MTHFR polymorphisms, dietary folate intake and risks to breast cancer / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the relationship between dietary folate intake and genetic polymorphisms of 5, 10-methylenetetrahydrofolate reductase (MTHFR) with reference to breast cancer risk.</p><p><b>METHODS</b>A case-control study was conducted with 669 cases and 682 population-based controls in Jiangsu province of China. MTHFR C677T and A1298C genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. Dietary folate intake was assessed by using an 83-item food frequency questionnaire. Odds ratios (OR) were estimated with an unconditional logistic model.</p><p><b>RESULTS</b>The frequencies of MTHFR C677T C/C, C/T and T/T genotypes were 32.37% (202/624), 48.88% (305/624) and 18.75% (117/624) in cases and 37.66% (235/624), 48.24% (301/624) and 14. 10% (88/624) in controls, respectively. The difference in distribution was significant (chi2 = 6.616, P = 0.037), the T/T genotype being associated with an elevated OR for breast cancer (1.62, 95% CI: 1.14 -2.30). The frequencies of MTHFR A1298C A/A, A/C and C/C were 71.47% (446/624), 27.08% (169/624) and 1.44% (9/624) in cases and 68.11%(425/624), 30.13% (188/624) and 1.76% (11/624)in controls,with no significant differences found (chi2 = 1.716, P= 0.424). Folate intake of cases [(263.00 +/- 137.38) microg/d] was significantly lower than that of controls [(285.12 +/- 149.61) microg/d] (t = -2. 830, P =0.005). Compared with the lowest tertile (< or = 199.08 microg/d) of folate intake, the adjusted OR for breast cancer in the top tertile (> or = 315.11 microg/d) was 0.70 (95% CI: 0.53 -0.92). Among individuals with the MTHFR A1298C A/A genotype,adjusted OR for breast cancer were 0.89 (95% CI: 0.62 - 1.27) and 1.69 (95% CI: 1.20 - 2.36) for the second to the third tertile of folate intake compared with the highest folate intake group (X2trend = 11.372, P = 0.001).</p><p><b>CONCLUSION</b>The findings of the present study suggest that MTHFR genetic polymorphisms,and dietary intake of folate may modify susceptibility to breast cancer.</p>

Genetic polymorphisms of methylenetetrahydrofolate reductase and susceptibility to colorectal cancer.

OBJECTIVES: To study the relation between genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T or A1298C and the susceptibility of colorectal cancer. METHODS: We conducted a case-control study with 315 cases of colorectal cancer and 371 population-based controls in Jiangsu province, China. The epidemiological data were collected, and DNA of peripheral blood leukocytes was obtained from all of the subjects. MTHFR C677T and A1298C genotypes were detected by the PCR-RFLP method. RESULTS: (1) When men and women were assessed together, the frequencies of the MTHFR C677T and A1298 genotypes or their alleles were not significantly different between controls and colon cancer or rectal cancer cases. No significant relation was observed between MTHFR C677T or A1298C polymorphisms and colon or rectal cancer susceptibility. (2) Among males, individuals who had MTHFR C677T T/T genotype were at a significantly higher risk of developing colon cancer (age-, residence-, smoking-, alcohol drinking-, tea consumption-adjusted OR=2.15, 95%CI: 1.07-4.33) compared with those who had C677T C allele. Individuals who had C677T T/T and A1298C A/A genotypes were at an increased risk of developing colon cancer (adjusted OR=2.64, 95%CI: 1.20-5.81) compared with those with C677T C allele and A1298C A/A genotypes among males. On the contrary, individuals who had C677T T/T and A1298C A/A genotypes were at an decreased risk of developing rectal cancer (adjusted OR=0.47, 95%CI: 0.22-1.03). CONCLUSIONS: These results in the present study suggested that polymorphisms of the MTHFR C677T could influence susceptibility to colon or rectal cancer and that there was a coordinated effect between MTHFR A1298C A/A and C677T T/T genotypes among males.

Reproducibility of a semi-quantitative food frequency questionnaire in Chaoshan area, China.

OBJECTIVE: To examine reproducibility of assessed intake of foods and nutrients according to a semi-quantitative food frequency questionnaire (SQFFQ) in adult doctors and nurses residing in Chaoshan area of China. SUBJECTS: The SQFFQ was administered first in October to December of 2004 to 120 adult doctors and nurses living in Chaoshan area of China and was then re-administered to 102 three months later between January and March of 2005 (SQFFQ 1 and SQFFQ 2). METHODS: Reproducibility was evaluated in terms of consumption of 10 food groups and energy and 34 macro- and micro-nutrients based on the SQFFQ from the 102 doctors and nurses. RESULTS: For intake of foods, Pearsom's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.43 (eggs) - 0.84 - 0.90 (teas). Spearman's rank CCs with energy adjustment ranged from 0.77 (cereals) - 0.84 - 0.94 (milks). Kappa statistics with energy adjustment ranged from 0.53 (vegetables) - 0.63 - 0.82 (teas). For consumption of nutrients, Pearson's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.83 (docosahexaenoic acid and oryzanin) - 0.88 - 0.90 (linolenic acid, vitamin A, folic acid, vitamin E, calcium, sodium, selenium and magnesium). Spearman's rank CCs with energy adjustment ranged from 0.81 (oryzanin and vitamin C) - 0.86 - 0.90 (sodium). Kappa statistics with energy adjustment ranged from 0.49 (protein) - 0.60 - 0.77 (sodium). CONCLUSION: Substantially high reproducibility was observed; it is possible to use the tailored, relatively simple, but comprehensive, self-administered SQFFQ to facilitate assessment of the association between lifestyle and health/disease in large-scale epidemiological studies.

An epidemiological study of HBV, HCV and HTLV-I in Sherpas of Nepal.

An epidemiological study of hepatitis viruses type B (HBV) and type C (HCV) and human T-cell leukemia virus type I (HTLV-I) was carried out among 103 residents (male:female=61:42) regarded as Sherpas, at Lukla (Solukhumbu district), Nepal in 2004. Blood was drawn from apparently healthy volunteers at ages of 28.8+12.3 (range 15-66) years. HBsAg, HBsAb, HBcAb, and HCV Ab were measured by microparticle enzyme-immunoassay, and HTLV-I Ab was measured by particle agglutination. Prevalence of HBsAg(+), HBsAb(+), HBcAb(+), and HBsAb(+) or HBcAb(+) were 1.9% 22.3%, 24.3%, and 28.2%, respectively. For HCV Ab, only a borderline reaction was observed in one sample, and for HTLV-I Ab all samples were negative. Nucleotide sequencing of the PreS1, PreS2, and S genes revealed that HBV among Sherpas to be of the A' (or Aa) genotype, which is prevalent among Nepalese but rare in native Tibetans, suggesting transmission within Nepal rather than association with ancestors' migration from Tibet as the origin. This is the first report of Himalayan Sherpas' state of infection with HBV, HCV, and HTLV-I.

Comparison of lifestyle risk factors by family history for gastric, breast, lung and colorectal cancer.

To assess the theoretical impact of lifestyle of a cancer family history in first-degree relatives (CFH) and clarify interactions between CFH and lifestyle factors, hospital-based comparison and case-reference studies were conducted in Nagoya, Japan. Totals of 1988 gastric, 2455 breast, 1398 lung and 1352 colorectal cancer patients, as well as 50,706 non-cancer outpatients collected from 1988 to 1998, were checked for lifestyle factors, which included dietary and physical exercise habits, as well as smoking/drinking status. General lifestyle factors with non-cancer outpatients did not differ by the CFH status. Case-reference analyses showed that frequent intake of fruits, raw vegetables, carrots, pumpkin, cabbage and lettuce, as well as frequent physical exercise, were associated with decreased risk for all four sites of cancer, while habitual smoking increasing the risk of gastric, and more particularly, lung cancer. Interestingly, the study revealed the magnitude of odds ratios for the above lifestyle factors obtained from CFH positives to be similar to those from CFH negatives for these four sites of cancer. There were no significant interactions between CFH and any particular lifestyle factor. In conclusion, our results suggest no appreciable influence of CFH on lifestyle related risk factors for gastric, breast, lung, and colorectal cancer. Habitual smoking increased, while frequent physical exercise and raw vegetables intake decreased cancer risk, regardless of the CFH status.

Polymorphisms in thymidylate synthase and methylenetetrahydrofolate reductase genes and the susceptibility to esophageal and stomach cancer with smoking.

Thymidylate synthetase (TS) and methylenetetrahydrofolate reductase (MTHFR) are major enzymes in the metabolism of folates, involved in DNA 'breaks', instability and hypomethylation. To investigate the possible relations between the TS 3'-UTR and MTHFR C677T polymorphisms and environmental factors impacting on risk of esophageal and stomach cancers, we conducted a case-control study in a high incidence region of China for these cancers. We recruited 138 esophageal and 155 stomach cancer cases, and 223 controls. The TS 3' -UTR and MTHFR C677T genotypes were detected by RFLP assay, using PCR products. The frequency of the -6 bp homozygous TS 3' -UTR genotype was 37.7 % in controls, higher than in Caucasians, although the present distribution was not in Hardy-Weinberg equilibrium. Ever-smoking with the -6 bp/-6 bp TS genotype elevated the ORs (2.61, 1.24-5.49; 3.54, 1.60-7.82) for cases of esophageal and stomach cancers, respectively, when compared with never-smoking with the +6 bp/+6 bp and +6 bp/-6 bp genotypes. No combination between the TS and MTHFR genotypes gave increased ORs. The present results suggest that TS polymorphism may modify the risk of esophageal and stomach cancer with smoking, pointing to the necessity for further investigations with information on folate and methionine intake with a larger population.

Lack of HTLV-I carriers in the Sami, an ethnic group living in the Arctic area in Norway.

The Sami is an ethnic group with ill-defined genetic origins, living in the northern areas of the Scandinavian Peninsula and Russia. Distinct from other European populations in culture and language, they are generally deemed to be remote from the Caucasian lineage. In order to ascertain whether the Sami are genetically linked to Asiatic Mongoloids, we investigated serological markers of human T-cell leukemia virus type I (HTLV-I) infection. Particle agglutination tests for serum HTLV-I antibody were performed for 400 Sami living in Finnmark, the northernmost county of Norway, and in 380 Caucasians (or Norse) in the same region, using serum samples collected for the purpose of studying cardiovascular disease among Northland people in 1974-75. One sample from a Sami showed a tentatively positive reaction, and 4 sera from Sami and 4 from Norse individuals exhibited non-specific agglutination. However, none of the 9 sera showed a positive result in western blotting for HTLV-I proteins, namely, gp46, p53, p24, and p19. Since HTLV-I is distributed most prevalently among northern and southwestern Japanese in Asia and Andeans in South America, the absence of HTLV-I in the Sami might suggest their genetic remoteness from these ethnic groups.

A case-control study on the polymorphisms of methylenetetrahydrofolate reductase 1298A-->C and susceptibility of esophageal cancer / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between polymorphisms of methylenetetra-hydrofolate reductase gene 1298A-->C (MTHFR 1298A-->C) and its susceptibility of esophageal cancer (EC).</p><p><b>METHODS</b>We conducted a case-control study with 141 cases of EC and 228 population-based controls in Huaian city of Jiangsu province, China. Epidemiological data were collected, and DNA of peripheral blood leukocytes was obtained from all of the subjects. MTHFR genotypes were identified by polymerase chain reaction.</p><p><b>RESULTS</b>(1) The frequency of MTHFR 1298AA, AC and CC genotype were 63.8%, 34.0% and 2.1% in EC and 71.9%, 28.1% and 0.0% in controls, respectively (chi(2)(MH) = 6.69, P = 0.035). The frequency of the MTHFR 1298C allele was 0.19 for EC and 0.14 for controls. (2) Individuals having MTHFR 1298C allele and smoking habit were at a significantly higher risk of developing EC (adjusted OR = 3.48, 95% CI: 1.57 - 7.71) compared with those who having AA genotype but no smoking habit. Individuals having MTHFR 1298C allele and habit of frequent alcohol drinking were at an increased risk of developing EC (adjusted OR = 2.91, 95% CI: 1.20 - 7.08) compared with those with AA genotype and low consumption of alcohol. Individuals having MTHFR 1298C allele but no habit of tea drinking had a 3.52-fold (95% CI: 1.64 - 7.54) increased risk of developing EC compared with tea drinkers with AA genotype. As compared with subjects having AA genotype, low consumption of alcohol, no smoking habit but having habit of drinking tea, the individuals having 1298C allele, habits of frequent alcohol drinking, smoking but no habit of tea drinking had a 12.64-folds (95% CI: 1.39 - 114.65) increased risk of developing EC.</p><p><b>CONCLUSION</b>Results in the present study suggested that there was a coordinated effect between MTHFR 1298 genotypes and habits of smoking, alcohol drinking and tea consumption in the development of EC.</p>

Polymorphism of methylenetetrahydrofolate reductase and sensitivity of stomach cancer to fluoropyrimidine-based chemotherapy / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) C677T or A1298C and the response to fluoropyrimidine (5-FU)-based chemotherapy in advanced stomach cancer (SC).</p><p><b>METHODS</b>75 cases with advanced SC were analyzed. All patients were treated with 5-FU-based chemotherapy and DNA of peripheral blood leukocytes was obtained before therapy. MTHFR genotypes were detected by PCR-RFLP method.</p><p><b>RESULTS</b>(1) Of all the cases, the frequencies of MTHFR C677T C/C, C/T and T/T genotype were 32.0%, 44.0% and 24.0%, while the frequencies of MTHFR A1298C A/A, A/C and C/C genotype were 69.3%, 29.3% and 1.3%, respectively. The overal response rate to 5-FU-based chemotherapy was 29.3%. (2) The response rate to therapy among MTHFR C677T T/T genotype patients (83.3%) was significantly higher than the C677T C/T genotype (15.2%, chi(2) = 22.27, P = 0.000) or the C677T C/C genotype (8.3%, chi(2) = 23.44, P = 0.000). As compared with patients with C677T C allele, patients with C677T T/T genotype had a 7.64-fold sensitivity to 5-FU-based chemotherapy (adjusted for sex, age, prior adjuvant therapy and chemotherapy program, 95% CI: 3.14 - 18.62). The response rate to therapy among patients with MTHFR A1298C A/A genotype (36.5%) was significantly higher than patients with A1298C C allele (13.0%, chi(2) = 4.19, P = 0.041, adjusted OR = 3.75, 95% CI: 0.94 - 14.87). The response rate to therapy among patients with MTHFR C677T T/T and A1298C A/A genotypes (86.7%) was significantly higher than other groups of C677T and A1298C genotypes (15.0%, Fisher exact: P = 0.000, adjusted OR = 6.57, 95% CI: 2.8 - 15.6). (3) The incidence rates of nausea/vomiting in MTHFR C677T T/T, C/T or A1298C A/A genotypes were significantly higher than other genotypes, but the incidence rates of other treatment-related adverse reaction in MTHFR C677T or A1298C genotypes were not significantly different.</p><p><b>CONCLUSION</b>These results in the present study suggested that the polymorphisms of MTHFR were associated with clinical response to 5-FU-based chemotherapy, suggesting that MTHFR genotypes could identify advanced SC patients that would be responsive to 5-FU-based chemotherapy.</p>

Insulin, insulin-like growth factor-I and breast cancer risk in Japanese women.

To evaluate the effects of glucose metabolism related factors, such as insulin and insulin-like growth-factors (IGFs), on breast cancer development among Japanese women, we conducted a case-referent study comparing 187 women presenting with operable breast cancer and 190 women of the same age having no breast cancer. Odds ratios (OR) and 95% confidence intervals (95%CI) were determined by multiple logistic regression analysis. In the present study, no association in risk was observed with increasing levels of IGF-I or IGF binding protein-3 (IGFBP-3), before or after adjustment these factors. However, a suggestion of a positive association of an increased breast cancer risk was evident in postmenopausal women with elevated plasma insulin levels, particularly those with BMI>23.07. The OR for plasma insulin in the top tertile was 4.48 (95%CI:1.07-18.7) compared to the bottom tertile. For C-peptide, there was a similar positive association, with a corresponding OR of 2.28. In addition, we observed strong links between plasma insulin, C-peptide levels and estrogen receptor (ER) negative breast cancer, with ORs of 2.79(95%CI:1.09-7.16), and 2.52 (95%CI:0.91-6.97) respectively, for the top versus bottom tertiles. In conclusion, the present study suggested that plasma insulin level is a predictor of postmenopausal breast cancer in obese women and ER negative breast cancer. Additional studies are needed to clarify the role of glucose metabolism pathways in breast cancer development and interaction of IGF systems.

Interactions between lifestyle, methylanetetrahydrofolate reductase gene and polymorphisms in thymidylate synthase gene with risk of stomach cancer / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate interactions between lifestyle, methylanetetrahydrofolate reductase gene (MTHFR) and polymorphisms in the 3'-untranslated region (3'-UTR) of the thymidylate synthase gene (TS) with reference to development of stomach cancer (SC).</p><p><b>METHODS</b>We conducted a case-control study with 107 cases of SC and 200 population-based controls in Huaian city of Jiangsu province, China. TS genotypes were identified by polymerase chain reaction.</p><p><b>RESULTS</b>(1) The frequencies of TS genotypes (+6 bp/+6 bp, +6 bp/-6 bp and -6 bp/-6 bp) among the cases were 5.6%, 47.7% and 46.7% and among the controls were 9.0%, 54.0% and 37.0%, respectively. Individuals identified as -6 bp/-6 bp genotype had a slightly higher risk for SC than those individuals with +6 bp alleles (the crude OR = 1.49, 95% CI: 0.90 - 2.47; adjusted OR = 1.36, 95% CI: 1.00 - 1.78, P = 0.047). (2) Individuals having TS -6 bp/-6 bp genotype and having smoking habit were at a significantly higher risk of developing SC (adjusted OR = 2.79, 95% CI: 1.51 - 5.18) compared with those who had +6 bp alleles with no smoking habit. Individuals having TS -6 bp/-6 bp genotype and habit of frequent alcohol drinking were at an increased risk of developing SC (adjusted OR = 1.76, 95% CI: 1.07 - 2.90) compared with those with +6 bp alleles and low consumption of alcohol. As compared with individuals with +6 bp alleles and who had habit of tea drinking, individuals who had TS -6 bp/-6 bp genotype and but without habit of tea drinking had an increased risk of developing SC (adjusted OR = 2.34, 95% CI: 1.43 - 3.82). (3) Individuals with TS -6 bp/-6 bp genotype and with MTHFR T alleles had an increased risk of developing SC (adjusted OR = 2.67, 95% CI: 1.07 - 6.70) compared with those with +6 bp alleles and with MTHRF C/C genotype.</p><p><b>CONCLUSION</b>Results in the present study suggested that there was a combined effect between lifestyle, MTHFR C/T or T/T genotype and TS -6 bp/-6 bp genotype in the development of SC.</p>

Polymorphisms of methylenetetrahydrofolate reductase C677T and the risk of stomach cancer / 中华流行病学杂志

<p><b>OBJECTIVE</b>In order to study the relation between polymorphisms of methylenetetrahydrofolate reductase C677T (MTHFR) and susceptibility of stomach cancer (SC).</p><p><b>METHODS</b>We conducted a case-control study with 107 cases of SC and 200 population-based controls in Huaian city of Jiangsu province, China. The epidemiological data were collected, and DNA of peripheral blood leukocytes was obtained from all of the subjects. MTHFR genotypes were detected by PCR-RFLP method.</p><p><b>RESULTS</b>(1) The frequency of MTHFR variant genotypes (C/T + T/T) among the cases (79.4%) was significantly higher than the controls (68.5%) (P = 0.041 6); the crude OR for SC was 1.78 (95% CI: 0.99 - 3.22). After adjustment for sex and age, the OR for SC was 1.89 (95% CI: 1.08 - 3.32). (2) Subjects who had MTHFR variant genotypes and having smoking habit were at a significantly higher risk of developing SC (OR = 7.72, 95% CI: 2.23 - 26.79) compared with those who had wild-type homozygotes (C/C) genotype and no smoking habit. Individuals who had variant genotypes and who had habit of frequent alcohol drinking were at an increased risk of developing SC (OR = 3.08, 95% CI: 1.30 - 7.23) compared with those with C/C genotype and low consumption of alcohol. As compared with subjects with C/C genotype and low consumption of alcohol and no smoking habit, individuals who had variant genotypes and who had habits of frequent alcohol drinking and smoking had 12.96 (95% CI: 2.76 - 70.46) folds risk developing SC.</p><p><b>CONCLUSIONS</b>These results in the present study suggested that the polymorphisms of MTHFR C677T was associated with risk of developing SC, and there was a coordinated effect between MTHFR genotypes and habits of smoking and alcohol drinking in the development of SC.</p>