Carcinoma in situ of the urinary bladder. Clues to host involvement in human carcinogenesis

Carcinoma in situ (CIS) of the urinary bladder is a neoplasm of uncertain biologic behavior. It rarely occurs as the primary disease and exists most often in association with high grade, invasive tumors. The unfavorable prognosis ascribed to CIS may not be due to tumor-related factors but to low host resistance or to host-tumor relationships established for previous or co-incident invasive cancers. The scant available evidence indicates that a large proportion of patients with primary CIS have a low frequency of muscle invasion and death from disease.

Of 2000 patients with bladder neoplasms in our pathology files and tumor registry, 102 had CIS confirmed on histologic review. There were 29 cases of primary CIS and 73 cases of secondary CIS. These cases were compared, with an emphasis on patient outcome.

The data indicate that primary and secondary CIS are histologically identical lesions whose effect on patients is related mainly to the presence of multifocal disease, often associated with previous or coincident invasive cancers. Progression or death from disease is unusual among patients presenting with primary CIS but common among individuals with CIS associated with other bladder cancers.

The authors suggest that the appearance of urothelial CIS identifies patients with at least localized resistance to the development of invasive bladder cancer. The degree of patient resistance to carcinogenic events leading to bladder carcinoma is manifested by the type, grade, and stage of their initial neoplasms.