Carcinoma of the Bladder In Situ

To the Editor:—  In a recent summary article on cancer of the urinary bladder (206:1761, 1968) there is a total absence of information on some of the newer developments in the understanding of the natural history of this disease. The concepts of carcinoma in situ of the bladder and the cytologic diagnosis of bladder cancer during the preclinical stages of the disease were ignored. Yet considerable evidence has been presented from this laboratory that sessile nonpapillary carcinoma in situ constitutes a very significant stage in the development of cancer of the bladder, both in hospital populations and in industrial workers.^1-4 The same lesion often precedes recurrent carcinoma of the bladder following treatment. Such lesions, whether primary or secondary, cannot be accurately identified by cystoscopic examination. Diagnosis rests on cytologic evaluation of the urinary sediment combined with multiple biopsies of the bladder. The aggressive treatment of these lesions may prove