FIG. 20:  This Figure shows similar results from a study of data from patients who were treated in Sheffield for low-risk disease.^[22]  Out of 3633 new primary bladder cancers, 699 were low-grade non-muscle-invasive (G1pTa) tumors (which in the 1973 WHO criteria in use in the UK at the time these were classified as Grade I^[16]).  The diagnoses were annotated by clinical outcome, with a median follow-up of 61 months. 

Almost one third (28.5;%) of these patients’ tumors had a local recurrence at a median of 13.5 months.  Metastasis or progression to invasive tumor occurred in 2.6% of patients and high-grade progression developed in 4.7% of patients.  Survival was excellent in these low-risk patients, with the cancer-specific mortality of 2.4% at 55 months  However these were patients with competing risks such as heavy smoking and occupational exposure, so many developed cardiopulmonary disease, and as seen in Panel D, overall mortality was 34.6%, meaning that many patients were dying of other causes.