REVIEW OF SCIENTIFIC ARTICLES
|Year : 2007 | Volume
| Issue : 2 | Page : 89-91
Review of scientific articles
A Einstein, Bhushan Sharma
Department of Oral and Maxillofacial Pathology, Meenakshi Ammal Dental College and Hospital, Alapakkam Road, Maduravoyal, Chennai, India
Department of Oral and Maxillofacial Pathology, Meenakshi Ammal Dental College and Hospital, Alapakkam Road, Maduravoyal, Chennai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Einstein A, Sharma B. Review of scientific articles. J Oral Maxillofac Pathol 2007;11:89-91
Cancerisation within the oral cavity: The use of 'field mapping biopsies' in clinical management
Thomson PJ, Hamadah O
ORAL ONCOL 2007,43:20-26
This paper concentrates on the effectiveness of multiple 'field mapping biopsies' in the initial identification and treatment of the most significant area of dysplasia in patients with multi focal pre-cancer. The concept of field cancerisation is used to explain why premalignant change may occur in any area of mucous membrane exposed to carcinogens, and thus is responsible for the risk of developing multiple primary lesions in patients with oral pre cancer or cancer.
Examination under anaesthesia and multiple 'field mapping biopsies' were carried out for 16 consecutive patients presenting with pan-oral disease. Seventy oral lesions were identified in these patients. The majority of the lesions appeared clinically as homogenous leukoplakic plaques, with nodular and erythroplakic or speckled lesions being less common. Interventional CO 2 laser surgery was used to excise 11 severely dysplastic lesions in six patients. Histopathological examination revealed that the majority of lesions showed either hyperkeratosis or mild dysplasia; significant number displayed moderate dysplasia; severe dysplasia and carcinoma in situ were less common. All patients were followed up for minimum of 2 years post mapping. Neither did the patients develop an invasive squamous cell carcinoma, nor did any lesion recur during the 2-year follow-up period.
A previous study has demonstrated histopathological abnormalities in normal appearing oral mucosa in 15 out of a consecutive series of 26 patients presenting with oral cancer or precancer. Also it is not possible to predict the clinical behavior of premalignant lesions on the basis of clinical appearance or histopathological features alone. Thus oral leukoplakia, particularly when multi-focal or widespread, should be regarded as a marker for increased cancer risk throughout the upper aerodigestive tract and not just as isolated premalignant lesions. Interventional laser surgery is an efficacious, low morbidity treatment which is effective in eliminating precancers.
Recent advances in Oral Oncology
Scully C, Bagan JV
ORAL ONCOL 2007,43:107-115
This paper concentrates on the etiopathogenesis, epidemiology, prevention, clinical features, diagnosis, treatment, and management of neoplasms of the head and neck and orofacial diseases in patients with malignancies.
The role of tobacco, alcohol, and viruses in the development of oral lesions like oral submucous fibrosis and oral cancers, malignant transformation rate, and survival rate of oral lichen planus are discussed. Significant findings such as the association of P57 expression in leukoplakia and oral squamous cell carcinoma with advanced tumor size, occurrence of lymph node metastasis and p53 expression being higher in oral lichen planus than oral lichenoid lesions, non-homogenous leukoplakia having a 7-fold higher risk for malignant transformation compared to homogenous leukoplakias are presented in detail. Role of toluidine blue test in differentiating benign and malignant lesions is also discussed. An alarming fact presented is the increasing incidence of oral cancer in the younger age group and in women.
Review of literature on molecular studies has highlighted various findings: metabolizing enzymes are involved in the detoxification of many carcinogens, thereby explaining the individual variations in genetic susceptibility; high percentage of oncogen Ras mutation occurs in oral cancer; Cyclin D1, a down stream member of the Ras pathway is over expressed and is associated with poor prognosis; expression of cyclin D1 is associated with lymph node metastasis and tumor thickness; Ki - 67 and activated Extracellular signal-regulated Kinase (ERK1/2) are significantly associated with moderately or poorly differentiated grade; TGFβ and EGF affect gene expression in primary and metastatic SCC cells; and MMPs and TIMPs play important role in cancer initiation and development. Review on the management of oral cancer presents the update on different treatment modalities like radio therapy, chemotherapy, immunotherapy, and photodynamic therapy. A appreciable endnote to the paper is the stress on the fact that the patient should be provided with information about the quality of life and should be satisfied before treatment so that post operative problems like depression can be overcome.
Advances in the biology of oral cancer
Tsantoulis PK, Kastrinakis NG, Tourvas AD, Laskaris G, Gorghoulis VG
ORAL ONCOL 2007,43:523-534
This paper reviews the current literature pertaining to the advances in the field of cancer biology. The familial risk for oral cancer could be acquired as a result of imitating high risk habits within the family such as smoking and drinking or as a genetic trait. Single nucleotide polymorphism A/G 870 in the CCN1 gene that encodes cyclin D has been associated with oral cancer susceptibility.
The aggregation of genomic alteration during phenotyping progression is assumed to happen in a wide population of cells, a heterogeneous field of genetically altered cells that is expected to give rise to precursor lesion. This is called 'field cancerisation'. The exact molecular characteristics of a susceptible genetically altered field are not clearly defined, but key tumor suppressor such as TP53, CDKN2A and the pRb pathway are likely to be compromised from its earlier stages.
Several reports indicate the high prevalence of LOH or homozygous deletions in 3p, 9p, 13q, and 17q in early oral lesions. Aberrations associated with advanced tumor stage or poor differentiation include allelic losses in 5q21-22, 22q13, 4q, 11q, 18q and 21q. Oncogenes like gelatinases (MMP-2 and -9), stromelysin (MMP-3-10, and-11), collagenase (MMP-1 and-13) and membrane bound MMPs (MT1-MP) are expressed by malignant cells, while MMP-2 and-11 are probably produced by the stromal cells. Down regulation of p16, p14, p15, p53 and INK4 family members may be responsible for oral cancer.
Human Papilloma virus (HPV) alone is incapable of inducing malignant transformation. Instead, the tumorigenic action of high risk HPV probably becomes significant in synergy with chemical carcinogens ad other factors. LMP-1, the principal oncoprotein of Epstein - Barr virus (EBV) has been found in many EBV-positive OSCCs which means that Epstein Barr virus infection is more prevalent in patients with oral lichen planus. However 1-2%of the patients with oral lichen planus develop squamous cell carcinoma of the oral cavity, which implies the existence of a common pathogenic mechanism among them.
Intra-oral minor salivary gland tumors: A clinico-pathological study of 546 cases
Pires FR, Pringle GA, de Almeida OP, Chen S-Y
ORAL ONCOL 2007,43:463-470
This article reports the data of 546 intraoral minor salivary gland tumor, including 305 benign and 241 malignant, helping us understand their clinical and pathological aspects and consequently their proper management and prognosis.
Minor salivary gland tumors represent 9-23% of all salivary gland tumors. Pleomorphic adenoma and mucoepidermoid carcinoma are the most common benign and malignant tumors. Certain tumors such as sialedenoma papilliferum show a strong predilection for females, and certain tumors such as ductal cystadenoma show male predilection. The mean age of affected patients is slightly older in malignant tumors than in benign (62 yrs Vs 58 years). Though most tumors are subjected to excisional biopsy, adenoid cystic carcinoma and adenocarcinoma were commonly managed by incisional biopsy.
Palate is most commonly affected intraoral site for both benign and malignant tumors. About 80 % of tumors affecting upper lip are benign whereas 85% and 90% affecting mucobuccal fold and floor of mouth respectively are malignant. Some histological types show marked predilection for specific regions, such as canalicular adenoma for upper lip, ductal cystadenoma for lower lip, adenoid cystic carcinoma for the floor of mouth, and acinic cell adenocarcinoma for the buccal mucosa. Ten cases of pleomorphic adenoma consist almost exclusively of myoepithelial component and most mucoepidermoid carcinomas are of low or intermediate grade.
The relative frequency of malignant tumors has changed over the years; mucoepidermoid carcinoma shows 2/3 fold increase in this study compared to the existing literature, and adenoid cystic carcinoma shows a decrease over the years, apparently due to the emergence of polymorphous low grade adenocarcinoma. In this study, 56% of minor salivary gland tumors are benign and 44% are malignant which is in contrast to the cancer center data which shows more malignant tumors. This may be due to the referral of patients with malignant tumors to cancer centers for treatment.
The uncertainty of the surgical margin in the treatment of head and neck cancer
Upile T et al.
ORAL ONCOL 2007,43:321-326
This paper highlights the dilemma concerning recent minimally invasive endoscopic microsurgical techniques, which result in minimal surgical margin or oncological clearance and justify the risk of taking lesser margin with adjuvant therapy, by the attendant gain in reduced surgical morbidity.
The fundamental surgical goal is to remove all local malignant disease and it has long since been accepted that local control is better if the removal of the surrounding tissue is maximized, that is, 'more is better'. It may not be accurate to assume that malignancy develops in just one cell and there may be several foci of cancer, however one cell clone will become dominant and have suppressor effect on other clones. Hence malignancy may be surrounded by potentially malignant heterogeneous clones which do not exhibit histological appearance of malignancy. Thus edge of malignancy is difficult to define. Larger the primary lesion, higher is the local recurrence rate and mortality, even with surgically free margins. The surgical margins for upper aero digestive tract squamous cell carcinoma vary widely and carcinoma of the oral cavity, oro-pharynx, and hypo-pharynx require wider margin than larynx.
Errors in assigning margins can be due to either assessing false margins by the histology, or post removal changes (due to either post removal or post fixation shrinkage) or due to the effect of adjunctive therapy (radiotherapy or chemotherapy) on margins which make tumor margins more fibrotic and scarred, thus becoming more difficult to assess. Immunohistochemical techniques such as probe for p53 mutation and translation initiation factor elF4E have found positive staining in histologically negative surgical margin correlating with high recurrence rate. Margins are described as zones and not as an edge as there are invading extensions of tumor into surrounding tissue and five types of zones has been described. There are three fundamental approaches to deliver a surgical margin, the metric approach wherein the surgical margin should be at least 1 cm beyond the visible and palpable margin of the tumor; the barrier approach where resection is extended to an uninvolved barrier; and the metric/barrier hybrid approach as seen in head and neck resections.