The value of DNA image cytometry combined with brush routine cytology in diagnosing indeterminate biliary strictures: A large sample size retrospective study.

Background and Aim: Brush cytology is widely applied to diagnosis indeterminate biliary stricture but suffer from low sensitivity. Changes in DNA content are a character of malignant cell and can be detected by DNA image cytometry (DNA‐ICM). The study aimed to estimate the value of routine cytology (RC), DNA‐ICM, and their combination in diagnosing indeterminate biliary strictures. Methods: A total of 362 patients who underwent both RC and DNA‐ICM tests were analysed. Their results were retrospectively applied to final diagnoses. Diagnostic values were compared among RC, DNA‐ICM, and their combination based on the location of strictures. Results: The DNA‐ICM and combination of two methods had higher diagnostic accuracy than RC in all strictures (63.3% vs 42.3%, P < 0.001, 64.36% vs 42.3%, P < 0.001) and in distal strictures (65.36% vs 42.81%, P < 0.001, 66.01% vs 42.81%, P < 0.001). But in proximal strictures, DNA‐ICM showed no superior (51.8% vs 42.81%, P = 0.184). Combination of two methods was not fully significant superior to RC in proximal strictures (55.36% vs 39.29%, P = 0.089). After classification of "suspicious for malignancy" as positive for malignancy, the diagnostic accuracy of DNA‐ICM was still higher than that of RC in all strictures (63.3% vs 51.9%, P = 0.002) and in distal strictures (65.36% vs 52.29%, P = 0.001). Combination of two methods was no superior to DNA‐ICM alone (64.36% vs 63.3%, P = 0.757). The utilization of DNA‐ICM was more accurate in distal strictures than in proximal strictures (65.36% vs 51.8%, P = 0.017). Conclusion: DNA‐ICM is an objective and effective addition tool with RC, especially in distal strictures. The combination of DNA‐ICM and RC showed no superior to DNA‐ICM alone but could improve diagnostic accuracy to RC in proximal strictures although not fully significant. [ABSTRACT FROM AUTHOR]