Although high-risk mutations in identified major susceptibility genes (DNA mismatch repair genes and
) account for some familial aggregation of colorectal cancer, their population prevalence and the ...causes of the remaining familial aggregation are not known.
We studied the families of 5,744 colorectal cancer cases (probands) recruited from population cancer registries in the United States, Canada, and Australia and screened probands for mutations in mismatch repair genes and
We conducted modified segregation analyses using the cancer history of first-degree relatives, conditional on the proband's age at diagnosis. We estimated the prevalence of mutations in the identified genes, the prevalence of HR for unidentified major gene mutations, and the variance of the residual polygenic component.
We estimated that 1 in 279 of the population carry mutations in mismatch repair genes (
= 1 in 1,946,
= 1 in 2,841,
= 1 in 758,
= 1 in 714), 1 in 45 carry mutations in
, and 1 in 504 carry mutations associated with an average 31-fold increased risk of colorectal cancer in unidentified major genes. The estimated polygenic variance was reduced by 30% to 50% after allowing for unidentified major genes and decreased from 3.3 for age <40 years to 0.5 for age ≥70 years (equivalent to sibling relative risks of 5.1 to 1.3, respectively).
Unidentified major genes might explain one third to one half of the missing heritability of colorectal cancer.
Our findings could aid gene discovery and development of better colorectal cancer risk prediction models.
.
Data regarding the association between folate status and risk of prostate cancer are sparse and conflicting. We studied prostate cancer occurrence in the Aspirin/Folate Polyp Prevention Study, a ...placebo-controlled randomized trial of aspirin and folic acid supplementation for the chemoprevention of colorectal adenomas conducted between July 6, 1994, and December 31, 2006. Participants were followed for up to 10.8 (median = 7.0, interquartile range = 6.0–7.8) years and asked periodically to report all illnesses and hospitalizations. Aspirin alone had no statistically significant effect on prostate cancer incidence, but there were marked differences according to folic acid treatment. Among the 643 men who were randomly assigned to placebo or supplementation with folic acid, the estimated probability of being diagnosed with prostate cancer over a 10-year period was 9.7% (95% confidence interval CI = 6.5% to 14.5%) in the folic acid group and 3.3% (95% CI = 1.7% to 6.4%) in the placebo group (age-adjusted hazard ratio = 2.63, 95% CI = 1.23 to 5.65, Wald test P = .01). In contrast, baseline dietary folate intake and plasma folate in nonmultivitamin users were inversely associated with risk of prostate cancer, although these associations did not attain statistical significance in adjusted analyses. These findings highlight the potential complex role of folate in prostate cancer and the possibly different effects of folic acid–containing supplements vs natural sources of folate.
Changes in epigenetic marks such as DNA methylation and histone acetylation are associated with a broad range of disease traits, including cancer, asthma, metabolic disorders, and various ...reproductive conditions. It seems plausible that changes in epigenetic state may be induced by environmental exposures such as malnutrition, tobacco smoke, air pollutants, metals, organic chemicals, other sources of oxidative stress, and the microbiome, particularly if the exposure occurs during key periods of development. Thus, epigenetic changes could represent an important pathway by which environmental factors influence disease risks, both within individuals and across generations. We discuss some of the challenges in studying epigenetic mediation of pathogenesis and describe some unique opportunities for exploring these phenomena.
CONTEXT Laboratory and epidemiological data suggest that folic acid may have an antineoplastic effect in the large intestine. OBJECTIVE To assess the safety and efficacy of folic acid supplementation ...for preventing colorectal adenomas. DESIGN, SETTING, AND PARTICIPANTS A double-blind, placebo-controlled, 2-factor, phase 3, randomized clinical trial conducted at 9 clinical centers between July 6, 1994, and October 1, 2004. Participants included 1021 men and women with a recent history of colorectal adenomas and no previous invasive large intestine carcinoma. INTERVENTION Participants were randomly assigned in a 1:1 ratio to receive 1 mg/d of folic acid (n = 516) or placebo (n = 505), and were separately randomized to receive aspirin (81 or 325 mg/d) or placebo. Follow-up consisted of 2 colonoscopic surveillance cycles (the first interval was at 3 years and the second at 3 or 5 years later). MAIN OUTCOME MEASURES The primary outcome measure was occurrence of at least 1 colorectal adenoma. Secondary outcomes were the occurrence of advanced lesions (≥25% villous features, high-grade dysplasia, size ≥1 cm, or invasive cancer) and adenoma multiplicity (0, 1-2, or ≥3 adenomas). RESULTS
During the first 3 years, 987 participants (96.7%) underwent colonoscopic follow-up, and the incidence of at least 1 colorectal adenoma was 44.1% for folic acid (n = 221) and 42.4% for placebo (n = 206) (unadjusted risk ratio RR, 1.04; 95% confidence interval CI, 0.90-1.20; P = .58). Incidence of at least 1 advanced lesion was 11.4% for folic acid (n = 57) and 8.6% for placebo (n = 42) (unadjusted RR, 1.32; 95% CI, 0.90-1.92; P = .15). A total of 607 participants (59.5%) underwent a second follow-up, and the incidence of at least 1 colorectal adenoma was 41.9% for folic acid (n = 127) and 37.2% for placebo (n = 113) (unadjusted RR, 1.13; 95% CI, 0.93-1.37; P = .23); and incidence of at least 1 advanced lesion was 11.6% for folic acid (n = 35) and 6.9% for placebo (n = 21) (unadjusted RR, 1.67; 95% CI, 1.00-2.80; P = .05). Folic acid was associated with higher risks of having 3 or more adenomas and of noncolorectal cancers. There was no significant effect modification by sex, age, smoking, alcohol use, body mass index, baseline plasma folate, or aspirin allocation.
CONCLUSIONS Folic acid at 1 mg/d does not reduce colorectal adenoma risk. Further research is needed to investigate the possibility that folic acid supplementation might increase the risk of colorectal neoplasia. TRIAL REGISTRATION
clinicaltrials.gov Identifier: NCT00272324
Background Cigarette smoking is an established risk factor for colorectal cancer. Because colorectal carcinogenesis is a heterogeneous process, we investigated whether cigarette smoking is ...differentially associated with molecularly defined subtypes of colorectal cancer. Methods We evaluated associations between smoking and incident colorectal cancer, overall and by microsatellite instability (MSI) phenotype (MSI-high vs MSI-low or microsatellite stable), CpG island methylator phenotype (CIMP positive or CIMP negative), and BRAF mutation status (BRAF mutation positive or BRAF mutation negative), among 37 399 participants in a population-based cohort study (the Iowa Women’s Health Study). Cigarette smoking (and other exposures) was assessed by self-report at baseline in 1986, including smoking status (never and ever former or current), age at initiation, total duration, average number of cigarettes smoked per day, cumulative pack-years, and induction period. Vital status and state of residence were determined by mailed follow-up questionnaires in 1987, 1989, 1992, and 1997 and by linkage to Iowa death certificate records. Nonrespondents were checked via the National Death Index to identify descendants. Participants with newly diagnosed (ie, incident) colorectal cancer were identified through annual linkage with the Iowa Cancer Registry. Archived paraffin-embedded tumor tissue specimens were obtained for 555 patients with colorectal cancer who were diagnosed from January 1, 1986, through December 31, 2002, and MSI status, CIMP status, and BRAF status were determined. Multivariable Cox regression models were fit to estimate relative risks (RRs) and 95% confidence intervals (CIs). Results Ever-smokers were at moderately increased risk for incident colorectal cancer (RR = 1.19, 95% CI = 1.05 to 1.35) compared with never-smokers. Higher risk estimates were observed for current smokers with MSI-high tumors (RR = 1.99, 95% CI = 1.26 to 3.14), CIMP-positive tumors (RR = 1.88, 95% CI = 1.22 to 2.90), and BRAF mutation–positive tumors (RR = 1.92, 95% CI = 1.22 to 3.02). Other smoking-related variables (ie, age at initiation, total duration, average number of cigarettes smoked per day, cumulative pack-years, and induction period) were also associated with MSI-high, CIMP-positive, and BRAF mutation–positive tumor subtypes. Conversely, cigarette smoking status (ever vs never) was not associated with the MSI-low or microsatellite stable (RR = 1.00, 95% CI = 0.79 to 1.25), CIMP-negative (RR = 1.02, 95% CI = 0.81 to 1.30), or BRAF mutation–negative subtypes (RR = 1.00, 95% CI = 0.65 to 1.27). Conclusions In this prospective study of older women, cigarette smoking was associated with the MSI-high, CIMP-positive, and BRAF mutation–positive colorectal cancer subtypes, which indicates that epigenetic modification may be functionally involved in smoking-related colorectal carcinogenesis.
“Cancer Center Catchment Area Assessment”—Letter Escobedo, Loraine A.; Surani, Zul; Haile, Robert W.
Cancer epidemiology, biomarkers & prevention,
07/2022, Letnik:
31, Številka:
7
Journal Article
Background
Initiating screening at an earlier age based on cancer family history is one of the primary recommended strategies for the prevention and detection of early‐onset colorectal cancer ...(EOCRC), but data supporting the effectiveness of this approach are limited. The authors assessed the performance of family history–based guidelines for identifying individuals with EOCRC.
Methods
The authors conducted a population‐based, case‐control study of individuals aged 40 to 49 years with (2473 individuals) and without (772 individuals) incident CRC in the Colon Cancer Family Registry from 1998 through 2007. They estimated the sensitivity and specificity of family history–based criteria jointly recommended by the American Cancer Society, the US Multi‐Society Task Force on CRC, and the American College of Radiology in 2008 for early screening, and the age at which each participant could have been recommended screening initiation if these criteria had been applied.
Results
Family history–based early screening criteria were met by approximately 25% of cases (614 of 2473 cases) and 10% of controls (74 of 772 controls), with a sensitivity of 25% and a specificity of 90% for identifying EOCRC cases aged 40 to 49 years. Among 614 individuals meeting early screening criteria, 98.4% could have been recommended screening initiation at an age younger than the observed age of diagnosis.
Conclusions
Of CRC cases aged 40 to 49 years, 1 in 4 met family history–based early screening criteria, and nearly all cases who met these criteria could have had CRC diagnosed earlier (or possibly even prevented) if earlier screening had been implemented as per family history–based guidelines. Additional strategies are needed to improve the detection and prevention of EOCRC for individuals not meeting family history criteria for early screening.
Data supporting initiating screening at an earlier age based on family history as a strategy for the detection and prevention of early‐onset colorectal cancer (CRC) are limited. In a population‐based, case‐control study of individuals aged 40 to 49 years, the authors report that 1 in 4 meet guideline criteria for earlier screening, and that nearly all of those who meet these criteria could have had CRC diagnosed earlier (or possibly even prevented) if earlier screening had been implemented as per guidelines.
Differences in incidence, prognosis, and treatment response suggest gene expression patterns may discern breast cancer subtypes with unique risk factor profiles; however, previous results were based ...predominantly on older women. In this study, we examined similar relationships in women ≤56 years, classified by immunohistochemical staining for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 for 890 breast cancer cases and 3,432 frequency-matched population-based controls. Odds ratios (OR) and 95% confidence intervals (CI) for tumor subtypes were calculated using multivariate polytomous regression models. A total of 455 (51.1%) tumors were considered luminal A, 72 (8.1%) luminal B, 117 (13.1%) non-luminal HER-2/neu+, and 246 (27.6%) triple negative. Triple negative tumors were associated with breast feeding duration (per 6 months: OR = 0.76, 95% CI 0.64–0.90). Among premenopausal women, increasing body size was more strongly associated with luminal B (OR = 1.73, 95% CI 1.07–2.77) and triple negative tumors (OR = 1.67, 95% CI 1.22–2.28). A history of benign breast disease was associated only with increased risk of luminal A tumors (OR = 1.89, 95% CI 1.43–2.50). A family history of breast cancer was a risk factor for luminal A tumors (OR = 1.93, 95% CI 1.38–2.70) regardless of age, and triple negative tumors with higher risks for women <45 (OR = 5.02, 95% CI 2.82–8.92;
P
for age interaction = 0.005). We found that little-to-no breastfeeding and high BMI were associated with increased risk of triple negative breast cancer. That some risk factors differ by molecular subtypes suggests etiologic heterogeneity in breast carcinogenesis among young women.
Some serrated polyps of the colorectum are likely preinvasive lesions, evolving through a newly recognized serrated pathway
to colorectal cancer. To assess possible risk and protective factors for ...serrated polyps and particularly to explore differences
in risk factors between polyps in the right and left colorectum, we pooled data from three large multicenter chemoprevention
trials. A serrated polyp was defined broadly as any serrated lesion (hyperplastic, sessile serrated adenoma, “traditional”
serrated adenoma, mixed adenoma) diagnosed during each trial's main treatment period of ∼3 to 4 years. Using generalized linear
regression, we computed risk ratios and 95% confidence intervals as measures of the association between risk for serrated
polyps and demographic, lifestyle, and dietary variables. Of the 2,830 subjects that completed at least one follow-up exam
after randomization, 675 (23.9%) had at least one left-sided serrated polyp and 261 (9.2%) had at least one right-sided lesion.
In the left colorectum, obesity, cigarette smoking, dietary fat, total energy intake, and red meat intake were associated
with an increased risk for serrated polyps. In the right colon, aspirin treatment was associated with a reduced risk and family
history of polyps and folate treatment were associated with an increased risk for serrated polyps. Our results suggest that
several common lifestyle and dietary variables are associated with risk for serrated polyps, and some of these may differ
for the right and left colorectum. (Cancer Epidemiol Biomarkers Prev 2009;18(8):2310–7)
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