1958 and 1963. All histologic slides were reviewed and fulfilled the dia gnostic criteria of the 1998 World Health Organization/International Societ y of Urological Pathology classification system. RESULTS. Patient age at diagnosis ranged from 33 to 99 years (mean, 65 year s). The male-to-female ratio was 3:1. The mean follow-up was 12.8 years (ra nge, 0.1-35 years; median, 11.7 years). Twelve patients had biopsy-proven, noninvasive urothelial carcinoma; 17 patients had cystoscopically detected recurrences (all were treated by fulguration without biopsy); and 4 patient s developed invasive urothelial carcinoma (including 2 with muscle-invasive carcinoma). Twelve (75%) of 16 patients with biopsy-proven recurrence or p rogression had cancer dedifferentiation, which resulted in a diagnosis of h igher grade cancer than was indicated on initial biopsies. The mean interva l from initial diagnosis to development of invasive carcinoma was 13.3 year s (range, 10-14 years). Three patients died of bladder cancer. CONCLUSIONS. Patients with papillary urothelial neoplasms of LMP have incre ased risks of local recurrence, progression, and death from bladder carcino ma. Long term clinical follow-up may be indicated for patient management. [ See editorial on pages 1890-2 and related article on pages 2098-101, this i ssue.] Cancer 1999;86: 2102-8. (C) 1999 American Cancer Society.