Circulating Biomarkers in Patients with Head and Neck Cancer and the Influence of Cigarette Smoking

Abstract: Head and neck cancer (HNC) is a collective name for heterogeneous tumors located in the head and neck regions for which smoking, alcohol and human papillomavirus (HPV) are documented risk factors. The survival of HNC patients has only improved marginally during the last decade. The most important prognostic factors are tumor size, local spread and distant metastases, tumor node metastasis (TNM) staging. Prognostic biomarkers are needed as a complement to TNM staging.The aim for this thesis was to investigate rapid and low cost blood based biomarkers which could indicate the risk of HNC, recurrence of the disease or the survival of HNC patients. Furthermore, the aim was to examine how cigarette smoking influences the levels of biomarkers.In paper I, a possible role of plasma cytokines or proteins associated with immune response or inflammation, as biomarkers for the survival of HNC patients was investigated. Higher levels of C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-α) were detected in plasma of the patients compared with the levels in the controls. The elevated levels of these two biomarkers detected in patients were associated with decreased survival.In paper II, the influence of 45 single nucleotide polymorphisms (SNPs) located in 41 genes associated with cell cycle progression, cell death, DNA repair or immune response on cancer risk, tumor recurrence and survival in HNC patients were investigated. SNPs in immune response genes were associated with risk for HNC, an elevated risk for recurrence and a decreased survival in HNC patients.In paper III, the influence of cigarette smoking on levels of inflammatory cells, proteins or cytokines/chemokines, microRNAs (miRNAs) and SNPs was analysed in healthy smokers and non-smokers. Higher levels of total white blood cells (WBCs), neutrophils, monocytes, lymphocytes, neutrophil to lymphocyte ratio (NLR), CRP, monocyte chemoattractant protein- 1 (MCP-1) and interferon gamma (IFN-γ) were detected in smokers compared to non-smokers and indicate an inflammatory response. Also, a lower level of oncomiRNA miR-21was detected in smokers. This alteration, in combination with the elevated levels of IFN-γ in smokers could be a protective response to cigarette smoke. The higher levels of IFN-γ in smokers compared to non-smokers were however only detected in individuals with SNP rs2069705 genotype AG/GG. This indicates a genetic association of the levels of IFN-γ.In paper IV, the separate effects of cigarette smoking and HNC on inflammatory or immune biomarkers and the impact of high risk human papillomavirus, age and gender were investigated. Comparisons of circulating levels of WBCs and its subpopulations, plasma proteins or cytokines/chemokines between smoking and non-smoking patients, smoking and non-smoking controls and between the patient and control groups were analysed. Smoking had highest impact on elevated levels of WBCs, IFN-γ and MCP-1, and HNC had highest impact on elevated levels of neutrophils, monocytes, NLR, CRP, macrophage inflammatory protein 1 beta and TNF-α.In conclusion, host immune response associated parameters could be suitable as biomarkers for the risk of HNC, risk of recurrence or in predicting survival of HNC patients. This thesis show that HNC are associated with systemic inflammatory response and upregulated CRP and TNF-α is related to shorter survival in HNC patients. Additionally, SNPs in immune response genes such as rs1800629 in the TNF-α gene indicates a risk for HNC or an elevated risk for recurrence and a decreased survival in HNC patients. These rapid and low cost blood based biomarkers could be used in combination or as a supplement to established biomarkers in the clinic for a more personalized treatment modality.

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