The utility of toluidine blue application as a diagnostic aid in patients previously treated for upper oropharyngeal carcinoma

Objectives. This study evaluated the utility (usefulness) of toluidine blue application as an aid to the recognition and diagnosis of clinically evident lesions in a series of patients previously treated for oral cancer and monitored in a cancer center. In addition to increased risk of recurrence of cancer or new second primary lesions, patients who have had previous treatment for oropharyngeal cancer may be more difficult to assess because of tissue changes that occur as a result of previous radiation therapy. Study design. Patients with a history of oral malignancy were assessed by clinical examination followed by application of toluidine blue. Biopsy sites were determined on the basis of unaided visual examination and by the findings on toluidine blue application. Biopsy specimens were reviewed by a pathologist blinded to the clinical findings. Results. Unaided clinical examination identified 78% of carcinoma in situ or invasive malignant lesions compared with toluidine blue application, which identified all (100%) carcinoma in situ or invasive malignant lesions (p = 0.02) and produced no false-negative findings. No differences were found between clinical examination and toluidine application in the detection of dysplastic lesions. Conclusion. Toluidine blue retention was seen in all cases of carcinoma in situ and invasive carcinoma, and no false-negative findings were seen with toluidine blue. When used by a trained and experienced clinician in a cancer center, toluidine blue was a valuable visual aid to clinical examination of oral mucosal lesions.