The usefulness of the level of the muscularis mucosae in the staging of invasive transitional cell carcinoma of the urinary bladder.

The initial biopsy specimens from 50 patients with high-grade invasive transitional cell carcinoma of the urinary bladder were evaluated for depth of invasion. Stages were assigned according to the following system: T1A, invasion of connective tissue superficial to the level of the muscularis mucosae; T1B, invasion to the level of the muscularis mucosae; T1C, invasion through the level of the muscularis mucosae but superficial to the muscularis propria; and B, invasion into the muscularis propria. Follow-up from the Yale Tumor Registry at a median time of 4.6 years showed that tumors invasive to levels T1A and T1B had a 75% 5-year survival, but tumors invasive through the level of the muscularis mucosae but apparently superficial to the muscularis propria (level T1C) had an 11% 5-year survival, which was comparable with the survival of patients with tumors invasive of the muscularis propria. This study suggests the prognostic importance of assessing the depth of invasion in initial biopsy specimens, even when the specimens lack a muscularis propria.