Ruiyun Jiang

The University of Arizona, Tucson, AZ, United States

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Publications (11)91.75 Total impact

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    ABSTRACT: Limited data exist regarding the actual risk of developing advanced adenomas and cancer after polypectomy or the factors that determine risk. We pooled individual data from 8 prospective studies comprising 9167 men and women aged 22 to 80 with previously resected colorectal adenomas to quantify their risk of developing subsequent advanced adenoma or cancer as well as identify factors associated with the development of advanced colorectal neoplasms during surveillance. During a median follow-up period of 47.2 months, advanced colorectal neoplasia was diagnosed in 1082 (11.8%) of the patients, 58 of whom (0.6%) had invasive cancer. Risk of a metachronous advanced adenoma was higher among patients with 5 or more baseline adenomas (24.1%; standard error, 2.2) and those with an adenoma 20 mm in size or greater (19.3%; standard error, 1.5). Risk factor patterns were similar for advanced adenomas and invasive cancer. In multivariate analyses, older age (P < .0001 for trend) and male sex (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.19-1.65) were associated significantly with an increased risk for metachronous advanced neoplasia, as were the number and size of prior adenomas (P < .0001 for trend), the presence of villous features (OR, 1.28; 95% CI, 1.07-1.52), and proximal location (OR, 1.68; 95% CI, 1.43-1.98). High-grade dysplasia was not associated independently with metachronous advanced neoplasia after adjustment for other adenoma characteristics. Occurrence of advanced colorectal neoplasia is common after polypectomy. Factors that are associated most strongly with risk of advanced neoplasia are patient age and the number and size of prior adenomas.
    Gastroenterology 12/2008; 136(3):832-41. · 12.82 Impact Factor
  • Gastroenterology 01/2008; 134(4). · 12.82 Impact Factor
  • Gastroenterology 01/2008; 134(4). · 12.82 Impact Factor
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    ABSTRACT: Obesity has been associated with increased risk for colorectal adenoma, although its role as a risk factor after polypectomy for recurrence is unclear. Therefore, we sought to evaluate the effect of anthropometric measures of obesity on adenoma after polypectomy. Subjects with baseline adenomas (n = 2465) and follow-up colonoscopy data were drawn from 2 randomized trials designed to prevent adenoma recurrence. Over a mean follow-up period of 3.1 years presence of a body mass index (BMI) > or = 30 kg/m2 was associated with a nonsignificant 17% increase in the odds for any adenoma recurrence among all subjects (odds ratio [OR], 1.17; 95% confidence interval [CI], 0.92-1.48). This result was confined to men (OR, 1.36; 95% CI, 1.01-1.83) and not observed for women (OR, 0.90; 95% CI, 0.60-1.33). Results for waist circumference did not reach statistical significance, although trends were similar to those for BMI. Analyses of the effects of obesity on more clinically significant lesions demonstrated that high BMI was a slightly stronger risk factor for advanced adenoma recurrences in men (OR, 1.62; 95% CI, 1.04-2.53) when compared with non-advanced lesions (OR, 1.26; 95% CI, 0.91-1.75). In addition, we observed an association for obesity and odds of adenoma recurrence among participants reporting a family history of colorectal cancer (OR, 2.25; 95% CI, 1.32-3.84) but not for those without (OR, 1.00; 95% CI, 0.77 to 1.31; P(int) = P = .008). Our results support obesity as a risk factor for subsequent short-interval (mean follow-up time 3.1 years) development of colorectal adenomas, particularly among men and persons with a family history of colorectal cancer. Furthermore, obesity in men appears to be strongly associated with the development of clinically advanced lesions.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 08/2007; 5(8):982-90. · 5.64 Impact Factor
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    ABSTRACT: Methylenetetrahydrofolate reductase (MTHFR) is involved in intracellular folate homeostasis and metabolism. We assessed 2 polymorphisms in the MTHFR gene (C677T and A1298C) in relation to colorectal adenoma recurrence and conducted analyses to investigate their joint effects with plasma and dietary markers of folate status. We prospectively analyzed data from 1598 individuals genotyped for the C677T polymorphism and 1583 with data on A1298C. Among nonusers of multivitamin supplements, compared with wild-type carriage, higher odds of recurrence were observed for those with the 677 TT variant (odds ratio [OR], 1.66; 95% confidence interval [CI], 1.04-2.63) and a nonsignificant increase was observed among those with the 1298 CC variant (OR, 1.50; 95% CI, 0.93-2.40). Diplotype analyses among nonusers of multivitamins showed that individuals who carry the MTHFR 677TT_1298AA or 677CC_1298CC combination were significantly more likely to have a recurrence compared with those with the double wild-type (OR, 2.05 for TT_AA and 1.85 for CC_CC). Higher odds of recurrence were observed among participants with low folate intake or plasma folate and the 677 TT or 1298 CC variants compared with those with lower levels and the wild-type or heterozygous genotypes. Stronger associations were shown for the combination of high homocysteine and the 677 TT variant (OR, 2.29; 95% CI, 1.00-5.26) but not the 1298 CC variant (OR, 1.09; 95% CI, 0.39-3.01). We propose that the effect of the MTHFR genotypes on increasing risk of adenoma recurrence in the presence of a low folate status is through their increase in homocysteine concentrations, which in turn could result in DNA hypomethylation via pathways involving S-adenosylhomocysteine.
    Gastroenterology 12/2006; 131(6):1706-16. · 12.82 Impact Factor
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    ABSTRACT: In 1996, the US Food and Drug Administration mandated the fortification of grain products with folic acid, a nutrient that has been associated with lower risk of colorectal neoplasia. We assessed the relation of plasma folate and homocysteine and colorectal adenoma recurrence separately in 2 studies: the first involved an intervention of a cereal supplement that contained folic acid, wheat bran fiber (WBF), and the second was conducted primarily during postfortification of the food supply using ursodeoxycholic acid (UDCA). Analyses were stratified for multivitamin use. Results show that plasma folate and homocysteine concentrations were associated with adenoma recurrence among nonusers of multivitamins only. Among nonmultivitamin users, the odds ratio [OR] (95% confidence interval [CI]) for those in the highest versus the lowest folate quartile was 0.65 (0.40-1.06) for the WBF study and 0.56 (0.31-1.02) for the UDCA; likewise, individuals in the highest versus the lowest quartile of homocysteine had higher odds of adenoma recurrence, in both the WBF (OR = 2.25; 95% CI = 1.38-3.66) and UDCA (OR = 1.93; 95% CI = 1.07-3.49) populations. Analyses comparing multivitamin users to different plasma folate concentrations among nonusers show that odds of recurrence for supplement users was lower only when compared to nonusers who had lower concentrations. Our results show that higher plasma folate or lower homocysteine levels are associated with lower odds of recurrence among nonusers of multivitamins in both studies. Our finding, suggesting that multivitamins or supplemental folate only benefit individuals with lower plasma folate concentrations, should be taken into consideration when designing and interpreting results of intervention studies.
    International Journal of Cancer 10/2006; 119(6):1440-6. · 6.20 Impact Factor
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    ABSTRACT: In colorectal tumorigenesis, Ki-ras proto-oncogene mutation often occurs early in the adenoma-adenocarcinoma sequence, whereas mutation of the p53 gene is associated with late progression to carcinoma. We evaluated the relationship of demographic and clinicopathologic characteristics to Ki-ras mutation and p53 gene product overexpression in 1,093 baseline sporadic colorectal adenomas from 926 individuals enrolled in a phase III recurrence prevention trial. Ki-ras mutation was found in 14.7% of individuals and p53 overexpression was found in 7.0% of those tested. Multivariate analysis found older age, rectal location, and villous histology to be independently associated with Ki-ras mutation. Individuals with an advanced adenoma (>or=1 cm or high-grade dysplasia or villous histology) had a 4-fold higher likelihood of Ki-ras mutation [odds ratios (OR), 3.96; 95% confidence intervals (CI), 2.54-6.18]. Ki-ras mutations in codon 12 and of the G-to-A transition type were more frequent in older individuals, whereas G-to-T transversion was more frequent in rectal adenomas than in the colon. Multivariate analysis showed that previous history of a polyp (P = 0.03) was inversely associated with p53 overexpression. Large adenoma size (>or=1 cm), high-grade dysplasia, and villous histology were independently associated with p53 overexpression, with the strongest association for advanced adenomas (OR, 7.20; 95% CI, 3.01-17.22). Individuals with a Ki-ras mutated adenoma were more likely to overexpress p53 (OR, 2.46; 95% CI, 1.36-4.46), and 94.8% of adenomas with both alterations were classified as advanced (P <or= 0.0001). Our large cross-sectional study supports the role of both Ki-ras and p53 in the progression of adenomas and shows that their molecular pathogenesis differs by anatomic location, age, and mucosal predisposition as evidenced by previous history of a polyp.
    Cancer Epidemiology Biomarkers &amp Prevention 08/2006; 15(8):1443-50. · 4.56 Impact Factor
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    ABSTRACT: Evidence for an association between dietary fiber and colorectal neoplasia has been equivocal, and some data suggest that there may be sex differences in response to fiber. We sought to determine whether fiber affects colorectal adenoma recurrence differently in men and women by combining the study populations of 2 large clinical intervention trials: the Wheat Bran Fiber Trial and the Polyp Prevention Trial. Data from 3209 participants combined from 2 trials were analyzed with logistic regression models to examine the effect of a dietary intervention on colorectal adenoma recurrence in the pooled population as a whole and by sex. The adjusted odds ratio for adenoma recurrence for those in the intervention group of either the Wheat Bran Fiber Trial or the Polyp Prevention Trial was 0.91 (95% CI: 0.78, 1.06). For men, the intervention was associated with statistically significantly reduced odds of recurrence with an odds ratio of 0.81 (95% CI: 0.67, 0.98); for women, no significant association was observed. Using a likelihood-ratio test, we found a statistically significant interaction between intervention group and sex (P = 0.03). The results of the current analyses indicate that men may experience more benefit from dietary fiber than do women and may help to explain some of the discrepant results reported in the literature.
    American Journal of Clinical Nutrition 02/2006; 83(2):343-9. · 6.50 Impact Factor
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    ABSTRACT: Secondary analyses of data from a large randomized clinical trial have suggested that intake of the trace element selenium reduces risk of colorectal neoplasia, but epidemiologic studies have not shown a consistent protective association. We conducted a combined analysis of data from three randomized trials--the Wheat Bran Fiber Trial, the Polyp Prevention Trial, and the Polyp Prevention Study--which tested the effects of various nutritional interventions for colorectal adenoma prevention among participants who recently had an adenoma removed during colonoscopy. Selenium concentrations were measured from blood specimens from a total of 1763 trial participants, and quartiles of baseline selenium were established from the pooled data. To estimate the association between baseline selenium and colorectal adenoma risk, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression modeling. All statistical tests were two-sided. Individual study results among participants whose blood selenium concentrations were in the highest versus the lowest quartile varied in magnitude (Polyp Prevention Trial: OR = 0.67, 95% CI = 0.43 to 1.05; P(trend) = .21; Wheat Bran Fiber Trial: OR = 0.66, 95% CI = 0.40 to 1.10; P(trend) = .13, and Polyp Prevention Study: OR = 0.57, 95% CI = 0.34 to 0.95, P(trend) = .04). Analyses of the pooled data showed that individuals whose blood selenium values were in the highest quartile (median = 150 ng/mL) had statistically significantly lower odds of developing a new adenoma compared with those in the lowest quartile (OR = 0.66, 95% CI = 0.50 to 0.87; P(trend) = .006). The inverse association between higher blood selenium concentration and adenoma risk supports previous findings indicating that higher selenium status may be related to decreased risk of colorectal cancer.
    CancerSpectrum Knowledge Environment 12/2004; 96(22):1669-75. · 14.07 Impact Factor
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    ABSTRACT: Exposure to tobacco products is readily assessed through self- or interview-administered questionnaires. Degree of misreporting among participants in chemoprevention trials is unknown. We assessed the level of discrepancy between self-reported smoking exposure and plasma cotinine among participants in a chemoprevention trial. Analyses were conducted among 824 men and women who participated in a dietary trial of adenoma recurrence. Smoking exposure was ascertained through self-administered questionnaires at three time-points. Plasma cotinine was measured by gas chromatography among 283 never, 446 former and 95 current self-reported smokers. Sensitivity and specificity were assessed using various plasma cotinine cut-points. Degree of misclassification for self-reported current smokers was minor (0-3%), regardless of cotinine cut-point used. Using a cut-point of 20 ng/ml, which takes into account exposure to environmental tobacco smoke among nonsmokers, sensitivity and specificity were 98.9% and 80.2%, respectively. These data indicate that degree of misreport for current smokers is extremely low; however, approximately 20% of self-reported never smokers misreport their exposure, suggesting that validation of self-report is needed for these individuals.
    Preventive Medicine 05/2004; 38(4):492-7. · 3.50 Impact Factor
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    ABSTRACT: Background: Secondary analyses of data from a large ran- domized clinical trial have suggested that intake of the trace element selenium reduces risk of colorectal neoplasia, but epidemiologic studies have not shown a consistent protective association. Methods: We conducted a combined analysis of data from three randomized trials—the Wheat Bran Fiber Trial, the Polyp Prevention Trial, and the Polyp Prevention Study—which tested the effects of various nutritional inter- ventions for colorectal adenoma prevention among partici- pants who recently had an adenoma removed during colonoscopy. Selenium concentrations were measured from blood specimens from a total of 1763 trial participants, and quartiles of baseline selenium were established from the pooled data. To estimate the association between baseline selenium and colorectal adenoma risk, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression modeling. All statistical tests were two-sided. Results: Individual study results among participants whose blood selenium concentrations were in the highest versus the lowest quartile varied in magnitude (Polyp Prevention Trial: OR 0.67, 95% CI 0.43 to 1.05; Ptrend .21; Wheat Bran Fiber Trial: OR 0.66, 95% CI 0.40 to 1.10; Ptrend .13, and Polyp Prevention Study: OR 0.57, 95% CI 0.34 to 0.95, Ptrend .04). Analyses of the pooled data showed that individuals whose blood selenium values were in the highest quartile (median 150 ng/mL) had statistically significantly lower odds of developing a new adenoma compared with those in the lowest quartile (OR 0.66, 95% CI 0.50 to 0.87; Ptrend .006). Conclusions: The inverse association between higher blood selenium concentration and adenoma risk supports previous findings indicating that higher sele- nium status may be related to decreased risk of colorectal cancer. (J Natl Cancer Inst 2004;96:1669 -75) protective effect of selenium intake has come from a large, randomized, double-blind, placebo-controlled trial that involved supplementation with 200 g of selenium per day or placebo for prevention of nonmelanoma skin cancer (7). Although selenium supplementation did not reduce skin cancer risk in this trial, secondary analyses of the data showed a statistically significant 58% (95% CI 0.18 to 0.95) reduction in colorectal cancer incidence among participants randomly assigned to the selenium supplement group (7) (it should be noted that the results were attenuated and no longer statistically significant after additional years of follow-up) (8). Several epidemiologic investigations of the relationship between selenium and colon and rectal neoplasia have shown an inverse association (9 -15), although others have reported null results (16,17). However, many of these epidemi- ologic studies involved relatively small numbers of participants and were thus unable to provide a precise estimate of a reduction in risk. Pooling data from multiple studies is one epidemiologic tool for investigating important public health concerns (18). The availability of blood selenium data from three completed clinical trials of colorectal adenoma—the Wheat Bran Fiber Trial, the Polyp Prevention Trial, and the Polyp Prevention Study—pro- vided an opportunity to assess the relationship between selenium concentrations and adenoma recurrence. Each of the three trials was conducted to assess the effect of a dietary nutrient or intervention on the risk of developing a new colorectal adenoma among participants who recently had an adenoma removed dur- ing colonoscopy. The populations of the three trials were similar clinically, and colorectal adenoma endpoints were assessed care- fully by follow-up colonoscopy. In this study, individual data