Flow cytometry for followup examinations of conservatively treated low stage bladder tumors

A series of 26 conservatively treated patients with low stage bladder tumors was examined later by outpatient cystoscopy, conventional cytology and flow cytometry. Based on those findings the patients were separated into 5 groups. In the 4 patients in group 1 all findings persistently were negative. The 4 patients in group 2 had initially normal cystoscopy with progressively more abnormal flow cytometry and intermittently positive cytology; they subsequently suffered tumors. The 10 patients in group 3 had positive cystoscopy and flow cytometry, and intermittently positive cytology. The 6 patients in group 4 had negative cystoscopy with intermittently positive cytology and persistently positive flow cytometry. In all 6 cases flow cytometry was more sensitive than conventional cytology in detecting early and, sometimes, cystoscopically occult neoplasms. In the 2 patients in group 5 cystoscopically visible papillomas and low grade papillary carcinomas were found with negative flow cytometry and negative or suspicious cytology. The papillary tumors in these 2 patients were believed to be composed principally of benign or atypical epithelium, with too few malignant cells to be detected by present flow cytometry techniques. Our preliminary results suggest that flow cytometry may be a valuable tool for followup of patients who have had conservatively treated low stage bladder tumors and are at risk for development of carcinoma. In addition, the techniques may be used to monitor changes in the proportion of benign and malignant cells and, thus, can be of help in following the course of newly forming papillomas, papillary carcinomas or carcinoma in situ in papillomas or flat epithelium.