CLINICAL AND MORPHOLOGICAL CHARACTERISTICS OF NSCLC AND VEGF GENE POLYMORPHISM

Mikhail N. Shapetska 1 , Anna N. Shchayuk 2 , Elena P. Mikhalenko , Natalia V. Chebotareva, Svetlana N. Pisarchik 3 and Evelina V. Krupnova 2 . 1. Belarusian State Medical University, Minsk, Republic of Belarus. 2. Institute of Genetics and Cytology NAS of Belarus, Minsk, Republic of Belarus, 3. City Clinical Pathologoanatomic Bureau, Minsk, Republic of Belarus. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Our study shown prognostic effect of VEGF gene polymorphisms on clinical features of NSCLC. As vascular endothelial growth factor (VEGF) is a major driver of angiogenesis and cancer cells proliferation, we evaluated survival the group of patients with NSCLC from the position of VEGF gene polymorphisms, TNM and histological types of tumor. Analysis revealed that polymorphisms VEGF gene influence the outcome of treatment, histological type, size, metastasis as aggressiveness of the NSCLC.
In lung cancer, the prognosis mainly depends on the disease stage, histological characteristics and metastatic potential of the primary tumor. Following the combined/complex treatment of non-small cell lung cancer (NSCLC), the survival at stage 1 of the disease makes 40-50%, at stage 2 -15-30% [http://bioinfo.iconcologia.net/snpstats/start.htm]. In advanced cases or unrespectable tumors, the radiotherapy results in a 5-year survival in 4-8% of patients only. Up to 90% of patients die within the first two years after the diagnosis if a special treatment is not given. The mediastinal lymph nodes involvement dramatically reduces the life expectancy for NSCLC patients in particular. Even a single mediastinal lymph node invasion is considered to be an unfavorable prognostic factor in NSCLC (Peng Lv., 2014) The aggressive clinical course is typical for the squamous cell cancer as well as for adenocarcinoma due to their histological structure. However, the difference in the life expectancy can vary depending on the degree of the neoplasm differentiation. Well differentiated adenocarcinoma and squamous cell cancer are less aggressive as compared to poorly differentiated carcinomas, which early spread to mediastinal lymph nodes (Furrukh, et al. 2013).
Individual genetic features of patients may affect the prognosis for NSCLC clinical course. Taking into account multiple aspects when assessing the prognosis and choosing an adequate treatment strategy for malignancies, one of the main oncological issues nowadays is to study the role of growth factors in neoangiogenesis.

Results:-
Clinical characteristics of NSCLC patients are shown in Table 1.The median age was 61,4 years (age range 36 to 92 years), male-female ratio was 1:3 (22,8%females : 77,2% males). 56, 8 % of patients were cigarette smokers at the time of the surgery, 33, 3% never smoked, and the smoking status is not known in 9,9%. The patients have been surgical treated according to the degree of tumor spreading and their functional condition. Lobectomy/bilobectomy or atypical resection was performed in 68, 5% of patients. 27% of subjects underwent pneumonectomy. In 4% of cases, only the pulmonary biopsy was carried out, with the surgery not done because of poor lung capacity.  When the tumor spreads to the mediastinal lymph nodes, the criterion N was the most significant for predicting the survival in NSCLC in the study group. Patients with not involved mediastinal lymph nodes have the best survival prognosis. A 3-year survival for N0 made 73,5%, a 5-year survival -59,0%. With a single lymph node being involved, the prognosis dramatically worsened. 3-year survival for patients with N1, depending on the tumor spread to the regional lymph nodes of the mediastinum was 46,0% (Gehan test = 2,75; p = 0,006). Only 1 patient survived the disease for more than 5 years.
The more lymph nodes were involved, the worse prognosis was observed. According to our data, a 3-year survival for patients with N2 made 33%. Only 1 patient at N1 approached a 5-year survival. No one patient at N3 survived the disease for more than 3 or 5 years. The median life expectancy for patients with N0 accounted to 22,6 months, N1 -10,7 months, N2 -9,3 months, and N3 -2,4 months. The data were statistically significant for the group in general, (p=0,005), but the results of Gehan-Wilcoxon test sand p-values for each N group were different. The involvement of more than one lymph node has been to reduce the overall survival in lung cancer significantly ( Morphological characteristics of the tumor are also a very informative factor affecting the survival rate of patients with NSCLC. In squamous cell cancer due to early metastases spread, the outcomes of treatment could be worse as compared to those in carcinomas ( Figure 4). In our study, a 3-year survival of patients with squamous cell cancer was 51,3%, a 5-year survival -43,0%. A 3-year survival of patients with adenocarcinoma was 78,7%, a 5-year survival -63,5%. Thus, the patients with adenocarcinoma have more chances to survive the disease for more than 5 years as compared to those with squamous cell cancer (p=0,08).
1808  (Table  2). Table 3 shows the results of association of polymorphisms rs2010963, rs699947, rs3025039 of gene VEGF with morphological tumor type and development of NSCLC (tumor size, disease stage and metastasis). It is shown that polymorphic variant + 936TT VEGF gene is significantly more frequent in patients with squamous cell lung cancer (OR = 4,37 CI: 1,09-24,63; p = 0.049 ). The influence of polymorphism rs699947 VEGF gene on the clinical characteristics of the tumor has been revealed. A greater degree of spread of the tumor (T2 -T4) was observed in patients with genotype -2578CC more frequently (p = 0.005). Patients with genotype -2578AA are significantly less likely to have the 3rd stage of the disease (p = 0.012), develop less metastasis of the primary tumor in the regional lymph nodes (p = 0.0098) and do not develop multiple lesions of lymph nodes, compared to patients with genotype -2578CC. Haplotype analysis (Table 4) of the three studied polymorphisms of the VEGF gene showed significant association of haplotype -634C / -2578C / + 936C with a small non-invasive cancer (p = 0.0068). Haplotype carriers -634G / -2578C / + 936C revealed high aggressiveness of the disease (stage -p = 0.0061; regional metastasis -p = 0.0014). The above mentionned fact might explain that there is a greater degree of tumor spread in homozygous carriers in our study (-2578CC). Lower levels of VEGF expression in the presence of -2578A allele apparently provides a protective effect in homozygous genotypes (-2578AA) carriers associated with a lower spreading of tumors (Table  3).

Discussion:-
High levels of VEGF expression is associated with increased risk of disease recurrence and decreased survival rates of people with a variety of oncological processes (Awata, T., et al., 2002). We can assume it is the contribution of the genotype (-2578CC) VEGF, that determines the high level of expression of the corresponding protein product in the progression of NSCLC, which has been confirmed by our research. We