Polymorphisms in MMP-1, MMP-2, MMP-7, MMP-13 and MT2A do not contribute to breast, lung and colon cancer risk in polish population.

BACKGROUND: Matrix metalloproteinases (MMPs) and metallothioneins (MTs) are Zinc-related proteins which are involved in processes crucial for carcinogenesis such as angiogenesis, proliferation and apoptosis. Several single nucleotide polymorphisms (SNPs) in MMPs and MTs that affect genes expression have been associated with cancer risk, including breast, lung and colon. METHODS: The study group consisted of 648 unselected patients (299 with breast cancer, 199 with lung cancer, 150 with colon cancer) and 648 unaffected individuals. Five SNPs, rs1799750 in MMP-1, rs243865 in MMP-2, rs11568818 in MMP-7, rs2252070 in MMP-13 and rs28366003 in MT2A were genotyped and serum zinc (Zn) level was measured. The cancer risk was calculated using multivariable logistic regression with respect to Zn. RESULTS: None of the 5 tested polymorphisms showed a correlation with cancer risk in studied groups, although for MMP-2, MMP-7 and MT2A non-significant differences in genotypes frequencies among cases and controls were observed. CONCLUSIONS: Analyses of polymorphisms, rs1799750 in MMP-1, rs243865 in MMP-2, rs11568818 in MMP-7, rs2252070 in MMP-13 and rs28366003 in MT2A in relation to serum Zn level did not show significant association with breast, lung and colon cancer risk among polish patients. Further studies are needed to verify this observation.

Iron levels, genes involved in iron metabolism and antioxidative processes and lung cancer incidence.

BACKGROUND: Lung cancer is the most common adult malignancy accounting for the largest proportion of cancer related deaths. Iron (Fe) is an essential trace element and is a component of several major metabolic pathways playing an important role in many physiological processes. In this study we evaluated the association between Fe concentration in serum, iron metabolism parameters and genetic variaton in 7 genes involved in iron metabolism and anti-oxidative processes with the incidence of lung cancer in Poland. MATERIALS AND METHODS: The study included 200 lung cancer patients and 200 matched healthy control subjects. We analyzed serum iron concentration and iron metabolism parameters (TIBC, UIBC, serum ferritin and transferrin saturation), and genotyped seven variants in seven genes: HFE, TFR1, HAMP, TF, SOD2, CAT and GPX1. RESULTS: Lung cancer patients compared to their matched controls had significantly higher mean serum iron level (p = 0.01), ferritin level (p = 0.007) and TIBC (p = 0.006). Analysis revealed that higher concentration of iron and ferritin (IVth quartile) compared to the lower concentration (Ist quartile) was associated with over 2-fold increased lung cancer incidence. We also found that higher transferrin saturation (p = 0.01) and lower TIBC (p<0.01) are associated with better survival of lung cancer patients. The analysis of polymorphisms in iron related genes did not reveal a significant difference between lung cancer patients and controls. However, rs10421768 in HAMP showed a borderline statistically significant correlation with lung cancer risk (OR = 2.83, p = 0.05). CONCLUSIONS: The results of this case control study indicate that higher body iron represented by higher Fe and ferritin levels may be associated with lung cancer incidence. Rs10421768 in HAMP may be associated with about 3-times higher lung cancer risk. Higher Fe body content may be associated with better survival of lung cancer patients.

Serum selenium level and cancer risk: a nested case-control study.

BACKGROUND: Epidemiologic studies have demonstrated a relationship between selenium status and cancer risk among those with low selenium levels. It is of interest to prospectively evaluate the relationship between selenium and cancer among women who reside in a region with ubiquitously low selenium levels. METHODS: We performed a nested case-control study of baseline serum selenium levels and cancer risk using data and biological samples from 19,573 females that were participants in a biobanking initiative between 2010 and 2014 in Szczecin Poland. Cases included women with any incident cancer (n = 97) and controls (n = 184) were women with no cancer at baseline or follow-up. Serum selenium was quantified using mass spectroscopy. RESULTS: The odds ratio associated being below the cutoff of 70.0 µg/L compared to a level above 70.0 µg/L was 2.29 (95% CI 1.26-4.19; P = 0.007). The risks for women in the two middle categories were similar and suggests that the normal range be between 70 µg/L and 90 µg/L. There was evidence for an increased risk of cancer among women in the highest category of selenium levels (i.e., > 90 µg/L), but this association did not achieve statistical significance (OR = 1.63; 95%CI 0.63-4.19; P = 0.31). CONCLUSIONS: Results from this study suggest that suggest that the optimum serum level of selenium in women living in Poland should be between 70 µg/L and 90 µg/L.

Association of zinc level and polymorphism in MMP-7 gene with prostate cancer in Polish population.

INTRODUCTION: Prostate cancer is one of the most commonly diagnosed malignancies among men in Western populations. Evidence reported in the literature suggests that zinc may be related to prostate cancer. In this study we evaluated the association of serum zinc levels and polymorphisms in genes encoding zinc-dependent proteins with prostate cancer in Poland. METHODS: The study group consisted of 197 men affected with prostate cancer and 197 healthy men. Serum zinc levels were measured and 5 single nucleotide polymorphisms in MMP-1, MMP-2, MMP-7, MMP-13, MT2A genes were genotyped. RESULTS: The mean serum zinc level was higher in prostate cancer patients than in healthy controls (898.9±12.01 µg/l vs. 856.6±13.05 µg/l, p<0.01). When compared in quartiles a significant association of higher zinc concentration with the incidence of prostate cancer was observed. The highest OR (OR = 4.41, 95%CI 2.07-9.37, p<0.01) was observed in 3rd quartile (>853.0-973.9 µg/l). Among five analyzed genetic variants, rs11568818 in MMP-7 appeared to be correlated with 2-fold increased prostate cancer risk (OR = 2.39, 95% CI = 1.19-4.82, p = 0.015). CONCLUSION: Our results suggest a significant correlation of higher serum zinc levels with the diagnosis of prostate cancer. The polymorphism rs11568818 in MMP-7 gene was also associated with an increased prostate cancer risk in Poland.

Serum folate concentration and the incidence of lung cancer.

BACKGROUND: Lung cancer is a leading cause of cancer-related mortality globally. Folate helps to maintain DNA integrity and to regulate gene expression. Serum folate levels may affect the risk of several cancers, including lung cancer. In this study we evaluated the association between serum folate concentration and variations in genes involved in folate metabolism with lung cancer incidence in Poland. METHODS: The study included 366 lung cancer patients and 366 control subjects. We measured serum folate concentration and genotyped six variants in MTHFR, MTR and MTRR genes. The odds ratios of being diagnosed with lung cancer were calculated using conditional univariable and multivariable logistic regression with respect to folate level and genotypes. RESULTS: The mean serum folate level was lower in lung cancer cases than in control group (20.07 nmol/l vs. 22.52 nmol/l, p = 0.002). The odds ratio for lung cancer declined with increasing serum content of the folate. The folate concentration of >25.71 nmol/l (IVth quartile) in comparison to <15.92 nmol/l (Ist quartile) was associated with an odds ratio of 0.61 (95%CI 0.40-0.95, p = 0.03). The analysis of variations in MTHFR, MTR and MTRR genes did not reveal any significant difference between lung cancer cases and controls in univariable and multivariable analyses. CONCLUSION: In this case-control study, lower serum folate concentrations were associated with a higher risk of lung cancer diagnosis. Although previous findings have been somewhat mixed, our results add to the evidence that circulating folate levels may be an indicator of lung cancer risk.

Serum 25(OH)D concentration, common variants of the VDR gene and lung cancer occurrence.

The first aim of our study was to examine the association between common variants in VDR [rs2228570 (FokI), rs1544410 (BsmI), rs7975232 (ApaI), rs731236 (TaqI) and rs11568820 (Cdx2)] and lung cancer risk in the Polish population. Genotyping and statistical analysis which included Chi-square test with Yates correction and haplotype frequency analysis were performed on a series of 840 consecutively collected lung cancer patients and 920 healthy controls. The second aim was to evaluate the link between serum 25(OH)D concentration and the number of lung cancers in a subgroup of 200 patients. A separate control group that consisted of 400 matched (by age, sex, smoking habits and the season of blood collection) healthy individuals was used to avoid posterior adjustment on the matched variables. Statistical analysis with the use of Chi-square test with Yates was performed. We found no statistically significant difference in the distribution of the allels of studied VDR variants among cases and controls. A statistically significant over-representation of VDR haplotypes: rs731236_A + rs1544410_T [odds ratio (OR) = 2.43, 95% confidence interval (CI) = 1.11-5.32, p < 0.001], rs731236_G + rs1544410_T (OR = 1.54, 95% CI = 1.31-1.81, p < 0.001) and rs731236_G + rs1544410_C (OR = 0.04, 95% CI = 0.03-0.07, p < 0.001) was detected. We found a tendency toward an increased number of lung cancers among individuals with low serum levels of 25(OH)D. To answer the question, whether VDR can be regarded as lung cancer susceptibility gene and low 25(OH)D serum levels is associated with lung cancer occurrences, additional, multicenter study needs to be performed.

Inheritance of deleterious mutations at both BRCA1 and BRCA2 in an international sample of 32,295 women.

BACKGROUND: Most BRCA1 or BRCA2 mutation carriers have inherited a single (heterozygous) mutation. Transheterozygotes (TH) who have inherited deleterious mutations in both BRCA1 and BRCA2 are rare, and the consequences of transheterozygosity are poorly understood. METHODS: From 32,295 female BRCA1/2 mutation carriers, we identified 93 TH (0.3 %). "Cases" were defined as TH, and "controls" were single mutations at BRCA1 (SH1) or BRCA2 (SH2). Matched SH1 "controls" carried a BRCA1 mutation found in the TH "case". Matched SH2 "controls" carried a BRCA2 mutation found in the TH "case". After matching the TH carriers with SH1 or SH2, 91 TH were matched to 9316 SH1, and 89 TH were matched to 3370 SH2. RESULTS: The majority of TH (45.2 %) involved the three common Jewish mutations. TH were more likely than SH1 and SH2 women to have been ever diagnosed with breast cancer (BC; p = 0.002). TH were more likely to be diagnosed with ovarian cancer (OC) than SH2 (p = 0.017), but not SH1. Age at BC diagnosis was the same in TH vs. SH1 (p = 0.231), but was on average 4.5 years younger in TH than in SH2 (p < 0.001). BC in TH was more likely to be estrogen receptor (ER) positive (p = 0.010) or progesterone receptor (PR) positive (p = 0.013) than in SH1, but less likely to be ER positive (p < 0.001) or PR positive (p = 0.012) than SH2. Among 15 tumors from TH patients, there was no clear pattern of loss of heterozygosity (LOH) for BRCA1 or BRCA2 in either BC or OC. CONCLUSIONS: Our observations suggest that clinical TH phenotypes resemble SH1. However, TH breast tumor marker characteristics are phenotypically intermediate to SH1 and SH2.

BRCA1 founder mutations do not contribute to increased risk of gastric cancer in the Polish population.

BACKGROUND: Gastric cancer (GC) is part of the spectrum of diseases linked to BRCA1 and BRCA2 mutations that increase the risk of breast and ovarian cancer. Data suggesting an increased risk of developing GC among BRCA1 and BRCA2 mutation carriers are based almost exclusively on indirect studies. The objective was to assess in a direct study whether there is a relationship between GC and selected recurrent BRCA1 and BRCA2 mutations in the Polish population. METHODS: Three hundred seventeen GC patients (193 males and 124 females; mean age 59.5 ± 12.8 y) diagnosed at the Department of Gastroenterology at the Pomeranian Medical University were included in this retrospective study. All patients were genotyped for 3 BRCA1 Polish founder mutations (5382insC, C61G and 4153delA) as well as for 9 known recurrent mutations in BRCA1 and BRCA2 genes. Genotyping was performed using allele-specific oligonucleotide polymerase chain reaction (ASA-PCR) for 4153delA and 5382insC, restriction fragment length polymorphism (PCR-RFLP) for C61G and TaqMan real-time PCR for 185delAG, 3819del5, 3875del4, 5370C > T, 886delGT, 4075delGT, 5467insT, 6174delT and 8138del5. RESULTS: Among tested mutations one founder BRCA1 mutation 5382insC was detected in two of 317 (0.63 %) GC cases. A comparison of frequency of detected BRCA1 founder mutations in GC patients to previously described 4570 Polish controls (0.63 % vs. 0.48 %) failed to indicate an increased risk of GC in the mutation carriers (OR = 1.3; 95 % CI 0.3-5.6, p = 0.71). A comparison of frequency of GC male cases and male controls (1.0 % vs. 0.43 %,OR = 1.5; 95 % CI 0.3-6.4, p = 0.61) allowed to formulate the same conclusion that there is no increased risk for GC for males. None of the 9 recurrent BRCA1 and BRCA2 mutations has been detected in tested GC patients. CONCLUSION: The current study indicates that founder BRCA1 mutations reported in Polish breast/ovarian cancer patients do not contribute to increased GC risk. The nine tested recurrent BRCA1 and BRCA2 mutations were not detected in GC patients which may suggests that they are rare in GC patients in the Polish population. Further analyses, including sequencing of entire sequences of BRCA1 and BRCA2 genes, are necessary to ultimately determine the role of these two genes in GC in Poland.

Serum Concentrations of Selenium and Copper in Patients Diagnosed with Pancreatic Cancer.

PURPOSE: Understanding of the etiology and pathogenesis of pancreatic cancer (PaCa) is still insufficient. This study evaluated the associations between concentrations of selenium (Se) and copper (Cu) in the serum of PaCa patients. MATERIALS AND METHODS: The study included 100 PaCa patients and 100 control subjects from the same geographical region in Poland. To determine the average concentration of Se, Cu, and ratio Cu:Se in the Polish population, assay for Se and Cu was performed in 480 healthy individuals. Serum levels of Se and Cu were measured using inductively coupled plasma mass spectrometry. RESULTS: In the control group, the average Se level was 76 µg/L and Cu 1,098 µg/L. The average Se level among PaCa patients was 60 µg/L and the mean Cu level was 1,432 µg/L. The threshold point at which any decrease in Se concentration was associated with PaCa was 67.45 µg/L. The threshold point of Cu level above which there was an increase in the prevalence of PaCa was 1,214.58 µg/L. In addition, a positive relationship was observed between increasing survival time and Se plasma level. CONCLUSION: This retrospective study suggests that low levels of Se and high levels of Cu might influence development of PaCa and that higher levels of Se are associated with longer survival in patients with PaCa. The results suggest that determining the level of Se and Cu could be incorporated into a risk stratification scheme for the selection and surveillance control examination to complement existing screening and diagnostic procedures.

Prevalence of Germline Mutations in Genes Engaged in DNA Damage Repair by Homologous Recombination in Patients with Triple-Negative and Hereditary Non-Triple-Negative Breast Cancers.

PURPOSE: This study sought to assess the prevalence of common germline mutations in several genes engaged in the repair of DNA double-strand break by homologous recombination in patients with triple-negative breast cancers and hereditary non-triple-negative breast cancers. Tumors deficient in this type of DNA damage repair are known to be especially sensitive to DNA cross-linking agents (e.g., platinum drugs) and to poly(ADP-ribose) polymerase (PARP) inhibitors. METHODS: Genetic testing was performed for 36 common germline mutations in genes engaged in the repair of DNA by homologous recombination, i.e., BRCA1, BRCA2, CHEK2, NBN, ATM, PALB2, BARD1, and RAD51D, in 202 consecutive patients with triple-negative breast cancers and hereditary non-triple-negative breast cancers. RESULTS: Thirty five (22.2%) of 158 patients in the triple-negative group carried mutations in genes involved in DNA repair by homologous recombination, while 10 (22.7%) of the 44 patients in the hereditary non-triple-negative group carried such mutations. Mutations in BRCA1 were most frequent in patients with triple-negative breast cancer (18.4%), and mutations in CHEK2 were most frequent in patients with hereditary non-triple-negative breast cancers (15.9%). In addition, in the triple-negative group, mutations in CHEK2, NBN, and ATM (3.8% combined) were found, while mutations in BRCA1, NBN, and PALB2 (6.8% combined) were identified in the hereditary non-triple-negative group. CONCLUSIONS: Identifying mutations in genes engaged in DNA damage repair by homologous recombination other than BRCA1/2 can substantially increase the proportion of patients with triple-negative breast cancer and hereditary non-triple-negative breast cancer who may be eligible for therapy using PARP inhibitors and platinum drugs.

Assessing associations between the AURKA-HMMR-TPX2-TUBG1 functional module and breast cancer risk in BRCA1/2 mutation carriers.

While interplay between BRCA1 and AURKA-RHAMM-TPX2-TUBG1 regulates mammary epithelial polarization, common genetic variation in HMMR (gene product RHAMM) may be associated with risk of breast cancer in BRCA1 mutation carriers. Following on these observations, we further assessed the link between the AURKA-HMMR-TPX2-TUBG1 functional module and risk of breast cancer in BRCA1 or BRCA2 mutation carriers. Forty-one single nucleotide polymorphisms (SNPs) were genotyped in 15,252 BRCA1 and 8,211 BRCA2 mutation carriers and subsequently analyzed using a retrospective likelihood approach. The association of HMMR rs299290 with breast cancer risk in BRCA1 mutation carriers was confirmed: per-allele hazard ratio (HR) = 1.10, 95% confidence interval (CI) 1.04-1.15, p = 1.9 x 10(-4) (false discovery rate (FDR)-adjusted p = 0.043). Variation in CSTF1, located next to AURKA, was also found to be associated with breast cancer risk in BRCA2 mutation carriers: rs2426618 per-allele HR = 1.10, 95% CI 1.03-1.16, p = 0.005 (FDR-adjusted p = 0.045). Assessment of pairwise interactions provided suggestions (FDR-adjusted pinteraction values > 0.05) for deviations from the multiplicative model for rs299290 and CSTF1 rs6064391, and rs299290 and TUBG1 rs11649877 in both BRCA1 and BRCA2 mutation carriers. Following these suggestions, the expression of HMMR and AURKA or TUBG1 in sporadic breast tumors was found to potentially interact, influencing patients' survival. Together, the results of this study support the hypothesis of a causative link between altered function of AURKA-HMMR-TPX2-TUBG1 and breast carcinogenesis in BRCA1/2 mutation carriers.

Selenium as a marker of cancer risk and of selection for control examinations in surveillance.

Publication is summarization of existing data being results of literature review and our experience on usefulness of selenium as a diagnostic marker selection for control examinations in surveillance and as a marker of patients with high risk of cancers.

Methylation of the BRCA1 promoter in peripheral blood DNA is associated with triple-negative and medullary breast cancer.

It has been proposed that methylation signatures in blood-derived DNA may correlate with cancer risk. In this study, we evaluated whether methylation of the promoter region of the BRCA1 gene detectable in DNA from peripheral blood cells is a risk factor for breast cancer, in particular for tumors with pathologic features characteristic for cancers with BRCA1 gene mutations. We conducted a case-control study of 66 breast cancer cases and 36 unaffected controls. Cases were triple-negative or of medullary histology, or both; 30 carried a constitutional BRCA1 mutation and 36 did not carry a mutation. Blood for DNA methylation analysis was taken within three months of diagnosis. Methylation of the promoter of the BRCA1 gene was measured in cases and controls using methylation-sensitive high-resolution melting (MS-HRM). A sample with any detectable level of methylation was considered to be positive. Methylation of the BRCA1 promoter was detected in 15 of 66 cases and in 2 of 36 controls (OR 5.0, p = 0.03). Methylation was present in 15 of 36 women with breast cancer and without germline BRCA1 mutation, but in none of 30 women with breast cancer and a germline mutation (p < 0.01). The association between methylation and breast cancer was restricted to women with no constitutional BRCA1 mutation (OR 12.1, p = 0.0006). Methylation of the promoter of the BRCA1 gene detectable in peripheral blood DNA may be a marker of increased susceptibility to triple-negative or medullary breast cancer.

Common non-synonymous SNPs associated with breast cancer susceptibility: findings from the Breast Cancer Association Consortium.

Candidate variant association studies have been largely unsuccessful in identifying common breast cancer susceptibility variants, although most studies have been underpowered to detect associations of a realistic magnitude. We assessed 41 common non-synonymous single-nucleotide polymorphisms (nsSNPs) for which evidence of association with breast cancer risk had been previously reported. Case-control data were combined from 38 studies of white European women (46 450 cases and 42 600 controls) and analyzed using unconditional logistic regression. Strong evidence of association was observed for three nsSNPs: ATXN7-K264R at 3p21 [rs1053338, per allele OR = 1.07, 95% confidence interval (CI) = 1.04-1.10, P = 2.9 × 10(-6)], AKAP9-M463I at 7q21 (rs6964587, OR = 1.05, 95% CI = 1.03-1.07, P = 1.7 × 10(-6)) and NEK10-L513S at 3p24 (rs10510592, OR = 1.10, 95% CI = 1.07-1.12, P = 5.1 × 10(-17)). The first two associations reached genome-wide statistical significance in a combined analysis of available data, including independent data from nine genome-wide association studies (GWASs): for ATXN7-K264R, OR = 1.07 (95% CI = 1.05-1.10, P = 1.0 × 10(-8)); for AKAP9-M463I, OR = 1.05 (95% CI = 1.04-1.07, P = 2.0 × 10(-10)). Further analysis of other common variants in these two regions suggested that intronic SNPs nearby are more strongly associated with disease risk. We have thus identified a novel susceptibility locus at 3p21, and confirmed previous suggestive evidence that rs6964587 at 7q21 is associated with risk. The third locus, rs10510592, is located in an established breast cancer susceptibility region; the association was substantially attenuated after adjustment for the known GWAS hit. Thus, each of the associated nsSNPs is likely to be a marker for another, non-coding, variant causally related to breast cancer risk. Further fine-mapping and functional studies are required to identify the underlying risk-modifying variants and the genes through which they act.

A large-scale assessment of two-way SNP interactions in breast cancer susceptibility using 46,450 cases and 42,461 controls from the breast cancer association consortium.

Part of the substantial unexplained familial aggregation of breast cancer may be due to interactions between common variants, but few studies have had adequate statistical power to detect interactions of realistic magnitude. We aimed to assess all two-way interactions in breast cancer susceptibility between 70,917 single nucleotide polymorphisms (SNPs) selected primarily based on prior evidence of a marginal effect. Thirty-eight international studies contributed data for 46,450 breast cancer cases and 42,461 controls of European origin as part of a multi-consortium project (COGS). First, SNPs were preselected based on evidence (P < 0.01) of a per-allele main effect, and all two-way combinations of those were evaluated by a per-allele (1 d.f.) test for interaction using logistic regression. Second, all 2.5 billion possible two-SNP combinations were evaluated using Boolean operation-based screening and testing, and SNP pairs with the strongest evidence of interaction (P < 10(-4)) were selected for more careful assessment by logistic regression. Under the first approach, 3277 SNPs were preselected, but an evaluation of all possible two-SNP combinations (1 d.f.) identified no interactions at P < 10(-8). Results from the second analytic approach were consistent with those from the first (P > 10(-10)). In summary, we observed little evidence of two-way SNP interactions in breast cancer susceptibility, despite the large number of SNPs with potential marginal effects considered and the very large sample size. This finding may have important implications for risk prediction, simplifying the modelling required. Further comprehensive, large-scale genome-wide interaction studies may identify novel interacting loci if the inherent logistic and computational challenges can be overcome.

Can selenium be a modifier of cancer risk in CHEK2 mutation carriers?

Selenium is an essential trace element for humans, playing an important role in various major metabolic pathways. Selenium helps to protect the body from the poisonous effects of heavy metals and other harmful substances. Medical studies have provided evidence of selenium supplementation in preventing certain cancers. Low and too high selenium (Se) status correlates with increased risk of e.g. lung, larynx, colorectal and prostate cancers. A higher level of selenium and supplementation with selenium has been shown to be associated with substantially reduced cancer mortality. Selenium exerts its biological roles through selenoproteins, which are involved in oxidoreductions, redox signalling, antioxidant defence, thyroid hormone metabolism and immune responses. Checkpoint kinase 2 (CHEK2) is an important signal transducer of cellular responses to DNA damage and acts as a tumour suppressor gene. Mutations in the CHEK2 gene have been shown to be associated with increased risks of several cancers. Four common mutations in CHEK2 gene (1100delC, IVS2+1G>A, del5395 and I157T) have been identified in the Polish population. Studies have provided evidence that CHEK2-truncating and/or missense mutations are associated with increased risk of breast, prostate, thyroid, colon and kidney cancers. The variability in penetrance and cancer expression in CHEK2 mutation carriers can probably be explained by the influence of other genetic or environmental factors. One of the possible candidates is Se, which together with genetic variations in selenoprotein genes may influence susceptibility to cancer risk.

Can selenium levels act as a marker of colorectal cancer risk?

BACKGROUND: Selenium has attracted attention because of its antioxidant properties. Antioxidants protects cells from damage. Certain breakdown products of selenium are believed to prevent tumor growth by enhancing the immune cell activity and suppressing the development of tumor blood vessels. In this observational study, selenium level was measured in a series of patients from Poland and Estonia to determine a correlation between levels of this microelement and colorectal cancer risk. METHODS: A total of 169 colorectal cancer patients and 169 healthy controls were enrolled in the study after obtaining their informed consent. Selenium level in the blood serum was measured using Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The statistical analysis was performed by Fisher's exact test. RESULTS: The threshold point of selenium level was 55 µg/l and 65 µg/l for Poland and Estonia respectively, for an increase in cancer risk. The lower levels of selenium were associated with greater risk of colorectal cancer. CONCLUSIONS: The result reveals a significant strong association between low selenium level and the colorectal cancer risk in both Estonian and Polish populations.