The importance of the depth of invasion in stage T1 bladder carcinoma: a prospective cohort study

We studied the depth of invasion in the lamina propria in all patients with primary stage T1 bladder cancer in a geographical region and related the findings to the long-term prognosis.

All 121 primary stage T1 tumors diagnosed in western Sweden between 1987 and 1988 were analyzed with respect to the depth of invasion in relation to the lamina muscularis mucosae. All clinical records were reviewed in 1994 and 1995.

More than 90% of the histopathological specimens could be separated into superficially (pT1a) or deeply (pT1b) invasive stage T1 tumors. Grade 3 tumors were significantly more common among patients with stage pT1b disease (79 versus 40%, p < 0.001). Patients with stage pT1b grade 3 cancer had a higher progression rate (58 versus 36%, p > 0.05) and an almost doubled risk of dying of bladder carcinoma compared to those with stage pT1a grade 3 disease (45 versus 23%, p > 0.05). Carcinoma in situ at the primary operation was associated with an impaired prognosis in patients with grade 3 tumors regardless of the depth of invasion in the lamina propria.

The prognosis is poor in patients with deep lamina propria invasion (stage pT1b) treated with transurethral resection alone. Patients treated with radical cystectomy had excellent survival regardless of the depth of invasion in the lamina propria. Radiotherapy was associated with poor survival.