What Are the Diagnostic Standards for Oral Cancer Detection?
Early-stage oral cancer lesions may be often asymptomatic and may mimic other systemic conditions. The advanced stages of cancer develop over a long period of time. This is because the cells undergo multiple stages of abnormal biologic differentiation and later proliferation. Hence the ideal stage of treatment at this early or pre-invasive stage offers the best prognosis and the chance of a cure for oral cancers.
A biopsy is the diagnostic gold standard recommended by dentists for detecting oral premalignant and malignant lesions. However, with the use of scalpel biopsy (which is an invasive procedure) associated with potential morbidity, several adjunctive aids have gained popularity now.
What Is the Scope of Exfoliative Cytology?
Exfoliative cytology is the preferred technique of analysis in dentistry which is an improved version of biopsy, non-invasive, rapid, simple, easy to collect, and cost-effective method. It is advantageous, especially in developing countries and in resource challenges areas.
Exfoliative cytology is used to assess both normally appearing oral mucosa of usual epithelial changes associated with mild lesions to clinically and biologically diagnosable conditions like leukoplakia, oral squamous cell carcinoma, or premalignant lesions, and red and white lesions of the oral cavity.
Exfoliative cytology is basically the microscopic examination of desquamated or isolated cells from the surface of a lesion. It is performed to mainly visualize microbiological changes and for measurement of hormonal levels. The cells may be obtained by any of these procedures like aspiration of washing of cells or by obtaining a smear or by scraping. The technique can also be employed to obtain and study the secretions of sputum, urine, abdominal fluid, prostatic secretions, and vaginal fluid discharge.
Is Exfoliative Cytology an Ideal Diagnostic Technique?
The diagnosis of oral lesions depends mainly upon the criteria of cell atypia, including cellular keratinization and morphological deviations.
Ideally, a diagnostic procedure should be neither time-consuming nor complicated. The high specificity of this diagnostic technique always relies upon the capacity of specificity of the technique to avoid false-positive results. Exfoliative oral cytology has many benefits, including alleviating patient anxiety and fears, avoiding additional investigations and even unnecessary treatment modalities.
The basic requirement fulfilled by a useful diagnostic technique like exfoliative cytology is that it is:
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Easy to use.
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Causes minimal patient discomfort.
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Collects sufficient cells from the area to be analyzed.
What Are the Different Types of Cytology?
1) Traditional Exfoliative Cytology:
The traditional methods of exfoliative cytology are no longer used for investigation in recent decades, especially because of poor sensitivity and technique specificity for identifying dysplasias and malignancies or cancers. During the 1980s, the introduction of cytobrush was the first innovative methodology for cervical smears (gynecologic purposes). The use of the cytobrush eventually for diagnosing oral cancer revived, thus a major interest in oral cytology procedures. Since then, various researchers have described different diagnostic techniques that have improved the sensitivity and specificity of conventional oral cytology.
2) Oral Brush Biopsy for Cancer Detection:
Similarly, the oral brush biopsy with computer-assisted analysis is another procedure simple enough to perform and non-invasive. OralCDx is one of the computer-assisted methods for cellular sample analysis collected by using a patented brush. The technique is mainly designed to evaluate any kind of epithelial abnormalities, and not just for the detection of cancer or dysplasia-related etiology. In this technique, the computer analyzes the digital microscopic image of the collected cells obtained after scanning. It uses a specialized form of neural network-based image processing particularly designed to detect oral lesions. In the detection of both precancerous and cancerous cells, oral brush biopsy is recommended by most oral and maxillofacial surgeons.
3) Liquid Cytology:
The use of liquid-based cytology offers improved smears or preparations rather than conventional cytology. This reduces the false-negative results compared to traditional cytology procedures. Issues pertaining to either sampling or fixation can be addressed in this manner that presents a better cytological cell understanding and outline. The advantage of this liquid-based cytology is that the pathologist can prepare one or more than one slide per sample collected. In this, there remains enough material for other techniques besides the commonly used Pap stain, periodic acid-Schiff (PAS), methenamine silver stain, etc. Finally, the material preserved in the solution has a long shelf life allowing for additional investigations if needed, like immunostaining.
4) Oral Rinse Cytology:
The oral rinse technique has been the earliest cytologic use for microbiological investigation and analysis of oral candidiasis and to study oral candidal colonization. In recent decades, this technique has been increasingly popular to detect oral cancers or oral squamous cell carcinomas. The technique relies upon the logic of "aberrant methylation" or rather a combination of marker genes present in the oral rinse samples. These genes have high sensitivity and specificity for potential detection of oral cancers especially.
The recent potential of this technique is to detect non-invasively oral squamous cell carcinomas (OSCC). It has been useful in dental research about cancer cell morphology and genetics. Hence the advantages include distinctive cell morphology and visual clarity. The oral rinse-based preparation can thus be considered as an alternative technique to conventional smears. This can also be used whenever a surgical biopsy is not possible (such as in rural areas) in the absence of trained healthcare workers or lack of armamentarium.
Conclusion:
With further advancements in this emerging field of oral exfoliative cytology, interest and scope of oral cytology have once again emerged tremendously. This necessitates the need for trained staff and armamentarium in a clinical setting for sample collection.
