Lichen planus is a common chronic inflammatory mucocutaneous disease and 50% of cases often haveoral mucosa.The etiopathogenesis of oral lichen planus (OLP) has yetbeen poorly understood, but T cell-mediated immunity and inflammatory pathways play a partin its pathogenesis [1]. Many studies refer to autoimmune properties of OLP such as chronicity of the disease, prevalence in adulthood, an inclination to the females. involvement with other autoimmune diseases , an increase in immunosuppressive activity in patients with OLP, and the presence of auto-toxicity cells in OL lesions support the autoimmunity role of disease pathogenesis [2].Considering that squamous cell carcinomas (SCC) have been developed from LP, several studies have focused on malignant transformation of OLP lesions to oral SCC (OSCC), as it has become a concerning global topic . Based on the definition of WHO, the term “oral lichen planus” is known as aPotentially Premaignant condition. The molecular mechanisms underlying the development of oral cancer are not clearly known in patients with OLP, but OLP lesions can evolve from normal epithelium or precancerous lesions and the disruption of basement membrane may trigger the Keratinocyte (KC) apoptosis [3].
OSCCis the most common neoplasia of the oral cavity and a serious worldwide health problem; thus, understanding the SCC biomarkers is essential for early diagnosis,better prognosis and the prevention of disease recurrence and a good way to decrease the mortality of patients. Malignant transformation of oral mucosa causes the proliferation of cells, abnormal keratinization, epithelial dysplasia, increased cell motility, and angiogenesisdue to gene mutation in cell growth and its regulation. Cancer occurs throughgenetic changes that cause deregulation of protein, poor cell division, and tissue differentiation, invasion, and metastasis [4].
Tumor indicators have recently been recognizedfor theearly diagnosis of malignancy. In oral cavity carcinomas, different serum indicatorsincluding oncofetal proteins (alpha photoprotein CEA), B proteins and enzymes (LDH)have been studied. One of the most significant indicators is β2microglobulin,a protein with light(low weight) molecules(11800 kDa).It is found on each surface ofcellexcept for erythrocytes which are considered as a light unchangeable chain of compatible histologic antigens [5]. It is abundant in monocytes and lymphocytes[6]. In the normal physiologic state, some amounts of β2microglobulin can be secreted to the cell or serum due to the intracellular release and it is often extracted from the blood by kidneys[7-11]. Thus, β2 concentration of microglobulin (β2M) is measuredby the amount ofproduction and secretion to serum and extraction by kidneys [12]. β2M concentration increases as a result of the kidney's dysfunction and cells' turnover [13]. Thus, in individuals with healthy kidneys , an increase in the β2M amount indicates the proliferationof the changed cells. Increasing β2M amount in serum was observedin some pathologic cases including kidney diseases, immunity deficiency, and autoimmune disease. Besides, there was a high level of β2M in some solid and hematologic cancers in the time of diagnosis [14, 15]. Saliva-based analysis has been proposed in recent years and the potentially abnormal markers of oral cavity appear in saliva directly or indirectly. Therefore, its application as a diagnostic fluid can be of special significance. Saliva is a diagnostic tool forassessing markers. It is advantageous because it is cheap for monitoring, safe for collecting, non-invasive, convenient, simple and reproducible, ;without causing discomfort tothe patient[16-18].
Baliah etal., (2017) determined the β2M level in serum in patients with oral leukoplakia, oral submucous fibrosis and oral squamous cell carcinoma; andcompared to the control group. A total of 100 caseswere classified in fourgroups: the first group contained patients with oral leukoplakiabased on the clinical and histopathological reports; the second group consists of patients with oral submucous fibrosis; the third group includes patients with oral squamous cell carcinoma (OSCC) and the last onewas the control group. Results have indicated that the mean levelof β2M in the serum of the leukoplakia, oral submucous fibrosis, OSCC patients and in the control group was2597±148.6, 2187.68±678.6, 3166.04±357.7, and 1542.60±377.70ng/mL, respectively. There was a significant increase in the meanlevel of β2M concentration in the first and the third groupscompared to the control group. However, anincrease in β2M concentration in patients with oral submucous fibrosis was not statistically significant. The presentstudyhas supported the hypothesis of using β2M concentration as an indicator in patients with oral leukoplakia and oral squamous cell carcinoma [19].
Diwan et al., (2016) studied the role of β2M as a tumor indicator in OSCC and leukoplakiapatients. For this purpose, OSCC patients(n=30), leukoplakia patients (n=23), and normal individuals (n=20) in the control group were analyzed. Using the logistic regression model, the effect of age and gender was removed from samples dueto their influence on β2M concentration. Results showed that β2M concentration was higher in OSCC and leukoplakia patients compared to the control group. Thus, β2microglobulin in serum can be used as an indicator in the diagnosis of these diseases. Increasing theconcentration of β2microglobulinwas positively correlated with grading the histology of OSCC[18].
The study of Gonazales et al aimed to assess the evidence on the ability to transform to malignant OLR, OLL, and different variables with the highest effect on the development of disease weredetermined [20] . They investigated 82 studies on a total of 26742 patients by November 2018. The malignancy speed was reportedOLR:1.72, OLL:1.88, OLP:1.14 . The analysis of subgroups showed that the ability to be transformed into malignancy depends on variables such as Epithelial dysplasia, the location of the lesion, smoking, consuming alcohol, type of lichen planus and accompanying lichen planus with hepatitis C.Giuliani et al confirmed that OLP,OLL may be considered a potentially malignant disorder [21]. The type of erosion, femaleness, and location of the lesion were considered as risk factors. Accurate clinical criteria and histology are essential for the diagnosis of oral lichen planus.
Thus, considering the high prevalence of oral cancers and oral lichen planus in Zahedan, the lack of similar study, and proving the safety and usefulness ofsaliva as a diagnostic method of oral cancer and Lichen planus, we have analyzed the β2M concentration in these patients.