Prospective, blinded comparison of cytology and DNA-image cytometry of brush biopsies for early detection of oral malignancy.

OBJECTIVES: Adjunctive techniques like DNA image cytometry (DNA-ICM) have been attributed to enhance the diagnostic performance of oral brush biopsies. The aim of the study was an evaluation of brush biopsies, analysed according to morphological criteria and by DNA-ICM vs. histological findings in a blinded prospective trial.

MATERIALS AND METHODS: Eighty eight brush biopsies of 70 patients were sampled. Only clinical suspicious but not evident malignant oral lesions were included. Clinical diagnosis was leukoplakia (n = 36), lichen planus (n = 18), verruciform erythroplakia (n = 12), erythroleukoplakia (n = 9), erosion (n = 7) and induration (n = 6). Evaluation was conducted via histology, cytology and DNA-ICM.

RESULTS: Histological diagnosis revealed eight cases of squamous intraepithelial dysplasia (SIN 1 n = 6, SIN 2 n = 2), four cases of carcinoma-in situ and 25 cases of oral T1-cancer. Remaining cases were leukoplakia (n = 28), lichen planus (n = 15) and local inflammation (n = 8). Brush biopsy detected malignant lesions including SIN>1 with a sensitivity of 55% and a specificity of 100%. DNA-ICM had a sensitivity of 70% and a specificity of 100%. The combination of both methods showed a sensitivity of 76% and a specificity of 100%. The predominant reason for false negative results were sampling errors with insufficient cells (86% in brush biopsy and 100% in DNA-ICM).

CONCLUSION: DNA-ICM has the potential to substantially improve the sensitivity of a pure morphological interpretation of oral brush biopsies. Method inherent sampling errors may be accountable for a lower sensitivity compared to conventional histological diagnosis. Therefore, DNA-ICM should not be used to rule out malignancy, when lesions are already clinically suspicious for oral cancer.