Dr. Tyler Potter and colleagues’ March JADA letter to the editor was highly critical of the most comprehensive, nationwide oral cancer campaign ever conducted in the United States and used the opportunity to disparage the brush biopsy technique.
In the past year alone, dentists have used the brush biopsy to detect well over 2,000 oral dysplasias and carcinomas among lesions that would not have aroused sufficient suspicion to biopsy prior to the advent of this test. The emphasis on lives saved as a result of the oral cancer campaign was recently communicated by the ADA president and executive director to all ADA members.
The many comparisons made by the authors between incisional biopsy and brush biopsy suggest that they mistakenly view the two biopsy modalities as competitive methods for testing the same spectrum of abnormality. The authors fail to appreciate the fact that the brush biopsy is utilized to test the spectrum of benign-appearing lesions that have been either "watched" or ignored in the past and that this use has already saved many lives.
The authors suggest that all five articles on the brush biopsy technique,1–5 published in peer-reviewed journals by oral pathologists from prestigious universities, were written by academicians who had a financial interest in the company providing the brush biopsy service.
None of the authors who has participated in clinical studies or published articles on the brush biopsy technique has any financial interest in, commercial associations with, stock in or other equity ownership in CDx Laboratories. This insinuation is outrageous.
The authors contend that the multicenter trial,2 published as the cover story in the October 1999 JADA, contained design flaws and statistical errors. They obviously are unaware that independent statisticians reviewed the design of the study and all of the results, and that statisticians and scientists at the ADA, before granting OralCDx the Seal of Acceptance, analyzed the raw data rigorously.
Additionally, the CDx technology is currently in clinical trials for the early detection of laryngeal, pharyngeal and esophageal cancer, and clinical protocols identical to the OralCDx protocol have been approved by review committees at more than 15 U.S. medical schools. The authors’ suggestion that the "sensitivity and specificity data [are] incomplete" is totally unfounded since, as is clearly stated in the publication of the clinical trial and confirmed by statisticians, only those brush biopsies with matching scalpel biopsies were used to determine OralCDx sensitivity and specificity.
To suggest that the brush biopsy is painful and may be as painful as an incisional biopsy also is incorrect, since every publication based on clinical experience with the brush biopsy technique describes it as painless.1–5
Although they claim that the brush biopsy is "a variation of the cytologic smear technique," the authors overlook the fact that studies employing oral cytology resulted in false negative rates of 30 percent to 50 percent,6,7 compared with the 96 percent sensitivity demonstrated with the OralCDx computer-assisted brush biopsy.
The letter writers’ greatest misunderstanding is revealed in their statements that "mucosal abnormalities are clinically recognizable" and that the brush biopsy is, therefore, "a test that confirms what is clinically visible." The literature is replete with documentation of the fact that precancers and early oral cancers often appear clinically identical to commonly encountered benign lesions.8–10
In fact, the oral brush biopsy was developed to enable dentists to evaluate countless such lesions seen in their patients on a routine basis. Indeed, in the multicenter trial, 29 benign-looking lesions judged harmless in appearance by experienced academic clinicians were identified as precancers and cancers only as a result of the use of the brush biopsy test.
In contrast to the numerous oral pathologists, oral surgeons and oral medicine specialists who have presented hundreds of lectures in which they have explained the value of the brush biopsy to thousands of dentists, these authors fail to understand that the brush biopsy is intended to evaluate benign-appearing oral lesions and not those distinguished by signs and symptoms of malignancy, which are clear signals for immediate incisional biopsy. Tens of thousands of U.S. dentists who have adopted the brush biopsy as a diagnostic aid have understood clearly both the message of early detection publicized by the ADA and the potential benefits to their patients.
It is unfortunate that Dr. Potter and his colleagues have not appreciated the positive impact that the brush biopsy already has had on the health of the thousands of patients diagnosed with oral precancers and cancers. The care and diligence exercised by dentists in using this tool to evaluate a spectrum of lesions whose benign appearance previously would not have directed them for biopsy serves the public well.
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