COMMENTARY

Adjunctive Cytologic Testing for Oral Cavity Lesions

Joel M. Laudenbach, DMD

Disclosures

December 15, 2017

Assessment of Oral Cavity Lesions

Various adjunctive tests are commercially available for primary, secondary, and tertiary oral health clinicians who wish to assess oral cavity lesions beyond the conventional visual and tactile clinical examination in adult patients. Clinical decision-making can be a challenge for lesions that appear innocuous (not suspicious), potentially malignant (PM), and malignant (M), for a variety of reasons.

The gold-standard technique to make an oral diagnosis while definitively ruling out PM/M diseases is surgical biopsy coupled with oral histopathology examination. In some clinical scenarios, patients refuse referral to a specialist and/or surgical biopsy, and the dentist must make a decision about whether to use an adjunctive test.

Lingen and colleagues[1] reviewed the available evidence for multiple adjunctive tests, including cytologic, vital staining, autofluorescence, tissue reflectance, and salivary. The authors reviewed evidence to assess how helpful these tests are when used solely to triage the need to biopsy oral cavity lesions "and not as replacement for biopsy."[1]

Diagnostic test accuracy studies and randomized controlled trials were included, involving adult patients 18 years or older. Although it would be ideal to include only studies in the context of primary dental care, available studies in secondary and tertiary settings were also included. If no gold-standard criterion was used, those studies were excluded. In primary care settings, the authors estimated that the prevalence of PM/M oral cavity diseases is low: 0.25%-2.0%.

Cytologic testing, including commercially available products such as Oral CDx®,[2] OralCyte®,[3] and ClearPrep OC®,[4] is not a surgical scalpel biopsy procedure. Some of these cytologic tests are considered transepithelial because the particular brush system used harvests epithelial cells from superficial, intermediate, and basal cell layers when performed properly. Interpretation and reporting of results varies by manufacturer.

How helpful is cytologic testing to primary providers when triaging the need for biopsy?

For innocuous (not suspicious) oral cavity lesions, cytologic testing had 0.96 sensitivity and 0.90 specificity. For the oral cavity lesions suspected to be PM/M, cytologic testing had 0.92 sensitivity and 0.94 specificity. It is important for clinicians to recall these definitions: Sensitivity is "the ability of a test to help identify those with the disease correctly, also known as the true-positive rate,"while specificity is "the ability of a test to help identify those without the disease correctly, also known as the true-negative rate."[5]

Viewpoint

These new true-positive and true-negative rates for cytologic testing are somewhat encouraging but must be interpreted with caution when applied to clinical use. There is another new article, published in October 2017, offering new evidence-based clinical practice guidelines (CPG) for the evaluation of PM disorders in the oral cavity.[5] This new CPG appears to give some support to using cytologic testing only when certain patient scenarios arise: when patients decline referral to a specialist or refuse biopsy recommendations. Readers are strongly encouraged to become familiar with the new CPG manuscript.[5]

If a clinician elects to use cytologic testing, he/she should be keenly aware of the limitations of each brand of test, especially in primary care dental settings. The clinician should also be confident that the patient is fully informed about the limitations of the test. Tell patients specifically that cytologic testing is not a biopsy and not a replacement for biopsy, and has been associated with false-positive/false-negative results and delays in diagnosis/treatment of oral cavity dysplasia/neoplasia.

The patient should also understand and commit to long-term clinical follow-up care as recommended by the managing clinician. The re-evaluation program/schedule with patients who elect to have cytologic testing must be firm, consistent, and well documented. It is prudent to remind all patients that they can follow up early at any time and can elect to proceed with biopsy and/or specialist referral at any time.

Clinicians may consider obtaining written informed consent to ensure that patients are well informed that cytologic testing is not the gold standard, and that surgical biopsy along with histopathologic assessment are the only procedures that can definitively rule out dysplasia and neoplasia.

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