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

BACKGROUND AND OBJECTIVE: Brush cytology is widely applied to diagnosis indeterminate biliary stricture but suffer from low sensitivity. Changes in DNA content is 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 analysis. Their results were retrospectively applied to final diagnoses. Diagnostic value were compared among RC,DNA-ICM and their combination based on location of strictures.

RESULT: The DNA-ICM and combination of 2 methods had higher diagnostic accuracy than RC in all strictures(63.3% vs 42.3%,P<0.001,64.36% vs42.3%，P<0.001) and in distal strictures(65.36% vs 42.81%,P<0.001,66.01%vs42.81%,P<0.001). But in proximal strictures, DNA-ICM showed no superior(51.8% vs42.81%,P=0.184). Combination of 2 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 2 methods was no superior to DNA-ICM alone (64.36%vs63.3%,P=0.757). The utilize of DNA-ICM was more accuracy 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 though not fully significant.