Screening Method for Oral Cancer - Essay Example

?Arguments on the Use of Toluidine Blue Staining as a Screening Method for Oral Cancer in Dental Practice 0. Introduction The nature of cancer in general, as regards to the dynamics of neoplastic development and spread of cancerous masses, makes early detection equally important as treatment in surviving the disease. Hence, early detection of cancer should be a priority among oncologists and other health care professionals. Screening is a commonly acknowledged means of early cancer detection in many forms of cancer (Underwood, 2009). In oral cancer, however, scientific literature is divided as to the efficacy of screening methods. This paper elucidates on the arguments for and against the use of toluidine in screening for oral cancer. The use of toluidine blue in uterine and oral cancer screening was pioneered by Richart in 1962. A 1% aqueous solution of toluidine blue is painted over the target area for ten seconds followed by a rinse of 1% solution of acetic acid. The toluidine blue binds to the DNA on surface cells, causing the surface to take on a bluish hue. The amount of DNA material present may be used as an indication of suspected dysplasia or neoplasia (Richart 1962). 2.0. Arguments for toluidine screening Jones and Rankin (2008) consider toluidine blue staining as a diagnostic aid for the dental professional in the evaluation of the possible malignancy of oral lesions. The potency of staining with toluidine blue has been likened to that of brush biopsy in terms of early detection, speeding up of biopsy and subsequent diagnosis of oral cancer. Application of aqueous toluidine blue to a lesion followed by a rinsing of 1% acetic acid results in selective binding with dysplastic and malignant cells accurately. The blue stain also marks a good site to extract for biopsy. Extreme care should, however, be practiced to ensure that the dye is neither mutagenic nor carcinogenic for best results. Patton, Epstein and Kerr (2008) performed a systematic review of literature related to several adjunctive techniques used in the early detection of oral premalignant and malignant lesions or OPML, such as toluidine blue. A total of 23 articles were reviewed wherein the majority focused on the use of toluidine blue. Results of the review revealed the effectiveness of toluidine blue in diagnosing oral premalignant and malignant lesions in high-risk populations and suspected mucosal lesions. However, clinicians are advised not rely much on diagnostic adjuncts alone. A complete oral mucosal examination is recommended together with specialty referrals or tissue biopsy to correctly diagnose OPML. Epstein, Silverman, Epstein, Lonky and Bride (2008) evaluated the effects of ViziLite, a chemiluminiscent light source in conjunction with toluidine blue in the process of verifying lesions identified by oral soft tissue examinations. Lesion assessment by chemiluminiscense combined with toluidine blue staining was compared with conventional visual examination. Subsequently, the suspected lesions were subjected to biopsy and diagnosed through conventional histopathological methods. Moreover, toluidine staining was performed on lesions related to severe dysplasia, carcinoma in situ, and squamous cell carcinoma. Results of the assessment show an improvement in the brightness and sharpness of margin in 60 out of 97 identified lesions that underwent the chemiluminiscent exam. Meanwhile, toluidine staining exhibited a false positive rate of 55.26% while maintaining a 100% negative predictive value (Epstein, Silverman, Epstein, Lonky and Bride 2008). Fedele (2009) described toluidine blue as an indispensable tool in identifying the area damaged by a malignant lesion due to its ability to stain nucleic acids. This effect makes it easier to remove malignant lesions since toluidin blue clearly marks the boundaries of the lesion, thus allowing precise excision. Recent studies on the use of toluidine blue were rather limited due to the dearth of research efforts in relation to randomized controlled trials, histological diagnosis standards, and methods of application. Toluidine blue has exhibited good detection rates for carcinomas. However, it was observed that its success in detecting dysplasia is considerably lower. Additional drawbacks include a high incidence of false positive stains, inconsistent interpretation of mucosal stains and unclear standards of interpreting positive results (Fedele 2009). 3.0 Arguments against toluidine screening Smith, Duffy and Brawley (2010) argued that despite a growing number of novel methods of detecting oral cancer such as toluidine blue, none has shown a significant level of reliability that is comparable or superior to conventional oral examination. Moreover, toluidine blue is identified as a mutagenic substance, raising doubts on its potential as part of a general screening test. Therefore, it was suggested that a biopsy is recommended regardless of the results of the toluidine blue staining (Cawson and Odell 2008). Lingen, Kalmar, Karrison and Speight (2008) reviewed relevant literature covering present oral cancer screening, case-finding aids, and adjuncts to identify which of these components of oral cancer diagnosis exhibit properties that is comparable or superior to conventional oral examination methods. One primary oral screening adjunct, toluidine blue or tolonium chloride, has been used by surgeons to visualize the extent of an oral lesion. Despite being recommended as an oral cancer screening adjunct for several years, research on toluidine blue has been limited to studies conducted by specialists on high risk populations in secondary care settings. Studies performed under primary care settings and randomized controlled trials are yet to be seen. Current studies reveal detection levels with significantly high sensitivity. However, specifity was considered low due to a high percentage of false positive cases (Lingen, Kalmar, Karrison and Speight 2008). Martin, Kerawala and Reed (1998) acknowledged the tendency of existing clinical investigations on toluidine blue screening to use abnormal mucosa or tissue. To determine the true sensitivity of toluidine blue an experiment was conducted involving staining of both normal and abnormal tissue samples and comparing the false negative rates of both groups. Results of the experiment show the false negative rates of carcinoma-in-situ (42%) and mild-to moderate dysplasia (58%), suggesting that toluidine staining should be performed only to high-risk and more reliable methods should be utilized in most cases to avoid incorrect diagnosis. Allen (1998), and Ephros and Mashberg (1998) supported the study conducted by Martin, Kerawela and Reed (1998) indicating that based on personal and peer experiences, the benefits offered by toluidine staining to clinicians should be scrutinized due to the fact that the high degree of false-negative results may cloud clinical judgment. Overall, a suitable substitute for the widely accepted practice of oral mucosa examination is yet to materialize. Wysocki (1998) warned of the potential dangers of using toluidine blue in oral cancer screening, indicating that the mutagenic potential of toluidine blue was somehow overlooked. Aside from being capable of binding to DNA, toluidine blue also possesses photoactive properties, which damage DNA when the stained cells are exposed to light. This effect has been utilized by researchers in attempts to treat herpes simplex infections, dubbing the procedure photodynamic inactivation. However, further studies revealed that photodynamically inactivated viruses may induce neoplastic transformations in vitro and oncogenic effects in vivo, posing a potential serious health risk to patients. In addition, toluidine blue is normally disposed through sewage after the mouth is rinsed, raising concern over the potential effect it may have once it binds to viruses and bacteria found in bodies of water where sewage flows into. It is suggested that oncogenically transformed microorganisms are part of the food chain and might affect fish and aquatic life. The author concluded that the risks involved in the use of toluidine blue may far outweigh the benefits (Wysocki 1998). 4.0 Neutral arguments on toluidine screening Brocklehurst, Kujan, Glenny, Oliver, Thakker, Sloan, Ogden and Shepherd (2006) assessed the effectiveness of current oral cancer screening methods in decreasing mortality rates by conducting an electronic database search on related literature pertaining to randomized controlled trials for oral cancer screening through visual examination, toluidine blue, fluorescence imaging and brush biopsy. Out of 112 studies reviewed, only one randomized controlled trial met the inclusion criteria wherein validity assessment, data extraction, and statistical evaluation were performed by two independent review authors. The results of the lone study available revealed no significant difference in oral cancer mortality rates between screened respondents and the control group. In addition, a 34% decrease in mortality rate was observed in high-risk participants between the intervention cohort and the control arm. Despite these results, the study was unable to provide any information regarding costs, quality of life, or cases of false-positive and false-negative results. It was concluded that since the authors were only able to identify one study as a source of data, there was definitely no way to determine the effectiveness of visual examination, toluidine blue, florescence imaging or brush biopsy methods in oral cancer screening. In addition no evidence was presented regarding any beneficial or harmful effects these methods may cause. Given the foregoing arguments, the following facts can be gleaned: (1) toluidine blue can be utilized as an adjunct in oral cancer screening; (2) some studies show a high false negative rate which may lead to incorrect diagnosis if more reliable screening methods are not utilized; (3) an existing dearth of research should be addressed, particularly in relation to randomized controlled trials, mixed methods, primary care settings, and selection of samples; and (4) potential health and environmental risks posed by toluidine blue must be investigated to justify its use. The use of toluidine blue in cancer screening has undoubtedly opened new opportunities for cancer diagnosis research. However, its continued use should be backed by more relevant studies to further establish its status as a cancer screening adjunct and gain approval from government regulatory agencies such as the Food and Drug Administration. References Allen, CM 1998, ‘Editorial’, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, vol. 85, no.4. Brocklehurst, P, Kujan, O, Glenny, AM, Oliver, R, Sloan, P, Ogden, G & Shepherd, S 2006, ‘Screening programmes for the early detection and prevention of oral cancer’, Cochrane Database of Systematic Reviews, no. 11. Cawson, RA & Odell, EW 2008, Cawson’s essentials of oral pathology and oral medicine, Churchill Livingstone, Philadelphia, PA. Ephros, H & Mashberg, A 1998, ‘Letters to the editor’, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, vol. 85, no.4, Epstein, JB, Silverman, SS, Epstein, JD, Lonky, SA, and Bride, MA 2008, ‘Analysis of oral lesion biopsies identified and evaluated by visual examination, chemiluminescence and toluidine blue’, Oral Oncology, vol. 44, no. 6, pp. 538-544. Fedele, S 2009, ‘Diagnostic aids in the screening of oral cancer’, Head and Neck Oncology, vol. 1, no. 1, pp. 1-6. Jones, DL & Rankin KV 2008, ‘Oral cancer and associated risk factors’, in DP Cappelli & CC Mobley (eds), Prevention in clinical oral health care, Mosby / Elsevier, St. Louis, MO, 68-77. Lingen, MW, Kalmar, JR, Karrison, T & Speight, PM 2008, ‘Critical evaluation of diagnostic aids for the detection of oral cancer’, Oral Oncology, vol. 44, no. 1, pp. 10-22. Martin, IC, Kerawala, CJ & Reed 1998, ‘The application of toluidine blue as a diagnostic adjunct in the detection of epithelial dysplasia’, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, vol. 85, no.4, pp. 444-446. Patton, LL, Epstein, JB & Kerr, AR 2008, ‘Adjunctive techniques for oral cancer examination and lesion diagnosis’, Journal of the American Dental Association, vol. 139, no. 7, pp. 896-905. Richart, RM 1962, ‘A clinical staining test for the in vivo delineation of dysplasia and carcinoma-in-situ’, American Journal of Obstetric Gynecology, vol. 86, pp. 703-712. Smith, RA, Duffy, SW and Brawley,OW 2010, ‘Cancer screening and early detection’, in WK Hong, RC Bast Jr., WN Hait, DW Kufe, RE Pollock, RR Weichselbaum, JF Holland & E Frei III (eds), Holland Frei cancer medicine, 8th edn, People’s Medical Publishing House, Shelton, CT, 419-445. Underwood, JCE 2009, ‘Carcinogenesis & neoplasia’, in JCE Underwood & SS Cross (eds), General & systematic pathology, 5th edn, Churchill Livingstone / Elsevier, Philadelphia, PA, 221-259. Wysocki, GP 1998, ‘To the editor’, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, vol. 85, no.4. Read More