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.