A Systematic Study On The Relationship Between Plasma Vitamin D Concentration And Prognosis Of Gastric Cancer

Gastric cancer is one of the most common malignancies in the world and is a serious threat to human health.Among them,China is one of the most important countries in the global burden of gastric cancer,and it is of great significance to clarify the relevant influencing factors of gastric cancer development and improve the prevention and treatment of gastric cancer.Among them,there are many clinical and pathological factors affecting the prognosis of gastric cancer,such as age,sex,tumor location,tumor pathology,TNM stage,postoperative chemotherapy and so may have the prognosis of gastric cancer.In addition to the clinical TNM staging,the lack of other indicators can accurately determine the prognosis of patients with gastric cancer.However,with the same TNM stage,the prognosis of them is still significant differences.In this medical background,to seek a new way to determine the prognosis of gastric cancer is the current medical research workers face a major demand.Vitamin D is a fat-soluble steroid derivative,is one of the essential nutrients the body.In recent years,many studies have found that,vitamin Dnot only regulate the body's calcium and phosphorus metabolism,maintenance of calcium and other traditional functions,but can inhibit tumor cell proliferation,induce cell differentiation,promote cell apoptosis as well.A large number of epidemiological studies have also confirmed that peripheral blood vitamin D concentration and tumor prognosis was significantly related,including colorectal cancer,lung cancer,breast cancer,prostate cancer,pancreatic cancer and other tumors.But in the prognosis of gastric cancer,we need the systematic,large sample of epidemiological evidenceTherefore,the relationship between vitamin D and the prognosis of gastric cancer can be used to provide a new factor for predicting the prognosis of gastric cancer.It provides clues for the diagnosis and treatment of malignant tumor.Based on this hypothesis,a large number of population data of public database and genomics data of follow-up laboratory were used to conduct anassociationstudy between plasma vitamin D and prognosis of gastric cancer,and combined with gene polymorphism andpredictive microRNA binding sites,provides epidemiologic and genetic evidence to our hypothesis.Part I.The relationship between the prognosis of gastric cancer and the UV index of patients' residenceA large number of in vitro functional experiments have confirmed that vitamin D in addition to participate in calcium and phosphorus metabolism regulation,but also through a variety of mechanisms to play anti-tumor effect.Epidemiological studies have also found that high plasma vitamin concentrations is tumor prevalence and tumor mortality protection factors,including colorectal cancer,breast cancer,lung cancer and others.But there is no systematic and large sample of epidemiological study in gastric cancer.The National Cancer Institute's "Surveillance,Epidemiology and End Results Program" database(SEER)is one of the most representative large-scale tumor registration databases in North America.The database collects a variety of tumor-related evidence-based medical data,providing detailed data support and valuable research data for clinical medicine research and clinician practice.Researchers confirmed that vitamin D levels in the human body in addition to dietary intake supplement,the UV irradiation after 7-dehydrocholesterol chemical conversion is also an important source.People who livewith high latitudes are more prone to vitamin D deficiency.Epidemiological studies have found that the relationship between the prognosis of cancers,including colorectal cancer,lung cancer and others,and residential areas of the UVB or latitude level.For example high latitudes of patients with tumor prognosis is relatively poor.This study was based on the prognostic information of 46,388 new patients with gastric cancer in 18 regions from 1988 to 2010,and explored the relationship between the UV index of different living areas and the prognosis of gastric cancer in order to find the indirect epidemic evidence of vitamin D and prognosis of gastric cancer.The median survival time was calculated by Kaplan-Meier method,and the differences in survival were compared by log-rank test.The relationship between UVB and gastric cancer survival was analyzed by multivariate Cox regression analysis with adjustment of age,gender,race,marital status,income level,diagnosis years,surgery status,tumor location,histologic type and TNM stage.The association strength is expressed as Hazard Ratio(HR)and its 95%Confidence Interval(CI).Based on the satellite monitoring data provided by the National Aeronautics and Space Administration(NASA),we obtained the annual average UVB radiation index(UVB)for the 18 regions,which registered in the SEER database,from 2000 to 2010.Then we wesorted them into two groups,high UVB(31,970 patients)and low UVB area(14,418 patients).We found a significant difference in median survival timebetween these two groups(13.00 ± 0.15 vs.12.00 ± 0.19 in the high-UVBgroupvs.low-UVBgroup,and the log-rank test P<0.001).Considering that the United States is a multi-ethnic mixed country,there is a huge difference in the absorptive capacity of ultraviolet light among different races.Then we divided the samples into four groups,non-Hispanic white,non-Hispanic Black,non-Hispanic other and Hispanic.In the four groups,we found that,compared with the high UVBgroup,except for Hispanic blacks,in the other three subgroups,showed a significant correlation between the prognosis of gastric cancer and the UVB.Patients with high UVB have better prognosis(after adjustment,in non-Hispanic white,HR=1.05,P=0.001;in non-Hispanic black,HR=0.98,P=0.613;in non-Hispanic others,HR=1.25,P=2.2 x 10'5;in Hispanic,HR=1.08,P=0.024).Further stratification analysis showed the same effect in multiple subgroups of different races,but no heterogeneity was found in subgroups(Pheterogeneity>0.05).In summary,the first part of this study is based on the large sample population of the US SEER database.The UVB of different regions is divided into two groups:high and low in the UVBdifference.Obtained the indirect epidemiological evidence that vitamin D affected the prognosis of gastric cancer,and obtained important information for the next study.Part ?.Relationship among plasma vitamin D,prognosis of gastric cancer and degree of myelosuppressionIn the first part of our study,according to the SEER database,we confirmed the relationship between UVB and the prognosis of gastric cancer,but also provide the evidence to the relationship between vitamin D and gastric cancer prognosis.Based on these findings,we first explored the relationship between plasma vitamin D concentration and gastric cancer prognosis in patients with gastric cancer.Patients with gastric cancer were consecutively recruited between January 2007 and December 2011 from the First Affiliated Hospital of Nanjing Medical University,and Jiangsu University Hospital(Zhenjiang).All patients were newly diagnosed,histopathologically confirmed and sampled 5 ml of peripheral venous blood.The plasma 25-OHD concentration was measured by DiaSorn's 25-OHD radioimmunoassay kit(Stillwater,MN,USA).We use the near/long-term prognosis factors to discuss the asscociation.The median survival time was calculated by Kaplan-Meier method.The differences in the survival of different subgroups were compared by log-rank test.The relationship between plasma concentration of 25-OHD and the degree of inhibition of chemotherapy was studied bymultivariate linear regression.The effects of Progression Free Survival(PFS)and overall Survival(OS)on the concentration of 25-OHD in gastric cancer patients were analyzed by univariate and multivariate Cox regression analysis after adjustingfor age,gender,smoking/drinking status,BMI,TNM staging,surgical type,tumor location,sampling seasons.The association strength is expressed as Hazard Ratio(HR)and its 95%confidence interval(CI).We first analyzed the relationship between plasma concentrations of 25-OHD and PFS in 558 patients with stage ?-?.Cox proportional hazards regression model showed that the PFS of the high 25-OHD concentration group(?42.48 nmol/L)was significantly better than that in the low concentration group(<42.48 nmol/L),which was consistent before and after adjustment(HR=0.68,P=0.003;adjusted HR=0.63,P=0.001).Then we stratified by age,gender,smoking/drinking status,TNM staging andtumor location.The results showed that there were subgroup differences in gender stratification(male vs.female,HR=0.70 vs.HR?0.56,Pheterogeneity?0.038).Then female patients in accordance with the menopause status were divided into two groups,we found that compared with postmenopausal women,the protective effect of plasma 25-OHD in premenopausal women is much stronger(HR=0.12 vs.HR=0.72,Pheterogeneity?0.009).In these 558 patients with stage ?-?,we also found that the plasma 25-OHD concentration was related to the degree of myelosuppression after chemotherapy(before adjustment,?=-0.013,P=0.001;after adjustment,?=-0.012,P=0.003).Additionally,all of the patients weretreated by fluorouracil-based first-line chemotherapy.We then examined the relationship between plasma 25-OHD concentrations and overall survival in patients with stage ?-? gastric cancer.In total 785 subjects,we found that plasma 25-OHD concentrations were also significantly associated with OS in patients with gastric cancer by univariate and multivariate Cox proportional hazards regression model.In this part of the subjects,according to theconcentrationof the plasma 25-OHD,we divided the patients into three groups.Compared with the lowest concentration Tertile 1(<36.66nmol/L),the highest concentration Tertile 3(>48.93nmol/L)has significantly better OS(before adjustment,HR=0.48,P=3.34 ×10-6;after adjustment HR=0.41,P=1.28 × 10-7).Similarly,we stratified by baseline data and found that there were also differences in the sex group(T3 vs.T1,male vs.female,HR=0.52 vs.HR=0.20,Pheterogeneity=0.030).And the protective effect of plasma 25-OHD in premenopausal women was stronger(Pheterogeneity<0.05).In this part,based on the data of our study,the plasma 25-OHD concentration in patients with gastric cancer was measured on the basis of tranditional epidemiological survival research.Through the progression-free survival and overall survival,we confirmed that a higher concentration of plasma 25-OHD can provide a better prognosis for patients with gastric cancer,in which premenopausal women plasma 25-OHD protective effect stronger.In addition,in the ?-? stage of gastric cancer patients,plasma 25-OHD concentration is associated with the degree of myelosuppressionafter fluorouracil-basedfirst-line chemotherapy;higher 25-OHD concentration means lower degree of myelosuppression.The results of this study have laid a theoretical foundation for further research on the genetic aspects of the study,and explored a new direction for the study of new prognostic factors for gastric cancer.It also provides a new idea for adjuvant therapy for gastric cancer,with important theoretical and clinical significance.Part ?.The association between polymorphisms in VDR/RXRA genes and gastric cancer survivalIn the second part of our study,we confirmed that plasma 25-OHD concentration of gastric cancer patientswas associated with gastric cancer survival.In order to obtain further genetic evidence,we explore association between the genetic variants in vitamin D metabolic pathway-related genesand the prognosis of gastric.After reviewing the literature,we found that the heterodimer formed by the combination of VDR/RXRA protein in the metabolism of vitamin D in human body plays an important role in activating the biological effects of 25-OHD.Therefore,we detected the genotyping of 12 potential functional single nucleotide polymorphisms(SNP)loci on two genes of VDR/RXRA through the Sequenom MassARRAY platform.Then weput the genotypes into univariate and multivariate Cox proportional hazards regression model,to determine whether these SNP sites were associated with gastric cancer prognosis.Finally,we used bioinformatics analysis to predict the possible binding of positive sites to microRNAs.We identified that two SNPs in RXRA(rs4240711 and rs1045570)and two SNPs in VDR(rs2228570 and rs3847987)were significantly associated with prognosis of GC patients after multiple testing correction(P<0.05/12).The details are as follows,rs2228570,HR=1.81,Ptrend=6.28×10-4;rs3847987,HR=1.75,Ptrend=0.009;rs4240711,HR=2.03,Ptrend=0.004;rs1045570,HR=2.03,Ptrend=0.003.The results of the joint analysis of these four positive loci showed that the risk of death in patients with 2 and 3?6 risk alleles was higher in the adjusted outcome compared with individuals carrying 0-1 hazard alleles,which increased by 48%(HR=1.48,P=0.04)and 118%(HR=2.18,P=6.67 × 10-6).Then,the gene-environment interaction analysis of gastric cancer survival and SNPs showed that there was a marginal positive result(P=0.09)in rs1045570.By further stratification analysis,we found that only in the tumor location of gastric cancer,there was a significant interaction(Pinteraction=0.03)in patients with cardia/fundus.In summary,the third part of this study provides genetic evidence for the plasma 25-OHD concentrations found in the previous part.We confirmed that the SNPs in VDR/RXRA genes were significantly associated with the prognosis of gastric cancer.The results of this part are an important addition to the results of the second part,suggesting that 25-OHD plays a protective role in people who suffering from gastric cancer,and whether it is necessary for future gastric cancer patients to supplement certain vitamin D to assist in anti-tumor therapy,and which subgroups of patients are more suitable for vitamin D support.