Re: Population-based, case-control study of HER2 genetic polymorphism and breast cancer risk.
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Breast Neoplasms↗
Biomedical subjects
Nilanjan Chatterjee
Publications and source records attributed to Nilanjan Chatterjee.
Dietary fibre and colorectal adenoma in a colorectal cancer early detection programme.
BACKGROUND: Although dietary fibre has been reported to have no association with colorectal adenoma and cancer, in some studies this topic remains controversial. METHODS: We used a 137-item food frequency questionnaire to assess the relation of fibre intake and frequency of colorectal adenoma. The study was done within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a randomised controlled trial designed to investigate methods for early detection of cancer. In our analysis, we compared fibre intake of 33971 participants who were sigmoidoscopy-negative for polyps, with 3591 cases with at least one histologically verified adenoma in the distal large bowel (ie, descending colon, sigmoid colon, or rectum). Odds ratios were estimated by logistic regression analysis. FINDINGS: High intakes of dietary fibre were associated with a lower risk of colorectal adenoma, after adjustment for potential dietary and non-dietary risk factors. Participants in the highest quintile of dietary fibre intake had a 27% (95% CI 14-38, p(trend)=0.002) lower risk of adenoma than those in the lowest quintile. The inverse association was strongest for fibre from grains and cereals and from fruits. Risks were similar for advanced and non-advanced adenoma. Risk of rectal adenoma was not significantly associated with fibre intake. INTERPRETATION: Dietary fibre, particularly from grains, cereals, and fruits, was associated with decreased risk of distal colon adenoma.
Adenoma↗
Adjustment for competing risk in kin-cohort estimation.
Kin-cohort design can be used to study the effect of a genetic mutation on the risk of multiple events, using the same study. In this design, the outcome data consist of the event history of the relatives of a sample of genotyped subjects. Existing methods for kin-cohort estimation allow estimation of the risk of one event at a time with the assumption that the censoring events are unrelated to the genetic mutation under study. These methods, however, may produce biased estimates of risk when multiple events are related to the genetic mutation, and follow-up of some of the events may be censored by the onset of other events. Using a competing risk framework to address this problem, we show that cause-specific hazard functions for carriers and noncarriers are identifiable from kin-cohort data. For estimation, we propose an extension of a composite-likelihood approach we described previously. We illustrate the use of the proposed method for estimation of the risk of ovarian cancer from BRCA1/2 mutations in the absence of breast cancer, based on data from the Washington Ashkenazi Kin-Cohort Study. We also evaluate the performance of the proposed estimation method, based on simulated data that were generated following the setup of the Washington Ashkenazi Study.
Age Factors↗
Apportioning causes, targeting populations and predicting risks: population attributable fractions.
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Asbestos↗
The HER2 I655V polymorphism and breast cancer risk in Ashkenazim.
SUMMARY: BACKGROUND Over-expression of the human epidermal growth factor receptor 2 (Her2) protooncogene is associated with poor prognosis among female patients with breast cancer. A polymorphism in the HER2 gene (I655V) has been associated with an elevated risk of breast cancer in some ethnic groups. METHODS Subjects from a community-based study of 5318 Ashkenazim from the Washington, DC area were selected for analysis of the I655V HER2 germline polymorphism. We estimated age-specific breast cancer risk from HER2 I655V based on the family history data, using the female first-degree relatives of the study participants and a novel extension of the kin cohort method. RESULTS The estimated cumulative risk of breast cancer to age 70 was approximately 30% higher among HER2 I655V carriers than noncarriers (RR = 1.33; 95% confidence interval [CI] = 1.03-1.83). The effect of the allele seems stronger at younger ages (among women younger than 50 years, RR = 2.11; CI = 1.39-3.28) and especially among younger women with a family history of breast cancer (RR = 8.9; CI = 1.9-19.7). Increased risk of breast cancer associated with the I655V allele was also observed among BRCA1/2 mutation carriers, although these results are based on small numbers. CONCLUSION These analyses suggest that the HER2 valine allele might be associated with increased risk of breast cancer, especially in young women and in women with a family history of the disease.
Adult↗
Urinary mutagenicity and colorectal adenoma risk.
We investigated urinary mutagenicity and colorectal adenoma risk in a clinic-based, case-control study of currently nonsmoking cases (n = 143) and controls (n = 156). Urinary organics were extracted by C18/methanol from 12-h overnight urine samples, and mutagenicity was determined in Salmonella YG1024 +S9 (Ames test). Adenoma risk was 2.4-fold higher in subjects in the highest versus the lowest quintile of urinary mutagenicity (95% confidence interval = 1.1-5.1). Combining urinary mutagenicity with intake of meat-derived mutagenicity (from our earlier analysis) resulted in a 5.6-fold increase in adenoma risk (95% confidence interval = 2.2-13.9, comparing the highest with the lowest quintile). In our study population, diet may have contributed to mutagenic exposure, which was positively associated with colorectal adenoma risk.
Adenoma↗
Estrogen receptor breast cancer phenotypes in the Surveillance, Epidemiology, and End Results database.
BACKGROUND: Researchers question whether estrogen receptor alpha-negative (ERN) and -positive (ERP) represent different stages of one disease or different breast cancer types. OBJECTIVE: To further examine ERalpha phenotypes, we stratified incident tumor characteristics in the Surveillance, Epidemiology, and End Results (SEER) Database (n = 82,488) by ERN and ERP. METHODS: Study variables included black-white race, age-at-diagnosis, and standard incident tumor characteristics. These characteristics were arbitrarily dichotomized into good versus poor prognostic factor groups, for example, good (tumor size < or = 2.0 cm, negative axillary lymph nodes, and good histologic grade) versus poor (tumor size > 2.0 cm, positive nodes, and poor grade). Age frequency density plots were generated from the corresponding age-at-diagnosis frequency histograms. Average annual age-specific incidence rates (or risks) were adjusted to the 1970 United States standard female population. RESULTS: Age frequency density plots demonstrated bimodal premenopausal and postmenopausal breast cancer populations. ERN was correlated with premenopausal disease, black race, and poor prognostic factor groups, whereas ERP was associated with postmenopausal disease, white race, and favorable tumor characteristics. ERN rates increased premenopausally and then flattened to a nearly constant level after 50 years of age. ERP risk rose for most of a woman's lifetime with the greatest risk occurring between 75 and 79 years. CONCLUSIONS: ERalpha exhibited bimodal age frequency distribution with a dichotomous pattern for age-specific rates, racial, and prognostic factor profiles. Menopause had a greater effect on ERN than ERP. Possible implications for breast carcinogenesis and cancer prevention are discussed in the text.
Adult↗
Can cervicography be improved? An evaluation with arbitrated cervicography interpretations.
OBJECTIVE: The purpose of this study was to estimate the optimal performance of cervicography. We compared an arbitrated cervigram classification with an arbitrated referent diagnosis of cervical neoplasia. STUDY DESIGN: From an initial group of 8460 women, a stratified sample of cervigrams from 3645 women and histologic information from 414 women underwent arbitration. Interobserver agreement was assessed for cervicography and the referent diagnosis. Sensitivity, specificity, and predictive values were estimated for initial and arbitrated cervicography results, compared with the initial and arbitrated referent diagnoses. RESULTS: For the detection of arbitrated high-grade lesions or cancer, arbitrated cervicography yielded an overall sensitivity of 63.9% and a specificity of 93.7%. Significantly higher sensitivity was associated with younger age and age-related visual characteristics. CONCLUSION: Optimization of the cervigram classification improved performance over a single interpretation in this population but suggested the limits of static visual screening.
Colposcopy↗
Breast cancer risk in Ashkenazi BRCA1/2 mutation carriers: effects of reproductive history.
BACKGROUND: Younger age at first birth and greater parity generally reduce the risk of developing breast cancer, but whether this reduced risk holds in women with a mutation in the BRCA1 or BRCA2 gene is unknown. METHODS: In a Washington DC community-based study conducted in 1996, we tested 5318 Ashkenazi Jews for three BRCA1/2 founder mutations and identified 120 mutation carriers. Applying an extension of the "kin-cohort" analysis, we compared the effects of reproduction on breast cancer risk in carriers and noncarriers. We also used a case-case analysis among 288 participants who had been diagnosed with breast cancer. RESULTS: In noncarriers, the estimated relative risk (RR) of breast cancer rose 5% with each 5-year increment in age at first birth (RR = 1.05; 95% confidence interval [CI] = 0.97-1.15). By contrast, the estimated risk in mutation carriers fell with each 5-year increment in age (RR = 0.65; 95% CI = 0.37-1.16). Among the 288 participants who were breast cancer survivors themselves, the comparison of carriers with noncarriers also showed no protection associated with early birth in the presence of a mutation in BRCA1 or BRCA2. CONCLUSIONS: It is not yet clear whether the recognized breast cancer risk factors operate in the same way in women who carry a mutation in the BRCA1 or BRCA2 genes.
Adult↗
Validation studies: bias, efficiency, and exposure assessment.
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Bias↗
Analysis of survival data from case-control family studies.
In case-control family studies with survival endpoint, age of onset of diseases can be used to assess the familial aggregation of the disease and the relationship between the disease and genetic or environmental risk factors. Because of the retrospective nature of the case--control study, methods for analyzing prospectively collected correlated failure time data do not apply directly. In this article, we propose a semiparametric quasi-partial-likelihood approach to simultaneously estimate the effect of covariates on the age of onset and the association of ages of onset among family members that does not require specification of the baseline marginal distribution. We conducted a simulation study to evaluate the performance of the proposed approach and compare it with the existing semiparametric ones. Simulation results demonstrate that the proposed approach has better performance in terms of consistency and efficiency. We illustrate the methodology using a subset of data from the Washington Ashkenazi Study.
Age of Onset↗
Joint effect of genes and environment distorted by selection biases: implications for hospital-based case-control studies.
The hospital-based case-control design enhances the response rates in studies that require the collection of biological samples from all of the participants. There are simple, established criteria for selecting controls so as to estimate the effect of a single factor without bias, but the analogous requirements for assessing an interaction are less clear. We derive these conditions by calculating the potential bias from selecting controls who were admitted for treatment of diseases related to either or both of the exposures of interest, designated as a gene variant (G) and an environmental agent (E). There is no bias in the estimate of the effect of E when G is associated with the control condition, whether causally or because of confounding. There is no bias in estimating multiplicative interaction between G and E for the disease of interest when there is no multiplicative G-E interaction for the control disease, even when the control condition is caused by G or E; if a mixture of several control diseases are used, however, the absence of G-E interaction in each individual disease does not ensure a lack of overall bias when controls are pooled. Hospital control designs are much less robust for assessing additive interaction. We conclude that the ideal control disease in a hospital-based study of gene-environment interaction is not caused by either G or E and that choosing controls from several conditions to act as a combined control group is a useful strategy. This formulation extends to the general problem of distortion of joint effects from selection biases or confounding.
Case-Control Studies↗
NAT2 slow acetylation, GSTM1 null genotype, and risk of bladder cancer: results from the Spanish Bladder Cancer Study and meta-analyses.
BACKGROUND: Many reported associations between common genetic polymorphisms and complex diseases have not been confirmed in subsequent studies. An exception could be the association between NAT2 slow acetylation, GSTM1 null genotype, and bladder-cancer risk. However, current evidence is based on meta-analyses of relatively small studies (range 23-374 cases) with some evidence of publication bias and study heterogeneity. Associations between polymorphisms in other NAT and GST genes and bladder-cancer risk have been inconsistent. METHODS: We investigated polymorphisms in NAT2, GSTM1, NAT1, GSTT1, GSTM3, and GSTP1 in 1150 patients with transitional-cell carcinoma of the urinary bladder and 1149 controls in Spain; all the participants were white. We also carried out meta-analyses of NAT2, GSTM1, and bladder cancer that included more than twice as many cases as in previous reports. FINDINGS: In our study, the odds ratios for bladder cancer for individuals with deletion of one or two copies of the GSTM1 gene were 1.2 (95% CI 0.8-1.7) and 1.9 (1.4-2.7) respectively (p for trend <0.0001). Compared with NAT2 rapid or intermediate acetylators, NAT2 slow acetylators had an increased overall risk of bladder cancer (1.4 [1.2-1.7]) that was stronger for cigarette smokers than for never smokers (p for interaction 0.008). No significant associations were found with the other polymorphisms. Meta-analyses showed that the overall association for NAT2 was robust (p<0.0001), and case-only meta-analyses provided support for an interaction between NAT2 and smoking (p for interaction 0.009). The overall association for GSTM1 was also robust (p<0.0001) and was not modified by smoking status (p=0.86). INTERPRETATION: The GSTM1 null genotype increases the overall risk of bladder cancer, and the NAT2 slow-acetylator genotype increases risk particularly among cigarette smokers. These findings provide compelling evidence for the role of common polymorphisms in the aetiology of cancer. RELEVANCE TO PRACTICE: Although the relative risks are modest, these polymorphisms could account for up to 31% of bladder cancers because of their high prevalence.
Acetylation↗