Germline mutations in PMS2 and MLH1 in individuals with solitary loss of PMS2 expression in colorectal carcinomas from the Colon Cancer Family Registry Cohort

OBJECTIVES

Immunohistochemistry for DNA mismatch repair proteins is used to screen for Lynch syndrome in individuals with colorectal carcinoma (CRC). Although solitary loss of PMS2 expression is indicative of carrying a germline mutation in PMS2, previous studies reported MLH1 mutation in some cases. We determined the prevalence of MLH1 germline mutations in a large cohort of individuals with a CRC demonstrating solitary loss of PMS2 expression.

DESIGN

This cohort study included 88 individuals affected with a PMS2-deficient CRC from the Colon Cancer Family Registry Cohort. Germline PMS2 mutation analysis (long-range PCR and multiplex ligation-dependent probe amplification) was followed by MLH1 mutation testing (Sanger sequencing and multiplex ligation-dependent probe amplification).

RESULTS

Of the 66 individuals with complete mutation screening, we identified a pathogenic PMS2 mutation in 49 (74%), a pathogenic MLH1 mutation in 8 (12%) and a MLH1 variant of uncertain clinical significance predicted to be damaging by in silico analysis in 3 (4%); 6 (9%) carried variants likely to have no clinical significance. Missense point mutations accounted for most alterations (83%; 9/11) in MLH1. The MLH1 c.113A> G p.Asn38Ser mutation was found in 2 related individuals. One individual who carried the MLH1 intronic mutation c.677+3A>G p.Gln197Argfs*8 leading to the skipping of exon 8, developed 2 tumours, both of which retained MLH1 expression.

CONCLUSIONS

A substantial proportion of CRCs with solitary loss of PMS2 expression are associated with a deleterious MLH1 germline mutation supporting the screening for MLH1 in individuals with tumours of this immunophenotype, when no PMS2 mutation has been identified.

Cigarette Smoking Before and After Breast Cancer Diagnosis: Mortality From Breast Cancer and Smoking-Related Diseases

PURPOSE

Cigarette smoking increases overall mortality, but it is not established whether smoking is associated with breast cancer prognosis.

METHODS

We evaluated the association between smoking status before and after breast cancer diagnosis and mortality in the Collaborative Breast Cancer and Women's Longevity Study, a population-based prospective observational study conducted in Wisconsin, New Hampshire, and Massachusetts. Participants included 20,691 women, ages 20 to 79 years, diagnosed with incident localized or regional invasive breast cancer between 1988 and 2008; a subset of 4,562 of these women were recontacted a median of 6 years after diagnosis. Hazard ratios (HRs) with 95% CIs were calculated according to smoking status for death as a result of breast cancer; cancers of the lung, pharynx, or intrathoracic organs; other cancer; respiratory disease; and cardiovascular disease.

RESULTS

During a median of 12 years, 6,778 women died, including 2,894 who died as a result of breast cancer. Active smokers 1 year before breast cancer diagnosis were more likely than never smokers to die of breast cancer (HR, 1.25; 95% CI, 1.13 to 1.37), respiratory cancer (HR, 14.48; 95% CI, 9.89 to 21.21), other respiratory disease (HR, 6.02; 95% CI, 4.55 to 7.97), and cardiovascular disease (HR, 2.08; 95% CI, 1.80 to 2.41). The 10% of women who continued to smoke after diagnosis were more likely than never smokers to die of breast cancer (HR, 1.72; 95% CI, 1.13 to 2.60). When compared with women who continued to smoke after diagnosis, those who quit smoking after diagnosis had lower mortality from breast cancer (HR, 0.67; 95% CI, 0.38 to 1.19) and respiratory cancer (HR, 0.39; 95% CI, 0.16 to 0.95).

CONCLUSION

Smoking before or after diagnosis was associated with a higher mortality from breast cancer and several other causes.

Fractures in association with breast and endometrial cancer survival in the Women’s Health Initiative

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Background: Postmenopausal fracture rates appear to be an integrated marker of usual estrogen levels and have been associated with decreased risk of breast and endometrial cancer. The association between fractures and cancer mortality has been difficult to assess, as fractures are a consequence of both the pathological process and the treatment of cancer. Due to the reduced proliferative effects of the hormonal milieu, pre-diagnosis fractures may be a hallmark of decreased cancer mortality. Methods: We evaluated a cohort of breast (N = 6,458) and endometrial (N = 1,138) cancer cases who were diagnosed with cancer during the Women’s Health Initiative (WHI; 1992-2010). Fracture history was assessed by combining baseline reports of fractures prior to WHI and after age 50; with fractures ascertained during WHI follow-up, but prior to cancer diagnosis. We used Cox proportional hazards models based on time since cancer diagnosis to estimate hazard ratios (HR) with 95% confidence intervals for overall and cancer-specific mortality, comparing women with prior fractures to those without fractures. Clinical factors, including bisphosphonate and hormone use, were in the model. Results: Among breast cancer cases, during the average 6.2 years of follow-up, 1,464 had a prior fracture and 905 deaths occurred (415 due to breast cancer). Among endometrial cancer cases, during follow-up, 267 had a prior fracture and 192 deaths occurred (83 due to endometrial cancer). Any pre-diagnosis fracture was associated with increased all-cause mortality (breast HR: 1.39 (1.20, 1.62); endometrial HR: 1.41 (1.02, 1.95)). Among breast cancer cases, the strongest association was with hip fracture (HR: 2.76 (1.80, 4.25)). Associations with cancer-specific mortality were similar in direction and magnitude, but did not reach statistical significance. Conclusions: A history of pre-diagnostic fractures was associated with increased overall but not cancer-specific mortality. Fracture history may be indicative of frailty or other co-morbidities. Breast and endometrial cancer cases with a fracture history may benefit from concurrent supportive care to mediate risk of death due to co-morbid health conditions.

CYP24A1 variant modifies the association between use of oestrogen plus progestogen therapy and colorectal cancer risk

BACKGROUND

Menopausal hormone therapy (MHT) use has been consistently associated with a decreased risk of colorectal cancer (CRC) in women. Our aim was to use a genome-wide gene-environment interaction analysis to identify genetic modifiers of CRC risk associated with use of MHT.

METHODS

We included 10 835 postmenopausal women (5419 cases and 5416 controls) from 10 studies. We evaluated use of any MHT, oestrogen-only (E-only) and combined oestrogen-progestogen (E+P) hormone preparations. To test for multiplicative interactions, we applied the empirical Bayes (EB) test as well as the Wald test in conventional case-control logistic regression as primary tests. The Cocktail test was used as secondary test.

RESULTS

The EB test identified a significant interaction between rs964293 at 20q13.2/CYP24A1 and E+P (interaction OR (95% CIs)=0.61 (0.52-0.72), P=4.8 × 10(-9)). The secondary analysis also identified this interaction (Cocktail test OR=0.64 (0.52-0.78), P=1.2 × 10(-5) (alpha threshold=3.1 × 10(-4)). The ORs for association between E+P and CRC risk by rs964293 genotype were as follows: C/C, 0.96 (0.61-1.50); A/C, 0.61 (0.39-0.95) and A/A, 0.40 (0.22-0.73), respectively.

CONCLUSIONS

Our results indicate that rs964293 modifies the association between E+P and CRC risk. The variant is located near CYP24A1, which encodes an enzyme involved in vitamin D metabolism. This novel finding offers additional insight into downstream pathways of CRC etiopathogenesis.

Genetic variation in metallothionein and metal-regulatory transcription factor 1 in relation to urinary cadmium, copper, and zinc

BACKGROUND

Metallothionein (MT) proteins play critical roles in the physiological handling of both essential (Cu and Zn) and toxic (Cd) metals. MT expression is regulated by metal-regulatory transcription factor 1 (MTF1). Hence, genetic variation in the MT gene family and MTF1 might influence excretion of these metals.

METHODS

321 women were recruited in Seattle, WA and Las Cruces, NM and provided demographic information, urine samples for measurement of metal concentrations by mass spectrometry and creatinine, and blood or saliva for extraction of DNA. Forty-one single nucleotide polymorphisms (SNPs) within the MTF1 gene region and the region of chromosome 16 encoding the MT gene family were selected for genotyping in addition to an ancestry informative marker panel. Linear regression was used to estimate the association of SNPs with urinary Cd, Cu, and Zn, adjusted for age, urinary creatinine, smoking history, study site, and ancestry.

RESULTS

Minor alleles of rs28366003 and rs10636 near the MT2A gene were associated with lower urinary Cd, Cu, and Zn. Minor alleles of rs8044719 and rs1599823, near MT1A and MT1B, were associated with lower urinary Cd and Zn, respectively. Minor alleles of rs4653329 in MTF1 were associated with lower urinary Cd.

CONCLUSIONS

These results suggest that genetic variation in the MT gene region and MTF1 influences urinary Cd, Cu, and Zn excretion.

Meta-analysis of genome-wide association studies identifies common susceptibility polymorphisms for colorectal and endometrial cancer near SH2B3 and TSHZ1

High-risk mutations in several genes predispose to both colorectal cancer (CRC) and endometrial cancer (EC). We therefore hypothesised that some lower-risk genetic variants might also predispose to both CRC and EC. Using CRC and EC genome-wide association series, totalling 13,265 cancer cases and 40,245 controls, we found that the protective allele [G] at one previously-identified CRC polymorphism, rs2736100 near TERT, was associated with EC risk (odds ratio (OR) = 1.08, P = 0.000167); this polymorphism influences the risk of several other cancers. A further CRC polymorphism near TERC also showed evidence of association with EC (OR = 0.92; P = 0.03). Overall, however, there was no good evidence that the set of CRC polymorphisms was associated with EC risk, and neither of two previously-reported EC polymorphisms was associated with CRC risk. A combined analysis revealed one genome-wide significant polymorphism, rs3184504, on chromosome 12q24 (OR = 1.10, P = 7.23 × 10(-9)) with shared effects on CRC and EC risk. This polymorphism, a missense variant in the gene SH2B3, is also associated with haematological and autoimmune disorders, suggesting that it influences cancer risk through the immune response. Another polymorphism, rs12970291 near gene TSHZ1, was associated with both CRC and EC (OR = 1.26, P = 4.82 × 10(-8)), with the alleles showing opposite effects on the risks of the two cancers.

Common genetic variation and survival after colorectal cancer diagnosis: a genome-wide analysis

Genome-wide association studies have identified several germline single nucleotide polymorphisms (SNPs) significantly associated with colorectal cancer (CRC) incidence. Common germline genetic variation may also be related to CRC survival. We used a discovery-based approach to identify SNPs related to survival outcomes after CRC diagnosis. Genome-wide genotyping arrays were conducted for 3494 individuals with invasive CRC enrolled in six prospective cohort studies (median study-specific follow-up = 4.2-8.1 years). In pooled analyses, we used Cox regression to assess SNP-specific associations with CRC-specific and overall survival, with additional analyses stratified by stage at diagnosis. Top findings were followed-up in independent studies. A P value threshold of P < 5×10(-8) in analyses combining discovery and follow-up studies was required for genome-wide significance. Among individuals with distant-metastatic CRC, several SNPs at 6p12.1, nearest the ELOVL5 gene, were statistically significantly associated with poorer survival, with the strongest associations noted for rs209489 [hazard ratio (HR) = 1.8, P = 7.6×10(-10) and HR = 1.8, P = 3.7×10(-9) for CRC-specific and overall survival, respectively). No SNPs were statistically significantly associated with survival among all cases combined or in cases without distant-metastases. SNPs in 6p12.1/ELOVL5 were associated with survival outcomes in individuals with distant-metastatic CRC, and merit further follow-up for functional significance. Findings from this genome-wide association study highlight the potential importance of genetic variation in CRC prognosis and provide clues to genomic regions of potential interest.

Partnership Status and Socioeconomic Factors in Relation to Health Behavior Changes after a Diagnosis of Ductal Carcinoma In Situ

BACKGROUND

Change in health behaviors can occur among women newly diagnosed with ductal carcinoma in situ (DCIS). We sought to understand whether partnership status and socioeconomic status (SES) affected behavioral changes in body weight, physical activity, alcohol consumption, and smoking.

METHODS

The Wisconsin In Situ Cohort (WISC) study comprises 1,382 women diagnosed with DCIS with information on demographics, SES factors, and pre- and post-DCIS diagnosis health-related behaviors. Logistic regression models were used to determine the association between partnership status, education, and income with change in behavior variables.

RESULTS

Higher educational attainment was associated with lower likelihood of stopping physical activity [OR, 0.45; 95% confidence interval (CI), 0.32-0.63; college vs. high school degree], or starting to drink alcohol (OR, 0.34; 95% CI, 0.15-0.80). Results suggested that higher family income was associated with lower likelihood of gaining >5% body mass index (P = 0.07) or stopping physical activity (P = 0.09). Living with a partner was not strongly associated with behavior changes.

CONCLUSION

Higher educational attainment and higher income, but not living with a partner, were associated with positive health behaviors after a DCIS diagnosis.

IMPACT

The associations between higher educational attainment and, to a lesser extent, higher income with positive health behaviors underscore the importance of considering SES when identifying those at risk for negative behavioral change after DCIS diagnosis.

Mutation spectrum and risk of colorectal cancer in African American families with Lynch syndrome

BACKGROUND & AIMS

African Americans (AAs) have the highest incidence of and mortality resulting from colorectal cancer (CRC) in the United States. Few data are available on genetic and nongenetic risk factors for CRC among AAs. Little is known about cancer risks and mutations in mismatch repair (MMR) genes in AAs with the most common inherited CRC condition, Lynch syndrome. We aimed to characterize phenotype, mutation spectrum, and risk of CRC in AAs with Lynch syndrome.

METHODS

We performed a retrospective study of AAs with mutations in MMR genes (MLH1, MSH2, MSH6, and PMS2) using databases from 13 US referral centers. We analyzed data on personal and family histories of cancer. Modified segregation analysis conditioned on ascertainment criteria was used to estimate age- and sex-specific CRC cumulative risk, studying members of the mutation-carrying families.

RESULTS

We identified 51 AA families with deleterious mutations that disrupt function of the MMR gene product: 31 in MLH1 (61%), 11 in MSH2 (21%), 3 in MSH6 (6%), and 6 in PMS2 (12%); 8 mutations were detected in more than 1 individual, and 11 have not been previously reported. In the 920 members of the 51 families with deleterious mutations, the cumulative risks of CRC at 80 years of age were estimated to be 36.2% (95% confidence interval [CI], 10.5%-83.9%) for men and 29.7% (95% CI, 8.31%-76.1%) for women. CRC risk was significantly higher among individuals with mutations in MLH1 or MSH2 (hazard ratio, 13.9; 95% CI, 3.44-56.5).

CONCLUSIONS

We estimate the cumulative risk for CRC in AAs with MMR gene mutations to be similar to that of individuals of European descent with Lynch syndrome. Two-thirds of mutations were found in MLH1, some of which were found in multiple individuals and some that have not been previously reported. Differences in mutation spectrum are likely to reflect the genetic diversity of this population.

Clinicopathologic Risk Factor Distributions for MLH1 Promoter Region Methylation in CIMP-Positive Tumors

BACKGROUND

The CpG island methylator phenotype (CIMP) is a major molecular pathway in colorectal cancer. Approximately 25% to 60% of CIMP tumors are microsatellite unstable (MSI-H) due to DNA hypermethylation of the MLH1 gene promoter. Our aim was to determine if the distributions of clinicopathologic factors in CIMP-positive tumors with MLH1 DNA methylation differed from those in CIMP-positive tumors without DNA methylation of MLH1.

METHODS

We assessed the associations between age, sex, tumor-site, MSI status BRAF and KRAS mutations, and family colorectal cancer history with MLH1 methylation status in a large population-based sample of CIMP-positive colorectal cancers defined by a 5-marker panel using unconditional logistic regression to assess the odds of MLH1 methylation by study variables.

RESULTS

Subjects with CIMP-positive tumors without MLH1 methylation were significantly younger, more likely to be male, and more likely to have distal colon or rectal primaries and the MSI-L phenotype. CIMP-positive MLH1-unmethylated tumors were significantly less likely than CIMP-positive MLH1-methylated tumors to harbor a BRAF V600E mutation and significantly more likely to harbor a KRAS mutation. MLH1 methylation was associated with significantly better overall survival (HR, 0.50; 95% confidence interval, 0.31-0.82).

CONCLUSIONS

These data suggest that MLH1 methylation in CIMP-positive tumors is not a completely random event and implies that there are environmental or genetic determinants that modify the probability that MLH1 will become methylated during CIMP pathogenesis.

IMPACT

MLH1 DNA methylation status should be taken into account in etiologic studies.

Abstract A52: Oral contraceptive use and risk of colorectal polyps in a colonoscopy based study in western Washington state

Background: Most colorectal cancers arise from polyp precursor lesions, including advanced adenomas and a subset of serrated polyps, termed sessile serrated polyps. Growing literature on oral contraceptives (OC) use and risk of colorectal cancer suggests an inverse association. However, very little is known about the role of OC in the development of colorectal polyps. We investigated the relationship between OC use and the risk of subsets of colorectal polyps in a colonoscopy based study in western Washington State.

Methods: Study participants were 20-79 year-old women enrollees at Group Health, an integrated health care system in Seattle, Washington who underwent a colonscopy for any indication from 1998-2007. Study eligible participants completed a structured interview to collect risk factor information, including reproductive history and exogenous hormone use. OC use was categorized according to ever use, recency of use, and duration of use. Participants were diagnosed as having adenomas (n=298), serrated polyps (n=336), both types of polyps (n= 105) or as polyp-free controls (n=615) on the basis of a standardized pathology review. Multivariable polytomous logistic regression was used to compare case groups with polyp-free controls and other case groups; odds ratios (OR) and 95% confidence intervals were estimated adjusted for age, race, educational status, body mass index, smoking, alcohol intake, anti-inflammatory drug use, use of postmenopausal hormones, parity and age at first birth.

Results: Ever use of OC was not associated with risk for adenomas (adjusted OR 0.82, 95% CI 0.57-1.20) or serrated polyps (adjusted OR 0.93, 95% CI 0.64-1.36) while the risk for synchronous presence of both types of polyps was elevated (adjusted OR 1.43, 95% CI 0.77-2.67) (p=0.39 for the three polyp subtypes). Strength of association did not vary significantly between adenomas and serrated polyps for duration of use (p=0.43) and time since last use (p=0.75). Additionally, the associations did not differ significantly by age, lesion severity (advanced vs. nonadvanced for adenomas, sessile serrated vs. hyperplastic for serrated polyps), or location (right vs left) for either adenomas or serrated polyps.

Conclusions: We observed no strong evidence that adenomas or serrated polyps were associated with ever use of OC pills. Although the majority of studies suggest a reversible effect of exogenous postmenopausal hormones on colorectal neoplasia, we did not find any association between time since last use of OC pills and development of either types of polyps. Further larger studies are needed to better understand the mechanistic processes through which oral contraceptives may be associated with the development of adenomas and serrated polyps.

Citation Format: Sheetal Hardikar, Andrea N. Burnett-Hartman, Polly A. Newcomb. Oral contraceptive use and risk of colorectal polyps in a colonoscopy based study in western Washington state. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A52.

Genetic determinants of telomere length and risk of common cancers: a Mendelian randomization study

Epidemiological studies have reported inconsistent associations between telomere length (TL) and risk for various cancers. These inconsistencies are likely attributable, in part, to biases that arise due to post-diagnostic and post-treatment TL measurement. To avoid such biases, we used a Mendelian randomization approach and estimated associations between nine TL-associated SNPs and risk for five common cancer types (breast, lung, colorectal, ovarian and prostate cancer, including subtypes) using data on 51 725 cases and 62 035 controls. We then used an inverse-variance weighted average of the SNP-specific associations to estimate the association between a genetic score representing long TL and cancer risk. The long TL genetic score was significantly associated with increased risk of lung adenocarcinoma (P = 6.3 × 10(-15)), even after exclusion of a SNP residing in a known lung cancer susceptibility region (TERT-CLPTM1L) P = 6.6 × 10(-6)). Under Mendelian randomization assumptions, the association estimate [odds ratio (OR) = 2.78] is interpreted as the OR for lung adenocarcinoma corresponding to a 1000 bp increase in TL. The weighted TL SNP score was not associated with other cancer types or subtypes. Our finding that genetic determinants of long TL increase lung adenocarcinoma risk avoids issues with reverse causality and residual confounding that arise in observational studies of TL and disease risk. Under Mendelian randomization assumptions, our finding suggests that longer TL increases lung adenocarcinoma risk. However, caution regarding this causal interpretation is warranted in light of the potential issue of pleiotropy, and a more general interpretation is that SNPs influencing telomere biology are also implicated in lung adenocarcinoma risk.

Association between body mass index and mortality for colorectal cancer survivors: overall and by tumor molecular phenotype

BACKGROUND

Microsatellite instability (MSI) and BRAF mutation status are associated with colorectal cancer survival, whereas the role of body mass index (BMI) is less clear. We evaluated the association between BMI and colorectal cancer survival, overall and by strata of MSI, BRAF mutation, sex, and other factors.

METHODS

This study included 5,615 men and women diagnosed with invasive colorectal cancer who were followed for mortality (maximum: 14.7 years; mean: 5.9 years). Prediagnosis BMI was derived from self-reported weight approximately one year before diagnosis and height. Tumor MSI and BRAF mutation status were available for 4,131 and 4,414 persons, respectively. Multivariable hazard ratios (HR) and 95% confidence intervals (CI) were estimated from delayed-entry Cox proportional hazards models.

RESULTS

In multivariable models, high prediagnosis BMI was associated with higher risk of all-cause mortality in both sexes (per 5-kg/m(2); HR, 1.10; 95% CI, 1.06-1.15), with similar associations stratified by sex (Pinteraction: 0.41), colon versus rectum (Pinteraction: 0.86), MSI status (Pinteraction: 0.84), and BRAF mutation status (Pinteraction: 0.28). In joint models, with MS-stable/MSI-low and normal BMI as the reference group, risk of death was higher for MS-stable/MSI-low and obese BMI (HR, 1.32; P value: 0.0002), not statistically significantly lower for MSI-high and normal BMI (HR, 0.86; P value: 0.29), and approximately the same for MSI-high and obese BMI (HR, 1.00; P value: 0.98).

CONCLUSIONS

High prediagnosis BMI was associated with increased mortality; this association was consistent across participant subgroups, including strata of tumor molecular phenotype.

IMPACT

High BMI may attenuate the survival benefit otherwise observed with MSI-high tumors.

Analyses of 7,635 Patients with Colorectal Cancer Using Independent Training and Validation Cohorts Show That rs9929218 in CDH1 Is a Prognostic Marker of Survival

PURPOSE

Genome-wide association studies have identified numerous loci associated with colorectal cancer risk. Several of these have also been associated with patient survival, although none have been validated. Here, we used large independent training and validation cohorts to identify robust prognostic biomarkers for colorectal cancer.

EXPERIMENTAL DESIGN

In our training phase, we analyzed 20 colorectal cancer-risk SNPs from 14 genome-wide associated loci, for their effects on survival in 2,083 patients with advanced colorectal cancer. A Cox survival model was used, stratified for treatment, adjusted for known prognostic factors, and corrected for multiple testing. Three SNPs were subsequently analyzed in an independent validation cohort of 5,552 colorectal cancer patients. A validated SNP was analyzed by disease stage and response to treatment.

RESULTS

Three variants associated with survival in the training phase; however, only rs9929218 at 16q22 (intron 2 of CDH1, encoding E-cadherin) was significant in the validation phase. Patients homozygous for the minor allele (AA genotype) had worse survival (training phase HR, 1.43; 95% confidence intervals; CI, 1.20-1.71, P = 5.8 × 10(-5); validation phase HR, 1.18; 95% CI, 1.01-1.37, P = 3.2 × 10(-2); combined HR, 1.28; 95% CI, 1.14-1.43, P = 2.2 × 10(-5)). This effect was independent of known prognostic factors, and was significant amongst patients with stage IV disease (P = 2.7 × 10(-5)). rs9929218 was also associated with poor response to chemotherapy (P = 3.9 × 10(-4)).

CONCLUSIONS

We demonstrate the potential of common inherited genetic variants to inform patient outcome and show that rs9929218 identifies approximately 8% of colorectal cancer patients with poor prognosis. rs9929218 may affect CDH1 expression and E-cadherin plays a role in epithelial-to-mesenchymal transition providing a mechanism underlying its prognostic potential. Clin Cancer Res; 21(15); 3453-61. ©2015 AACR.

Lynch syndrome and cervical cancer

Carriers of germline mutations in DNA mismatch repair (MMR) genes are at increased risk of several cancers including colorectal and gynecologic cancers (Lynch syndrome). There is no substantial evidence that these mutations are associated with an increased risk of cervical cancer. A total of 369 families with at least one carrier of a mutation in a MMR gene (133 MLH1, 174 MSH2, 35 MSH6 and 27 PMS2) were ascertained via population cancer registries or via family cancer clinics in Australia, New Zealand, Canada, and USA. Personal and family histories of cancer were obtained from participant interviews. Modified segregation analysis was used to estimate the hazard ratio (incidence rates for carriers relative to those for the general population), and age-specific cumulative risks of cervical cancer for carriers. A total of 65 cases of cervical cancer were reported (including 10 verified by pathology reports). The estimated incidence was 5.6 fold (95% CI: 2.3-13.8; p = 0.001) higher for carriers than for the general population with a corresponding cumulative risk to 80 years of 4.5% (95% CI: 1.9-10.7%) compared with 0.8% for the general population. The mean age at diagnosis was 43.1 years (95% CI: 40.0-46.2), 3.9 years younger than the reported USA population mean of 47.0 years (p = 0.02). Women with MMR gene mutations were found to have an increased risk of cervical cancer. Due to limited pathology verification we cannot be certain that a proportion of these cases were not lower uterine segment endometrial cancers involving the endocervix, a recognized cancer of Lynch syndrome.

Female Hormonal Factors and the Risk of Endometrial Cancer in Lynch Syndrome

IMPORTANCE

Apart from hysterectomy, there is no consensus recommendation for reducing endometrial cancer risk for women with a mismatch repair gene mutation (Lynch syndrome).

OBJECTIVE

To investigate the association between hormonal factors and endometrial cancer risk in Lynch syndrome.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study included 1128 women with a mismatch repair gene mutation identified from the Colon Cancer Family Registry. Data were analyzed with a weighted cohort approach. Participants were recruited between 1997 and 2012 from centers across the United States, Australia, Canada, and New Zealand.

EXPOSURES

Age at menarche, first and last live birth, and menopause; number of live births; hormonal contraceptive use; and postmenopausal hormone use.

MAIN OUTCOMES AND MEASURES

Self-reported diagnosis of endometrial cancer.

RESULTS

Endometrial cancer was diagnosed in 133 women (incidence rate per 100 person-years, 0.29; 95% CI, 0.24 to 0.34). Endometrial cancer was diagnosed in 11% (n = 70) of women with age at menarche greater than or equal to 13 years compared with 12.6% (n = 57) of women with age at menarche less than 13 years (incidence rate per 100 person-years, 0.27 vs 0.31; rate difference, -0.04 [95% CI, -0.15 to 0.05]; hazard ratio per year, 0.85 [95% CI, 0.73 to 0.99]; P = .04). Endometrial cancer was diagnosed in 10.8% (n = 88) of parous women compared with 14.4% (n = 40) of nulliparous women (incidence rate per 100 person-years, 0.25 vs 0.43; rate difference, -0.18 [95% CI, -0.32 to -0.04]; hazard ratio, 0.21 [95% CI, 0.10 to 0.42]; P < .001). Endometrial cancer was diagnosed in 8.7% (n = 70) of women who used hormonal contraceptives greater than or equal to 1 year compared with 19.2% (n = 57) of women who used contraceptives less than 1 year (incidence rate per 100 person-years, 0.22 vs 0.45; rate difference, -0.23 [95% CI, -0.36 to -0.11]; hazard ratio, 0.39 [95% CI, 0.23 to 0.64]; P < .001). There was no statistically significant association between endometrial cancer and age at first and last live birth, age at menopause, and postmenopausal hormone use.

CONCLUSIONS AND RELEVANCE

For women with a mismatch repair gene mutation, some endogenous and exogenous hormonal factors were associated with a lower risk of endometrial cancer. These directions and strengths of associations were similar to those for the general population. If replicated, these findings suggest that women with a mismatch repair gene mutation may be counseled like the general population in regard to hormonal influences on endometrial cancer risk.

Aspirin, Ibuprofen, and the Risk of Colorectal Cancer in Lynch Syndrome

BACKGROUND

Inheritance of a germline mutation in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2 causes a high risk of colorectal and other cancers (Lynch Syndrome). Use of aspirin has been shown to be associated with a reduced risk of colorectal cancer for the general population as well as for MMR gene mutation carriers. The aim of this study was to determine whether use of aspirin and ibuprofen in a nontrial setting is associated with the risk of colorectal cancer risk for MMR gene mutation carriers.

METHODS

We included 1858 participants in the Colon Cancer Family Registry who had been found to have a pathogenic germline mutation in a MMR gene (carriers). We used weighted Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

A total of 714 carriers (38%) were diagnosed with colorectal cancer at a mean age of 42.4 (standard deviation 10.6) years. A reduced risk of colorectal cancer was associated with aspirin use (for 1 month to 4.9 years: HR = 0.49, 95% CI = 0.27 to 0.90, P = .02; for ≥5 years: HR = 0.25, 95% CI = 0.10 to 0.62, P = .003) and ibuprofen use (for 1 month to 4.9 years: HR = 0.38, 95% CI = 0.18 to 0.79, P = .009; for ≥5 years: HR = 0.26, 95% CI = 0.10 to 0.69, P = .007), compared with less than one month of use.

CONCLUSION

Our results provide additional evidence that, for MMR gene mutation carriers, use of aspirin and ibuprofen might be effective in reducing their high risk of colorectal cancer.

Variation in Breast Cancer-Risk Factor Associations by Method of Detection: Results From a Series of Case-Control Studies

Concerns about breast cancer overdiagnosis have increased the need to understand how cancers detected through screening mammography differ from those first detected by a woman or her clinician. We investigated risk factor associations for invasive breast cancer by method of detection within a series of case-control studies (1992-2007) carried out in Wisconsin, Massachusetts, and New Hampshire (n=15,648 invasive breast cancer patients and 17,602 controls aged 40-79 years). Approximately half of case women reported that their cancer had been detected by mammographic screening and half that they or their clinician had detected it. In polytomous logistic regression models, parity and age at first birth were more strongly associated with risk of mammography-detected breast cancer than with risk of woman/clinician-detected breast cancer (P≤0.01; adjusted for mammography utilization). Among postmenopausal women, estrogen-progestin hormone use was predominantly associated with risk of woman/clinician-detected breast cancer (odds ratio (OR)=1.49, 95% confidence interval (CI): 1.29, 1.72), whereas obesity was predominantly associated with risk of mammography-detected breast cancer (OR=1.72, 95% CI: 1.54, 1.92). Among regularly screened premenopausal women, obesity was not associated with increased risk of mammography-detected breast cancer (OR=0.99, 95% CI: 0.83, 1.18), but it was associated with reduced risk of woman/clinician-detected breast cancer (OR=0.53, 95% CI: 0.43, 0.64). These findings indicate important differences in breast cancer risk factors according to method of detection.

Identification of a common variant with potential pleiotropic effect on risk of inflammatory bowel disease and colorectal cancer

Although genome-wide association studies (GWAS) have separately identified many genetic susceptibility loci for ulcerative colitis (UC), Crohn's disease (CD) and colorectal cancer (CRC), there has been no large-scale examination for pleiotropy, or shared genetic susceptibility, for these conditions. We used logistic regression modeling to examine the associations of 181 UC and CD susceptibility variants previously identified by GWAS with risk of CRC using data from the Genetics and Epidemiology of Colorectal Cancer Consortium and the Colon Cancer Family Registry. We also examined associations of significant variants with clinical and molecular characteristics in a subset of the studies. Among 11794 CRC cases and 14190 controls, rs11676348, the susceptibility single nucleotide polymorphism (SNP) for UC, was significantly associated with reduced risk of CRC (P = 7E-05). The multivariate-adjusted odds ratio of CRC with each copy of the T allele was 0.93 (95% CI 0.89-0.96). The association of the SNP with risk of CRC differed according to mucinous histological features (P heterogeneity = 0.008). In addition, the (T) allele was associated with lower risk of tumors with Crohn's-like reaction but not tumors without such immune infiltrate (P heterogeneity = 0.02) and microsatellite instability-high (MSI-high) but not microsatellite stable or MSI-low tumors (P heterogeneity = 0.03). The minor allele (T) in SNP rs11676348, located downstream from CXCR2 that has been implicated in CRC progression, is associated with a lower risk of CRC, particularly tumors with a mucinous component, Crohn's-like reaction and MSI-high. Our findings offer the promise of risk stratification of inflammatory bowel disease patients for complications such as CRC.

Powerful Set-Based Gene-Environment Interaction Testing Framework for Complex Diseases

Identification of gene-environment interaction (G × E) is important in understanding the etiology of complex diseases. Based on our previously developed Set Based gene EnviRonment InterAction test (SBERIA), in this paper we propose a powerful framework for enhanced set-based G × E testing (eSBERIA). The major challenge of signal aggregation within a set is how to tell signals from noise. eSBERIA tackles this challenge by adaptively aggregating the interaction signals within a set weighted by the strength of the marginal and correlation screening signals. eSBERIA then combines the screening-informed aggregate test with a variance component test to account for the residual signals. Additionally, we develop a case-only extension for eSBERIA (coSBERIA) and an existing set-based method, which boosts the power not only by exploiting the G-E independence assumption but also by avoiding the need to specify main effects for a large number of variants in the set. Through extensive simulation, we show that coSBERIA and eSBERIA are considerably more powerful than existing methods within the case-only and the case-control method categories across a wide range of scenarios. We conduct a genome-wide G × E search by applying our methods to Illumina HumanExome Beadchip data of 10,446 colorectal cancer cases and 10,191 controls and identify two novel interactions between nonsteroidal anti-inflammatory drugs (NSAIDs) and MINK1 and PTCHD3.

A model to determine colorectal cancer risk using common genetic susceptibility loci

BACKGROUND & AIMS

Risk for colorectal cancer (CRC) can be greatly reduced through screening. To aid in the development of screening strategies, we refined models designed to determine risk of CRC by incorporating information from common genetic susceptibility loci.

METHODS

By using data collected from more than 12,000 participants in 6 studies performed from 1990 through 2011 in the United States and Germany, we developed risk determination models based on sex, age, family history, genetic risk score (number of risk alleles carried at 27 validated common CRC susceptibility loci), and history of endoscopic examinations. The model was validated using data collected from approximately 1800 participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, conducted from 1993 through 2001 in the United States.

RESULTS

We identified a CRC genetic risk score that independently predicted which patients in the training set would develop CRC. Compared with determination of risk based only on family history, adding the genetic risk score increased the discriminatory accuracy from 0.51 to 0.59 (P = .0028) for men and from 0.52 to 0.56 (P = .14) for women. We calculated age- and sex-specific 10-year CRC absolute risk estimates based on the number of risk alleles, family history, and history of endoscopic examinations. A model that included a genetic risk score better determined the recommended starting age for screening in subjects with and without family histories of CRC. The starting age for high-risk men (family history of CRC and genetic risk score, 90%) was 42 years, and for low-risk men (no family history of CRC and genetic risk score, 10%) was 52 years. For men with no family history and a high genetic risk score (90%), the starting age would be 47 years; this is an intermediate value that is 5 years earlier than it would be for men with a genetic risk score of 10%. Similar trends were observed in women.

CONCLUSIONS

By incorporating information on CRC risk alleles, we created a model to determine the risk for CRC more accurately. This model might be used to develop screening and prevention strategies.

PIK3CA Somatic Mutation Status in Relation to Patient and Tumor Factors in Racial/Ethnic Minorities with Colorectal Cancer

BACKGROUND

Approximately 10% to 20% of colorectal cancers exhibit somatic mutations in the phosphoinositide-3-kinase, catalytic, alpha polypeptide gene (PIK3CA). We evaluated the relationship of PIK3CA mutation status in colorectal cancer with race/ethnicity, colorectal cancer survival, and other patient and tumor factors.

METHODS

This study comprised 377 racial/ethnic minorities with incident invasive colorectal cancer, enrolled in the Colon Cancer Family Registry via population-based cancer registries. Tumor specimens were tested for PIK3CA mutations in exon 9 and 20 hotspots, BRAF p.V600E mutations, and DNA mismatch repair (MMR). In logistic regression models, we evaluated the association between PIK3CA mutation status and race/ethnicity, overall, and by mutation site. Using Cox regression, we evaluated the association between PIK3CA mutation status and survival after colorectal cancer diagnosis.

RESULTS

PIK3CA mutations were detected in 42 cases (11%), with a similar prevalence across racial/ethnic groups. Individuals with PIK3CA-mutated colorectal cancer were significantly more likely than those with PIK3CA-wildtype disease to have proximal colon cancer, MMR-deficient tumors, and a germline MMR mutation (P ≤ 0.01). There was no evidence for an association between PIK3CA and overall survival (HR, 0.77; 95% confidence interval, 0.43-1.39).

CONCLUSIONS

The prevalence of PIK3CA mutation status in colorectal cancer does not differ according to race/ethnicity, but may vary according to other relevant clinicopathologic and etiologic factors, including germline MMR mutation status, tumor MMR status, and tumor site.

IMPACT

These findings underscore the importance of PIK3CA mutation status in colorectal cancer epidemiology and provide evidence that the prevalence of such mutations is similar across several racial/ethnic groups.