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- Harrison, Tabitha A., et al.
(författare)
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Genome-wide association study by colorectal carcinoma subtype
- 2018
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Ingår i: Cancer Research. - : American Association for Cancer Research. - 0008-5472 .- 1538-7445. ; 78:13
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Over 50 genetic variants have been associated with colorectal cancer (CRC) risk through genome-wide association studies (GWAS), yet these variants represent only a fraction of the total estimated heritability. CRC is a heterogenous disease with diverse tumor etiology. Assessing genetic risk in molecular subtypes may help to identify novel loci and characterize genetic risk among tumor subtypes. We used microsatellite instability (MSI), an established CRC classifier with etiological and therapeutic relevance, to define CRC subtypes for GWAS analyses. We conducted a case-case analysis to estimate odds ratios (OR) and 95% confidence intervals (CI) for association of genome-wide variants with microsatellite stable (MSS) versus unstable (MSI) carcinomas. We ran an inverse-variance weighted fixed-effects meta-analysis across GWAS in a discovery set of 4,163 population-based CRC cases with harmonized microsatellite instability (MSI) marker and imputed genotype data. For each analysis, we used log-additive logistic regression, adjusting for age, sex, and principal components to account for population substructure. We then followed up with replication of 102 SNPs that reached p-values less than 5x10-6 in 1,698 cases. A total of 845 (20.3%) cancer cases were microsatellite unstable in the discovery population and 174 (10.2%) were unstable in the replication population. No variants reached the genome-wide significance level of 5x10-8 in the discovery set. However, we identified two variants that reached a Bonferroni corrected p-value of 4.0x10-4 in the replication set. This included one variant in MLH1 (Replication: OR=1.74, 95% CI=1.53-1.98, p=1.63x10-5; Discovery+Replication: OR=1.45, 95% CI=1.37-1.54, p=9.76x10-11) and one variant in LOC105377645 (Replication: OR=1.70, 95% CI=1.49-1.94, p=5.13x10-5; Discovery+Replication: OR=1.45, 95% CI=1.37-1.54, p=9.76 x 10-11). The MLH1 gene is a DNA mismatch repair gene implicated in Lynch Syndrome, the hallmark of which is microsatellite instability. This is the first genome-wide scan to identify a common variant in MLH1 that is associated with CRC. This variant (minor allele frequency, MAF = 23% in this all European ancestry population) is located in the 5'-untranslated region of MLH1 and is thought to act as a long-range regulator of DCLK3, a potential tumor driver gene. The second variant, located in LOC105377645 with an MAF of 22%, is in an uncharacterized region of the genome and has not previously been implicated in cancer development. These findings suggest that accounting for molecular heterogeneity is important for discovery and characterization of genetic variants associated with CRC risk. We plan to run polytomous regression analyses, increase our sample size, and further investigate CRC subtypes by CIMP, BRAF mutation, KRAS mutation status.
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| 2. |
- Simon, Tracey G., et al.
(författare)
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Association Between Aspirin Use and Risk of Hepatocellular Carcinoma
- 2018
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Ingår i: JAMA Oncology. - : American Medical Association. - 2374-2437 .- 2374-2445. ; 4:12, s. 1683-1690
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE: Prospective data on the risk of hepatocellular carcinoma (HCC) according to dose and duration of aspirin therapy are limited.OBJECTIVE: To examine the potential benefits of aspirin use for primary HCC prevention at a range of doses and durations of use within 2 prospective, nationwide populations.DESIGN, SETTING, AND PARTICIPANTS: Pooled analysis of 2 prospective US cohort studies: the Nurses' Health Study and the Health Professionals Follow-up Study. Data were accessed from November 1, 2017, through March 7, 2018. A total of 133 371 health care professionals who reported data on aspirin use, frequency, dosage, and duration of use biennially since 1980 in women and 1986 in men were included. Individuals with a cancer diagnosis at baseline (except nonmelanoma skin cancer) were excluded.MAIN OUTCOMES AND MEASURES: Cox proportional hazards regression modelswere used to calculate multivariable adjusted hazard ratios (HRs) and 95% CIs for HCC.RESULTS: Of the 133 371 participants, 87 507 were women and 45 864 were men; in 1996, the median time of follow-up, the mean (SD) age was 62 (8) years for women and 64 (8) years for men. Over more than 26 years of follow-up encompassing 4 232 188 person-years, 108 incident HCC cases (65 women, 43 men) were documented. Compared with nonregular use, regular aspirin use (>= 2 standard-dose [325-mg] tablets per week) was associated with reduced HCC risk (adjusted HR, 0.51; 95% CI, 0.34-0.77). This benefit appeared to be dose related: compared with nonuse, the multivariable-adjusted HR for HCC was 0.87 (95% CI, 0.51-1.48) for up to 1.5 standard-dose tablets per week, 0.51 (95% CI, 0.30-0.86) for more than 1.5 to 5 tablets per week, and 0.49 (95% CI, 0.28-0.96) for more than 5 tablets per week (P for trend =.006). Significantly lower HCC risk was observed with increasing duration (P for trend =.03); this decrease was apparent with use of 1.5 or more standard-dose aspirin tablets per week for 5 or more years (adjusted HR, 0.41; 95% CI, 0.21-0.77). In contrast, use of nonaspirin nonsteroidal anti-inflammatory drugs was not significantly associated with HCC risk (adjusted HR, 1.09; 95% CI, 0.78-1.51). CONCLUSIONS AND RELEVANCE: This study suggests that regular, long-term aspirin use is associated with a dose-dependent reduction in HCC risk, which is apparent after 5 or more years of use. Similar associations were not found with nonaspirin NSAIDs. Further research appears to be needed to clarify whether aspirin use represents a feasible strategy for primary prevention against HCC.
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| 3. |
- Burke, Kristin E., et al.
(författare)
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Identification of Menopausal and Reproductive Risk Factors for Microscopic Colitis-Results From the Nurses' Health Study
- 2018
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Ingår i: Gastroenterology. - : Saunders Elsevier. - 0016-5085 .- 1528-0012. ; 155:6, s. 1764-1775
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Microscopic colitis is a chronic inflammatory disorder of the colon primarily affecting postmenopausal women. However, the relation between hormonal determinants, including reproductive and menopausal factors, and risk of microscopic colitis has yet to be characterized.METHODS: We collected data from 227,766 women who participated in the Nurses' Health Study (NHS) and the NHSII without a baseline history of microscopic colitis. Reproductive and menopausal factors were assessed in 1988 in the NHS and 1989 in the NHSII and updated biennially. Cases of microscopic colitis were confirmed through review of pathology records. We used Cox proportional hazards modeling to estimate hazard ratios and 95% confidence intervals.RESULTS: Through 2014 in the NHS and 2015 in the NHSII, we confirmed 275 incident cases of microscopic colitis over 5,147,282 person-years. Compared with never use, current use of menopausal hormone therapy was associated with increased risk of microscopic colitis (multivariable-adjusted hazard ratio 2.64; 95% confidence interval 1.78-3.90). The risk increased with longer duration of use (P for trend < .0001) and decreased after discontinuation (P for trend = .002). The association did not differ according to disease subtype (P for heterogeneity = .34). Similarly, ever use of oral contraceptives was associated with increased risk of microscopic colitis (multivariable-adjusted hazard ratio 1.57; 95% confidence interval 1.16-2.13). There were no associations between age at menarche, parity, age at first birth, age at menopause, or menopause type and incident microscopic colitis.CONCLUSIONS: In 2 large prospective cohort studies, we observed an association between exogenous hormone use and incident microscopic colitis. Further studies are needed to determine the mechanisms underlying these associations.
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| 4. |
- Burke, Kristin E., et al.
(författare)
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Smoking is Associated with an Increased Risk of Microscopic Colitis : Results From Two Large Prospective Cohort Studies of US Women
- 2018
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Ingår i: Journal of Crohn's & Colitis. - : Crohn's & Colitis Foundation of Canada. - 1873-9946 .- 1876-4479. ; 12:5, s. 559-567
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Long-term data on the influence of smoking on risk of microscopic colitis are limited. We therefore sought to examine and characterize the association between smoking and risk of incident microscopic colitis in two large prospective cohorts of women.Methods: We conducted a prospective study of 231,015 women enrolled in the Nurses' Health Study (NHS) and NHSII. Information regarding smoking, other lifestyle factors, and medications were collected biennially from 1976 to 2012 in NHS and 1989 to 2013 in NHSII. Incident cases of microscopic colitis were confirmed through physician medical record review. We used Cox proportional hazards modeling to examine the association between smoking and risk of microscopic colitis.Results: We documented 166 incident cases of microscopic colitis over 6,122,779 person-years of follow up. Compared to non-smokers, the multivariable-adjusted hazard ratio (HR) for microscopic colitis was 2.52 (95% CI 1.59 - 4.00) amongst current smokers and 1.54 (95% CI 1.09 - 2.17) amongst past smokers. The risk increased with higher pack-years of smoking (Ptrend = 0.001) and diminished following smoking cessation (Ptrend = 0.017). Current smoking appeared to be more strongly associated with risk of collagenous colitis (3.68; 95% CI 1.94 - 6.97) than lymphocytic colitis (HR 1.71; 95% CI 0.83 - 3.53).Conclusion: In two large prospective cohort studies, we observed an association between current smoking and risk of microscopic colitis. Risk of microscopic colitis appeared to increase with higher pack-years and diminish following smoking cessation. Future studies focused on characterizing the biologic mechanisms underlying these associations are warranted.
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