by Kevin D. Huff, DDS, MAGD
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Adjunctive oral cancer screening systems enhance our ability as clinicians to perform a thorough oral exam. However, there are two distinct categories of adjunctive screening technologies. Systems such as the VELscope®, ViziLite® Plus, Orascoptic DK™, and Microlux™/DL are visualization aids. No tissue sampling is done with these. The Oral CDx BrushTest® and liquid-based cytology require minimally invasive tissue sampling.
Brush cytology does not yield a definitive diagnosis. Only a surgical biopsy allows for detailed histological analysis. However, some patients may be reluctant to undergo surgical biopsies for occult, early lesions discovered by conventional examination or with the use of visual adjunctive technology.
Sometimes, it may be helpful for a general dentist to support his/her rationale for referral to a specialist for a surgical biopsy with tissue sampling. In these cases, brush cytology can be very helpful for patient education and for strengthening our credibility of referrals to specialists. Currently, two systems are available that utilize brushes to collect cells from suspicious lesions, presumably from all of the epithelial layers, using a rotary or scrubbing motion with just enough pressure to bend the brush handle.
The Oral CDx system (CDx Laboratories, Inc., Suffern, N.Y.) is readily available through dental suppliers. Once collected on the patented brush, the tissue sample is smeared onto a glass slide, coded for identification chairside, and fixed with an alcohol-based solution. The brush and any residual cells are then discarded.
The sample slide, once fixed, is shipped to CDx Laboratories. A sophisticated computerized screening system identifies irregular cells, and then cytopathologists certify the results. The clinician who submitted the specimen receives a report from the cytopathologists at CDx Laboratories of “atypical, warranting further investigation,” “positive,” or “negative for epithelial abnormality,” along with a summary of what those reports may mean.
Alternatively, tissue samples may be submitted to one of several institutions, such as Tufts Oral Pathology Services in Boston, for liquid-based cytology. Although samples are collected through rotary brushing, instead of preparing the specimen chairside, the entire brush is placed in a vial containing a proprietary liquid alcohol-based medium. Those in favor of this system argue that it allows testing of the entire sample because the brush is not discarded until laboratory processing. The vial containing the brush and cells is then shipped to the laboratory for processing by SurePath protocol (TriPath Imaging, Inc., Burlington, N.C.).
The specimen vial is centrifuged, and the cells are placed on a glass slide for modified Papanicolaou staining. Each slide is examined microscopically by a board-certified oral pathologist. The submitting clinician receives a detailed report from the pathologist with a recommendation for appropriate follow-up therapy.
It is important to reiterate that none of the adjunctive screening technologies — visualization tools nor brush cytology — are, nor can they be, diagnostic. Definitive histological diagnoses are only possible by collecting, processing, and examining an actual piece of tissue. So, when and how is brush testing appropriate?
In my practice, all adjunctive technologies have their place. Every patient is examined conventionally and with a VELscope (although I have also used the other systems). If a lesion is discovered, I take my gloves and mask off and sit at or below the level of the patient. I say, “Mr. Patient, I'm a bit concerned about something I've found in your mouth. I'd really like to see you back in two weeks. If it's still there, I'll probably suggest that we send in a little piece of that area to see what it is for sure.”
Many times, patients are nervous about waiting two weeks. They want to know if there's anything to worry about right now. That's when brush cytology is indicated for peace of mind. However, I always tell the patient that if the lesion is present in two weeks, a biopsy will still be indicated. Sometimes, even if lesions persist for two weeks, patients are reluctant to accept a biopsy. In these cases, I might say to the patient, “I understand your reluctance, and that's normal. Would you let me rub a brush over that area and send it in to see if it is something to be concerned about?”
If lesions persist for 14 days, atypical results from cytology are typical. Brush cytology at this point only strengthens my case for biopsy. I have not had a patient refuse a biopsy once the recommendation has been well-founded by abnormal visual screening, abnormal clinical appearance, and abnormal cytology.
Kevin D. Huff, DDS, MAGD, is a practicing general dentist in rural Ohio, a private researcher, author, and dental educator. A clinical instructor at the Case School of Dental Medicine, he lectures nationally about oral cancer screening and biopsy techniques. Contact him at firstname.lastname@example.org, or on the Web at www.doctorhuff.net.