The Implication of the Preoperative Neutrophil to Lymphocyte Ratio in the Diagnosis of Laryngeal Squamous Cell Carcinoma: A Retrospective Analysis

Aims: There is growing evidence that the neutrophil to lymphocyte ratio (NLR) may be used as a prognostic factor in many head and neck cancer types. We aimed to investigate the diagnostic implication of the NLR as a biological marker in predicting the malignancy of laryngeal lesions. Study Design: This is a retrospective study. Methodology: The medical records of the patients who underwent an operation for a laryngeal pathology between September 2010 and January 2015 were retrospectively reviewed. For the control group, 50 age and sex matched patients were selected among the patients who underwent septoplasty. Preoperative neutrophil to lymphocyte ratio was calculated for each subject in the malignant, benign and control groups. Results: Comparison of the three groups yielded a statistically significant difference between the groups (p<0.05, p=0.025). Comparison of the malignant group with the healthy control group showed that the median NLR was higher in the malignant group (p<0.05, p=0.011). Original Research Article Ciftci et al.; JCTI, 2(3): 144-149, 2015; Article no.JCTI.2015.015 145 Conclusions: Preoperative NLR was significantly elevated in laryngeal cancer patients in our study. We are of the opinion that, this cheap and easily accessible hematological parameter may have a potential role in predicting the malignancy of a space occupying laryngeal lesion. Further clinical studies should be conducted to clarify this association.


INTRODUCTION
Neutrophils are considered to be the first line of defense against various infections and they constitute 50-70% of all polymorphonuclear leukocytes in the human circulation [1]. Despite their well-established role in the host defense system against microorganisms, relatively little is known regarding the functions of neutrophils in cancers involving humans [2]. There appears to be an increased level of circulating neutrophils in patients with advanced stage cancers probably due to secretion of certain cytokines by the tumor tissue. These cytokines, among others, GM-CSF, G-CSF, IL-1, IL-6 and vascular endothelial growth factor were found to be responsible for the presence of neutrophilia in the bloodstream [3][4][5]. However, neutrophils were proposed to demonstrate conflicting functions in cancer and reported to have both anti-tumor and pro-tumor subpopulations. Neutrophils infiltrating the tumor were found to release various mediators that increase, rather than decrease, tumor angiogenesis and malignant cell intravasation [1,6,7]. Furthermore, it was pointed out that neutrophils from head and neck squamous cell carcinoma patients were different from their counterparts in the healthy subjects both in terms of functionality and cell counts [8,9].
There is growing evidence that the neutrophil to lymphocyte ratio (NLR), a routinely available biological marker of systemic inflammation, may be used as a prognostic factor in many head and neck cancer types. Increased NLR was shown to be an indicator of poor prognosis in oropharyngeal carcinoma, nasopharyngeal carcinoma, and thyroid carcinoma patients [8,10,11]. Elevated NLR was also proposed to be a useful inflammatory marker to differentiate lung cancer patients from healthy control patients in a recent study [12]. Literature review revealed that, there are only a few studies regarding the role of NLR as either a predictive marker for prognosis or a diagnosis of malignancy in patients with a laryngeal pathology. To the best of our knowledge, only in one study, NLRs of the patients with pre-cancerous and malignant lesions were compared with NLRs of the patients with benign laryngeal lesions and NLRs of the former group were found to be significantly higher [13]. Therefore, in this study, we aimed to investigate the diagnostic implication of NLR as a biological marker in predicting the malignancy of laryngeal lesions.

METHODOLOGY
The medical records of the patients who underwent an operation for a laryngeal pathology between September 2010 and January 2015 in a tertiary referral center were retrospectively reviewed. Patients who had a complete blood count analysis done before the laryngeal biopsy procedure were enrolled into the study. The patients were allocated into two groups according to their definitive pathology report, either benign or malignant. Patients with a history of diabetes mellitus, chronic hypertension, chronic obstructive pulmonary disease and other chronic inflammatory conditions were also excluded. For the control group, 50 age and sex matched patients were selected among the patients who underwent septoplasty within the same period of time. Preoperative white blood cell, neutrophil and lymphocyte counts were investigated and neutrophil to lymphocyte ratio was calculated for each subject.
Statistical Package for Social Sciences (SPSS) for Windows version 17 (Illinois, Chicago) was used for statistical analysis. Variables were tested for normality using Kolmogorov-Smirnov test. The descriptive data were presented as median (minimum-maximum). For the comparison of the quantitative data that did not display a normal distribution among 3 groups, Kruskal Wallis test was used. For 2 group comparisons, Mann Whitney U test was used. In all tests, p <0.05 was accepted to be statistically significant.

RESULTS
Between September 2010 and January 2015 a total of 118 patients were found to be operated for a laryngeal pathology. 21 patients were excluded from the study due to their co-existing chronic inflammatory conditions. A total of 97 patients were investigated. The patients were divided into two groups according to their histopathologic diagnosis. 53 patients were found to have laryngeal squamous cell carcinoma and 44 patients were found to have a benign laryngeal lesion (e.g. laryngeal nodule or polyp). The NLRs of the patients in malignant, benign and control groups were calculated. Comparison of the three groups using Kruskal Wallis test yielded a statistically significant difference among the groups (p<0.05, p=0.025) ( Table 1).
Comparison of the malignant group with the healthy control group showed that the median NLR was higher in the malignant group. The difference was statistically significant (p< p=0.011). Comparison of the malignant group with the benign group showed that the median NLR was also higher in the former group. This

DISCUSSION
In this study, we aimed to assess the NLRs of the patients with benign or malignant laryngeal lesions and compare them with the NLRs of the healthy control subjects. Our results revealed a statistically significant difference among these three groups. The median NLR was lower in healthy controls than the other groups. The difference between the healthy group and the malignant group was statistically significant. These findings were consistent with the previous difference, however, did not have a statistical significance (p<0.05, p=0.314). The median NLR er in the benign group in comparison to the control group but this difference was not statistically significant In this study, we aimed to assess the NLRs of ignant laryngeal lesions and compare them with the NLRs of the healthy control subjects. Our results revealed a statistically significant difference among these three groups. The median NLR was lower in healthy controls than the other groups. The e between the healthy group and the malignant group was statistically significant. These findings were consistent with the previous  [13,14].
The implication of the NLR as a biological marker for predicting the survival was extensively investigated in the literature for various types of cancers. The NLR was suggested to be superior to other hematological parameters in predicting the short or long term mortality in breast cancer patients. Individual parameters were proven to be altered by physical, physiological and pathological factors but the NLR was found to be relatively more stable even under the influence of such factors. It was also proposed that the NLR might represent both the inflammatory and immune pathways which are opposing in nature but exist together in cancer patients [15]. An elevated NLR was reported to be an independent factor for poor prognosis in patients with colorectal, lung, and renal cancers [16][17][18].
As far as head and neck malignancies are concerned, the NLR was also found to be increased in patients with certain tumors. A high preoperative NLR was reported to be associated with poor survival in patients with hypopharyngeal squamous cell carcinoma [19]. The NLR was also accepted to be a 'prognosticator' in patients with metastatic nasopharyngeal carcinoma [20]. The association between the NLR and disease-free survival in papillary thyroid carcinoma patients was investigated in one study and they concluded that, elevated NLR could be a negative prognostic factor for disease free survival [21]. In a previous study, Duzlu et al. attempted to identify the potential prognostic role of the NLR in patients with laryngeal cancer and they found that the NLR was increased especially in the presence of regional lymph node metastasis and advanced stage disease [22].
Besides its prognostic role in various cancers, the role of the NLR in the diagnosis of many clinical conditions was also extensively studied in the literature [23,24]. In addition, the implication of the elevated NLR in the diagnosis of malignancy was also investigated by researchers. Elevated NLR was proposed to be a useful marker in diagnosis lung cancer [12]. Literature review revealed that, the diagnostic role of the NLR in laryngeal carcinoma was not extensively investigated. Only in one study by Kum et al. the NLRs of patients with benign, precancerous and malignant laryngeal lesions were compared and diagnostic value of the NLR in laryngeal lesions were analyzed. It was concluded that, the NLR could be a useful inflammatory marker to differentiate laryngeal squamous cell carcinoma from benign and precancerous laryngeal lesions [13].
In the present study, the NLRs of the healthy control subjects were also investigated and compared with NLRs of the patients with either a benign or malignant laryngeal lesion. The findings indicated that the inflammation elicited by either benign or malignant lesions in the laryngeal region could be successfully reflected by increased NLR levels. NLR was increased significantly in cancer patients in comparison to healthy subjects. This increase was in concordance with the previously reported studies pointing out the role of the NLR as a reliable inflammatory or immune marker in human cancer [6,13,15].

CONCLUSION
In conclusion, preoperative NLR was significantly elevated in laryngeal cancer patients in our study. Laryngeal biopsy and imaging modalities are the gold standards in the diagnosis of squamous carcinoma of the larynx. Although it is not possible to suggest it as a substitute for these gold standards, we are of the opinion that, this cheap and easily accessible hematological parameter may have a potential and adjunctive role in the diagnosis of malignant laryngeal lesions. Further clinical studies should be conducted to clarify this association and determine a cut-off value for the NLR.

CONSENT
It is not applicable.

ETHICAL STATEMENT
All procedures performed in studies involving human participants were in accordance with the 1964 Declaration of Helsinki and the 2013 National Code on Clinical Researches. According to the National Code, for retrieving the data retrospectively, approval of the ethics committee is not necessary.

COMPETING INTERESTS
Authors have declared that no competing interests exist.