T1 G1 urinary bladder carcinoma: fact or fiction?

OBJECTIVES

To record the occurrence of well-differentiated bladder carcinoma reported as T1 G1 to the Swedish Urinary Bladder Cancer Registry, to review the staging and grading of the carcinomas and to scrutinize the validity of the data on T1 G1 tumours reported to the registry during the period 1997-2000.

MATERIAL AND METHODS

The primary histopathological diagnoses of 98 cases of well-differentiated bladder carcinoma reported to the Registry were compared with the data delivered by the local urologists. Also, the histopathology slides were obtained from the local laboratories and re-examined.

RESULTS

Fifty-five cases had been erroneously reported to the Registry as T1 tumours by the urologists, even though they were clearly described as non-infiltrating G1 tumours by the pathologists. The results of the re-examination of the pathology slides were concordant with the judgements of the local pathologists in only 50% of cases (20 stage T and 29 grade G tumours). Most importantly, the re-evaluation did not reveal a single invasive G1 tumour. Simply by providing the urologists with information about this problem, it was possible to reduce the number of errors in the reports from 27 in 1997 to only five in 2000.

CONCLUSIONS

Well-differentiated urothelial carcinoma (G1) has no propensity to infiltrate the bladder mucosa. For investigating specific problems the data collected in the Swedish Urinary Bladder Cancer Registry have to be validated.