Acridine‐orange flow cytometry of urinary bladder washings for the detection of transitional cell carcinoma of the bladder: The influence of prior local therapy

Analysis of cellular DNA and RNA contents of 249 bladder irrigation specimens from 129 patients with a history of transitional cell carcinoma (TCC) of the bladder was performed using acridine‐orange flow cytometry (FCM). Washings from patients with prior intravesical chemotherapy or radiation therapy were compared to those from patients with no history of treatment other than tumor resection to evaluate the reliability of FCM for the detection of tumor and the influence of prior local therapy on that reliability. Five FCM patterns were defined on the basis of DNA and RNA indexes in relationship to peripheral blood lymphocytes. FCM results were compared to cytologic findings in 237 cases, cystoscopic findings in 230 cases, and histologic data in 99 cases. Presence of a single diploid stem line was associated with absence of bladde tumor in 71% of cases from patients treated with surgery alone or with radiation therapy, but there was residual tumor in 53% of patients exposed to prior local chemotherapy. An elevated RNA content in a diploid cell population did not provide additional diagnostic information. Presence of an aneuploid stem line was associated with tumor in 85% of cases, regardless of prior therapy. Aneuploidy predicted the appearance of tumor in four of six patients with a negative cystoscopy. Tetraploidy (>10% of total cell population) was associated with tumor in 79% of patients treated with surgery alone, whereas no tumor was found in more than 50% of patients who had undergone prior chemotherapy or radiation therapy. This study stresses the importance of prior treatment history in evaluating the results of DNA‐FCM for bladder cancer. It demonstrates the unreliability of FCM diploid and tetraploid cell populations in patients previously treated by local chemotherapy or radiation. However, it also supports prior observations that DNA‐aneuploidy and DNA‐tetraploidy are useful for detecting and predicting bladder cancer in patients submitted to surgery alone.