Diagnostic problems of urine cytology on initial follow-up after intravesical immunotherapy with Calmette-Guérin bacillus for superficial bladder cancer.

After transurethral resection or biopsy, patients with recurrent bladder cancer or in situ carcinoma were given topical immunotherapy with low-dose Calmette-Guérin bacillus (BCG). In the recurrence-free interval they were treated with BCG monthly for 1 year and then every 3 months for the next year. Cytological analysis was always performed concomitant with the administration of immunotherapy. In order to evaluate the therapeutic success, cystoscopy and biopsy were performed after the first cycle of BCG and then every 3 months. At the start of topical therapy with BCG, a great increase in the number of inflammatory cells was seen. In urothelial cells the nuclei were enlarged; they were hyperchromatic with sometimes increased and prominent nucleoli, anisocaryosis and a distorted nucleus-plasma ratio. These cytological findings were also made 1 year after initial therapy and slowly diminished in the 2nd year during immunotherapy at 3-month intervals. The accuracy of urine cytology for carcinoma in situ is 80%. Interpretation of cytology in the recurrence-free interval was impaired. When doubtful, the recurrence of a carcinoma in situ under maintenance therapy with BCG must be proved by biopsy.