Chemistry: molecular biology and microbiology – Apparatus – Including measuring or testing
Reexamination Certificate
1999-04-23
2001-10-02
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Including measuring or testing
C435S288700, C435S309100, C382S133000, C600S569000
Reexamination Certificate
active
06297044
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a minimally invasive apparatus and method for testing lesions of the oral cavity and similar epithelium.
BACKGROUND OF THE INVENTION
Between 5% to 10% of patients in general dental and medical practice have harmless appearing oral lesions which are routinely noticed on oral examination, or which are incidentally observed while performing a cosmetic or other dental procedure. Visual inspection and palpation of these lesions to detect early stage oral cancer is highly unreliable. This is because benign, dysplastic and cancerous lesions are often indistinguishable from each other on clinical inspection. The vast majority of these relatively benign appearing lesions are, in fact, benign. However, at least 6% of these benign appearing lesions may be pre-cancerous or cancerous, and failure to identify these dangerous lesions at an early, treatable stage, is a primary factor in the currently low five-year survival rate for oral cancer.
The dentist or physician who visually detects an oral lesion which is not clearly suggestive of precancer or cancer is faced with a quandary when restricted to the methods and apparatus of the prior art. The only accurate tool currently believed to be available in the prior art to distinguish benign from pre-cancerous and cancerous oral lesions is a lacerational or scalpel biopsy of the lesion followed by histological examination of the excised tissue. In a scalpel biopsy, a variety of surgical cutting instruments are used to obtain a tissue sample. If such a scalpel biopsy removes a part of the lesion it is referred to as an “incisional” biopsy, while if it removes the entire lesion it is referred to as an “excisional” biopsy.
In either case, a scalpel biopsy is a painful, lacerational, highly invasive procedure. Typical instruments for this purpose include, but are not limited to a flat scalpel blade, a round scalpel blade (punch biopsy) and scissors. Local anesthesia is always required. Considerable bleeding from the wound is common and suturing is often necessary. For these reasons, primary care dentists and physicians, those clinicians who most often encounter benign appearing oral lesions, are reluctant to perform a scalpel biopsy. When necessary, these clinicians will therefore generally refer the patient to an oral surgeon or oral pathologist for the procedure. Since as many as 5% to 10% of all patients in a typical dental or general adult medical practice may have such visible oral lesions, many of which are likely to be benign, performing a scalpel oral biopsy in the primary care setting or referral to a specialist for such performance is reserved for only the most clinically suggestive lesions. Yet, as has repeatedly been shown, pre-cancerous and cancerous oral lesions often mimic benign lesions. Lacking the subject invention, these precancerous or cancerous, but benign appearing, oral lesions typically do not receive any immediate diagnostic evaluation and are thus allowed to progress to an advanced stage of oral cancer. Once such progression is underway and continues untreated, the patient's chances for recovery diminishes.
A prior art approach which has attempted to address this problem in testing lesions of the oral cavity was the use of cytology. In this approach, a sample of cells which was naturally exfoliated from the surface of a lesion into mucous or saliva is examined microscopically. While cytology is commonly used to detect precancer and cancer in other body sites, it has not proven to be useful in the oral cavity because of its low sensitivity, i.e. its high false negative rate. It is believed that this high false negative rate is in part due to the fact that many oral lesions have an overlying keratin layer which limits availability to the lesion surface of naturally exfoliated abnormal cells. In one large study, oral cytology was found to have a false negative rate of 30%. This means that 30% of oral lesions determined to, in fact, be precancerous or cancerous on scalpel biopsy and histology were falsely reported as “negative” using oral cytology. Due to its unreliable sensitivity, prior art cytologic technique is rarely used to test oral lesions or similar keratinized epithelial lesions for precancer or cancer.
SUMMARY OF THE INVENTION
In accordance with the invention, a cytological or cellular sample of an oral lesion is taken from a patient for analysis. In one embodiment, this sample is obtained by means of a non-scalpel instrument which is sufficiently abrasive to penetrate all three layers (basal, intermediate, and superficial) of the oral epithelium. In the preferred embodiment, this trans-epithelial sample is obtained by means of pressing and rotating a circular stiff nylon brush several times over the entire lesion surface. Alternatively, the sample can be obtained using cytology or histology, and can be any cellular specimen, including cells sloughed off naturally, or cells removed by a health care professional, including a tissue specimen or oral biopsy.
As an alternative or additional feature of the subject invention, a cellular sample (preferably trans-epithelial) is examined with the aid of an image recognition system designed to identify minimal evidence of pre-cancerous and cancerous change. In accordance with the invention, the system can detect small numbers of abnormal cells distributed among the large number of normal cells obtained during the sampling procedure.
In this alternate or additional embodiment, the subject invention preferably overcomes the limitations and difficulties associated with analysis of cellular specimens for abnormal characteristics by providing an image recognition system which detects characteristics relating to abnormal keratinization of the cells. Preferably, these characteristics include color saturation associated with such abnormal keratinization.
In the preferred embodiment, the subject invention overcomes the sensitivity limitations of prior art oral cytologic technique by combining both innovations in oral pathology, namely: 1) a non-scalpel cellular sample of all three layers of the oral epithelium; and 2) subjecting this novel sample to inspection by the novel image recognition system specifically designed to detect minimal evidence of early precancerous change in a trans-epithelial sample from an oral lesion, or other lesion with similar epithelia. This novel image recognition system preferably analyzes for the presence of abnormal keratinization, by detecting predetermined characteristics of color saturation.
For purposes of this patent application, the prior art scalpel procedure is defined as lacerational, whereas the novel invention herein is non-lacerational and therefore minimally invasive. To the extent that an abrasive brush has characteristics that may cause minor discomfort and/or bleeding, there is substantial difference between the prior art scalpel trauma and the minimal trauma associated with the present invention.
Thus, in the preferred embodiment of the invention, the image processing system combines: 1) sensitivity to the presence of abnormal cellular morphology obtained from any or all of the three layers of the novel trans-epithelial cellular sample with 2) sensitivity to the presence of abnormally keratinized cells as are commonly found in any or all of the three layers of the epithelia, and also obtained by means of the novel trans-epithelial cellular sample of the subject invention. Thus, the keratin component, which presented an obstacle to prior art oral cytology, is both penetrated, to ensure that any underlying abnormal basal cell morphology is available for analysis, and productively utilized, as a means of increasing the method's overall sensitivity to evidence of precancerous and cancerous change.
In a preferred embodiment, the image recognition system selects the most suspect abnormal cells and cell clusters among the sample, and displays these cells and cell clusters on a video monitor for expert review.
In the preferred embodiment, the image recognition system also prov
Eisen Drore
Frist Stephen
Recht Joel
Beisner William H.
Levisohn, Lerner, Berger & Langsam
Oralscan Laboratories, Inc.
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