The present prospective study was conducted in the Department of Oral Medicine and Radiology, after obtaining the approval from the Institutional Ethics Committee (IEC) of Sumandeep Vidyapeeth, bearing number SVIEC/ON/DENT/RP/1520 dtd. 04/12/2014 and SVIEC/ON/DENT/RP/15034 dtd. 29/06/2015.

The total of 250 participants, equally divided into five study groups – OSMF, OL, NS, OM and age and sex matched HC, which were diagnosed clinically and histopathologically and were classified accordingly [3,11,12] depending on the severity; formed the part of the study [Table/Fig-1,2]. Participants who had undergone treatment for the lesions and having systemic disease (like scleroderma, anemia etc.,) were excluded from the study.

[Table/Fig-1]:

(a) Shows blanching and presence of fibrous bands in right buccal mucosa; (b) Shows blanching of soft palate; (c) Shows homogenous oral leukoplakia on right buccal mucosa; (d) Shows non-homogenous oral leukoplakia on right commissure and buccal mucosa.

[Table/Fig-2]:

(a) shows grayish black pigmentation on palatal mucosa with inflamed openings of minor salivary glands; (b) Shows erythematous palatal mucosa; (c) Shows deep burrowing ulceration in lower left gingival; (d) Shows proliferative lesion in lower canine premolar region. The black arrow denotes the extent of the lesion towards the buccal mucosa.

After obtaining informed consent, 5 ml of blood was aspirated from right/left antecubital vein, which was centrifuged at 2000 rpm for 10 minutes to separate the serum. The serum was then analyzed for total proteins and albumin levels using diagnostic kit-Liquixx Total Protein Erba Mannheim and Liquixx Albumin Erba Mannheim respectively, and EBRA EM 200 fully automatic analyzer. The serum globulin levels were obtained by subtracting the values of total proteins and albumin. The statistical analysis was performed using SPSS version 19.0 and tests applied were one-way ANOVA and Tukey’s Post-Hoc analysis for multiple comparisons.

The participant’s age ranged from 18 to 82 years, with a mean age of 46.32±13.89. There were total 193 males and 57 females with the M:F ratio of 3.4:1 [Table/Fig-3].

The serum protein levels were estimated in all the groups and the statistical difference was analyzed by using one-way ANOVA test. The mean value of total protein was minimum (5.012±1.493) g/dl in NS group and was maximum (6.212±1.618) in OM group; which was statistically significant (p<0.001). The mean value of albumin was minimum (3.389±0.911) g/dl in NS group and maximum (3.762±0.716) g/dl in OSMF group; which was statistically not significant (p>0.05). Similarly, the mean value of globulin was minimum (1.623±0.844) g/dl in NS group and maximum (2.675±1.145) g/di in OM group; which was statistically significant (p<0.001) [Table/Fig-4].

The correlation of total protein levels between each study group was performed by Tukey’s Post-Hoc analysis. The difference was statistically significant (p<0.05) between OL and OM group, and NS and HC group; whereas statistically highly significant (p<0.001) difference was noted between NS and OM group [Table/Fig-5].

The correlation of albumin level between each study group was performed by Tukey’s Post-Hoc analysis and was statistically not significant (p>0.05) [Table/Fig-6].

The correlation of globulin levels between each study group was performed by Tukey’s Post-Hoc analysis. The difference was statistically significant between OL and OM groups (p<0.05); whereas statistically highly significant difference was noticed between OSMF and OM, OSMF and HC groups, NS and OM, NS and HC groups (p<0.001) [Table/Fig-7].

The term free radical is generally used to describe a molecular fragment containing one or more unpaired electron in its valance shell and is capable of existing independently. Free radicals in high concentrations interact with intracellular macromolecules such as DNA, proteins, carbohydrate and lipid thereby, initiating and promoting inflammation and carcinogenesis [13]. Oxidation of protein plays an important role in pathogenesis of cancer and studies have demonstrated decreased protein levels in cases of OPMD’s and oral malignancy [8,9]. In oral cancer, tobacco and areca nut related habit leading to tissue damage and resultant free radicals play a major role as an aetiologic factor. These habits are seen commonly in all the ages and both the sex.

The serum protein levels were decreased in OSMF, OL and NS but increased in OM. This difference was statistically significant (p<0.001). These findings matched with the findings of Patidar KA et al., and Rajendran R et al., in OSMF participants and Dawood RM et al., in OM participants [5,6,14]. But our results did not simulate with the results of Chandran V et al., in OM group in which the plasma protein levels were found to be decreased [8]. The increase in serum protein levels may be explained in terms of inflammatory reaction associated with oral malignancy.

The intergroup comparison of serum albumin was statistically not significant (p> 0.05) and this was not in accordance with the studies of Rajendran R et al., Chandran V et al., Nayyar AS et al., and Singh P et al., [6,8–10]. The intergroup comparison of serum globulin levels was statistically highly significant (p<0.001). The serum globulin levels were decreased in OSMF, OL and NS but increased in OM. This finding was similar to that of Dawood RM et al., [14]. The increase in serum globulin levels may be due to its action as an acute phase reactant.

The Limitation of the study is that epithelial dysplasia and correlation is not included in the present study.

The present study demonstrated decrease in serum protein, albumin and globulin levels in OSMF, OL and NS but increase serum levels of proteins in OM. It may be concluded that serum protein may act as a reliable biomarker for OPMD’s and OM.