Laryngeal cancer ranks second in incidence and mortality of head and neck cancer, accounting for 1% of systemic malignant tumors, and the main pathological type is squamous cell carcinoma (96%-98%)[6]. 2020 epidemiological data in China show that the incidence of laryngeal cancer is 1.84 /100000 and mortality rate is 1.0 /100000, ranking 21st in both tumor incidence and mortality[7].
Vocal cord leukoplakia is a lamellar keratotic hyperplastic lesion on the mucosal surface of the vocal cords. The main pathological changes are mucosal epithelial hyperplasia with incomplete keratinization and mild hyperplasia of submucosal tissue[8]. Vocal cord leukoplakia manifests as white spots or patchy changes in the vocal cord mucosa, making epithelial-like changes such as hyperplasia, chemosis and atypical hyperplasia, with a malignant rate of about 6%-22%. It is one of the precancerous lesions of cancer. 2017 WHO latest revised classification of head and neck tumors classifies the pathological types of vocal cord leukoplakia into low-grade heterogeneous hyperplasia and high-grade heterogeneous hyperplasia[9].
It has been found that a high inflammatory response and low nutritional status can promote the progression of cancer cells, which is one of the main manifestations in patients with laryngeal squamous cell carcinoma. The inflammatory response stimulates the release of multiple inflammatory mediators, vascular endothelial growth factor, which contributes to cardiovascular production to promote tumor growth. Inflammation can participate in tumor occurrence and development by accelerating tumor cell proliferation, migration, angiogenesis, and suppressing the body's anti-tumor immunity, etc. The nutritional and inflammatory immune status of the body is related to the clinicopathological characteristics of malignant tumors and affects the clinical treatment outcome and prognosis.
In recent years, NLR which reflect the nutritional changes of tumor-related inflammation, have become the focus of new research. NLR is a systemic inflammatory biomarker based on neutrophils and lymphocytes, reflecting the balance between inflammatory and immune responses to malignant tumors, and is a biological indicator closely related to the immune response of the body. Neutrophils and lymphocytes, as major cellular components of the immune system, neutrophils reflect inflammatory status, lymphocytes represent immune regulatory pathways, and NLR may reflect the degree of systemic inflammatory response.
Reactive oxygen species (ROS) are increasingly recognized as critical determinants of cellular signaling and a strict balance of ROS levels must be maintained to ensure proper cellular function and survival. Notably, ROS is increased in cancer cells. The superoxide dismutase family plays an essential physiological role in mitigating deleterious effects of ROS[10]. SOD is capable of converting superoxide anions into hydrogen peroxide and belongs to one of many defensive mechanisms, which prevent from cell oxidative damage, leading to apoptosis[11]. A large volume of evidence suggests that malignant cells increase their antioxidant capacities to prevent tissue damage when ROS levels are increased[12−13],while SOD is an efficient and powerful antioxidant enzyme that acts to decrease the levels of oxidative stress in an organism[14−15],so this can support our view that SOD is associated with laryngeal squamous cell carcinoma. Our study found that SOD levels in patients with laryngeal cancer were lower than those in patients with vocal cord leukoplakia and vocal cord polyps, and the ROC curve showed that SOD was more sensitive than NLR and PIN. In addition, some studies have found that lower lip cancer is positively correlated with the Khmer expression of Mn-SOD[16], which may be due to the different SOD response mechanisms of squamous cell carcinoma in different organs.
In 2017, the Department of Otolaryngology-Head and Neck Surgery, Zhongshan Hospital, Fudan University, reported for the first time the diagnostic value of LMR, NLR in benign laryngeal lesions, precancerous laryngeal lesions, and laryngeal squamous cell carcinoma[17]. However, ROC statistical analysis was not performed, and the specific accuracy and specificity were not calculated. NLR and PNI have diagnostic value for many tumors such as lung, colorectal, liver, breast and kidney cancers[18−19]. Many scholars have examined the predictive value of NLR and PNI on the prognosis of laryngeal cancer[20−21], but few scholars have examined the diagnostic value of NLR and PNI on laryngeal cancer. Meanwhile, SOD is an index that is often overlooked in the hematological examination of liver function. No scholars have examined the diagnostic value of SOD in laryngeal cancer.
Lianyuan Tao found that NLR, CA125 and CA19-9 are associated significantly with lymph node metastasis independently in a multivariate analyses of 159 pancreatic ductal adenocarcinoma patients[22]. Toshiyuki Kosuga[23] thought that preoperative NLR may be a useful complementary diagnostic tool for predicting pathological lymph node metastasis in gastric cancer because of its higher sensitivity and negative predictive value than conventional modalities. Bo Zhou[24] reviewed 101 patients and found that preoperative NLR ≥ 1.80 is independently associated with lymph node metastases for patients undergoing resection of nonfunctioning pancreatic neuroendocrine tumors. Gorkem Eskiizmir[25] retrospectively analyzed the medical records of patients with benign laryngeal tumors, precancerous lesions, and malignant tumors, and found that there was no significant difference in NLR between the three groups, but NLR was a predictor of stage, lymph node metastasis, and distant metastasis. Therefore, they proposed that pretreatment NLR is a useful and reliable marker for predicting lymph node metastasis and prognosis. We did not detect the significance of NLR and SOD in predicting preoperative lymph node metastasis of laryngeal cancer. Maybe it has something to do with our low caseloads.