Genetic analyses supporting colorectal, gastric, and prostate cancer syndromes

A Haplotype GWAS in Syndromic Familial Colorectal Cancer

A previous genome-wide association study (GWAS) in colorectal cancer (CRC) patients with gastric and/or prostate cancer in their families suggested genetic loci with a shared risk for these three cancers. A second haplotype GWAS was undertaken in the same colorectal cancer patients and different controls with the aim of confirming the result and finding novel loci. The haplotype GWAS analysis involved 685 patients with colorectal cancer cases and 1642 healthy controls from Sweden. A logistic regression model was used with a sliding window haplotype approach. Whole-genome and exome sequencing datawere used to find candidate SNPs to be tested in a nested case-control study. In the analysis of 685 colorectal cancer cases and 1642 controls, all ten candidate loci from the previous study were confirmed. Fifty candidate loci were suggested with a p-value < 5 × 10-6 and odds ratios between 1.35-6.52. Two of the 50 loci, on 13q33.3 and 16q23.3, were the same as in the previous study. Whole-genome or exome data from 122 colorectal cancer patients was used to search for candidate variants in these 50 loci. A nested case-control study was performed to test genetic variants at 11 loci in a cohort of 827 familial colorectal cancer and a sub-cohort of 293 familial CRC cases with colorectal, gastric, and/or prostate cancer within their families and 1530 healthy controls. One SNP, rs115943733 on 10q11.21, reached statistical significance (OR = 3.26, p = 0.009). Seven SNPs in 4 loci had a higher OR in the smaller cohort compared to the larger study CRC cases. The results in this GWAS gave support for suggested loci with an increased shared risk of CRC, gastric, and/or prostate cancer. Further studies are needed to confirm the shared risk to be able to use this information in cancer prevention.

Candidate Genetic Loci Modifying the Colorectal Cancer Risk Caused by Lifestyle Risk Factors

INTRODUCTION

65%-70% of colorectal cancer (CRC) cases are considered sporadic; they arise under the influence of environmental factors in individuals lacking a family history of CRC. Low-risk genetic variants are believed to contribute to CRC risk, in tandem with lifestyle factors.

METHODS

Six hundred sixteen nonfamilial Swedish CRC cases with at least 1 of the following 5 risk factors: smoking, excessive alcohol consumption, physical inactivity, adherence to an unhealthy diet, and excess body weight were included in this study. A control group consisting of 1,642 healthy individuals was used. Cases and controls were genotyped from blood samples at the Centre for Inherited Disease Research at Johns Hopkins University within the Colorectal Transdisciplinary Study research collaboration, using the Illumina Infinium OncoArray-500 K BeadChip. Five separate genome-wide haplotype association analyses were performed, one for each risk factor. Logistic regression models were used to estimate associations between haplotypes (exposure) and CRC (outcome) in cases with lifestyle risk factors vs controls. Haplotypes with an odds ratio >1 were considered candidate risk markers, denoting an area of interest in the genome. A significance threshold of P < 5 × 10 -8 was used.

RESULTS

We found 17 haplotype regions significantly associated with CRC in cases vs controls. Several regions included genes linked to inflammation and tumor promotion.

DISCUSSION

We concluded that having certain genetic variants was associated with an increased risk of CRC compared with healthy controls among cases with known lifestyle risk factors. The interplay of lifestyle and genetic risk factors calls for further elucidation.

A genome-wide association study in Swedish colorectal cancer patients with gastric- and prostate cancer in relatives

BACKGROUND

A complex inheritance has been suggested in families with colorectal-, gastric- and prostate cancer. Therefore, we conducted a genome-wide association study (GWAS) in colorectal cancer patients, who's relatives had prostate-, and/or gastric cancer.

METHODS

The GWAS analysis consisted of 685 cases of colorectal cancer and 4780 healthy controls from Sweden. A sliding window haplotype analysis was conducted using a logistic regression model. Thereafter, we performed sequencing to find candidate variants, finally to be tested in a nested case-control study.

RESULTS

Candidate loci/genes on ten chromosomal regions were suggested with odds ratios between 1.71-3.62 and p-values < 5 × 10-8 in the analysis. The regions suggested were 1q32.2, 3q29, 4q35.1, 4p15.31, 4q26, 8p23.1, 13q33.3, 13q13.3, 16q23.3 and 22q11.21. All regions, except one on 1q32.2, had protein coding genes, many already shown to be involved in cancer, such as ZDHHC19, SYNPO2, PCYT1A, MYO16, TXNRD2, COMT, and CDH13. Sequencing of DNA from 122 colorectal cancer patients with gastric- and/or prostate cancer in their families was performed to search for candidate variants in the haplotype regions. The identified candidate variants were tested in a nested case-control study of similar colorectal cancer cases and controls. There was some support for an increased risk of colorectal-, gastric-, and/or prostate cancer in all the six loci tested.

CONCLUSIONS

This study demonstrated a proof of principle strategy to identify risk variants found by GWAS, and identified ten candidate loci that could be associated with colorectal, gastric- and prostate cancer.

Comparative analysis of genetic risk scores for predicting biochemical recurrence in prostate cancer patients after radical prostatectomy

BACKGROUND

In recent years, Genome-Wide Association Studies (GWAS) has identified risk variants related to complex diseases, but most genetic variants have less impact on phenotypes. To solve the above problems, methods that can use variants with low genetic effects, such as genetic risk score (GRS), have been developed to predict disease risk.

METHODS

As the GRS model with the most incredible prediction power for complex diseases has not been determined, our study used simulation data and prostate cancer data to explore the disease prediction power of three GRS models, including the simple count genetic risk score (SC-GRS), the direct logistic regression genetic risk score (DL-GRS), and the explained variance weighted GRS based on directed logistic regression (EVDL-GRS).

RESULTS AND CONCLUSIONS

We used 26 SNPs to establish GRS models to predict the risk of biochemical recurrence (BCR) after radical prostatectomy. Combining clinical variables such as age at diagnosis, body mass index, prostate-specific antigen, Gleason score, pathologic T stage, and surgical margin and GRS models has better predictive power for BCR. The results of simulation data (statistical power = 0.707) and prostate cancer data (area under curve = 0.8462) show that DL-GRS has the best prediction performance. The rs455192 was the most relevant locus for BCR (p = 2.496 × 10-6) in our study.

A Swedish Genome-Wide Haplotype Association Analysis Identifies a Novel Breast Cancer Susceptibility Locus in 8p21.2 and Characterizes Three Loci on Chromosomes 10, 11 and 16

(1) Background: The heritability of breast cancer is partly explained but much of the genetic contribution remains to be identified. Haplotypes are often used as markers of ethnicity as they are preserved through generations. We have previously demonstrated that haplotype analysis, in addition to standard SNP association studies, could give novel and more detailed information on genetic cancer susceptibility. (2) Methods: In order to examine the association of a SNP or a haplotype to breast cancer risk, we performed a genome wide haplotype association study, using sliding window analysis of window sizes 1−25 and 50 SNPs, in 3200 Swedish breast cancer cases and 5021 controls. (3) Results: We identified a novel breast cancer susceptibility locus in 8p21.1 (OR 2.08; p 3.92 × 10−8), confirmed three known loci in 10q26.13, 11q13.3, 16q12.1-2 and further identified novel subloci within these three loci. Altogether 76 risk SNPs, 3302 risk haplotypes of window size 2−25 and 113 risk haplotypes of window size 50 at p < 5 × 10−8 on chromosomes 8, 10, 11 and 16 were identified. In the known loci haplotype analysis reached an OR of 1.48 in overall breast cancer and in familial cases OR 1.68. (4) Conclusions: Analyzing haplotypes, rather than single variants, could detect novel susceptibility loci even in small study populations but the method requires a fairly homogenous study population.

Colorectal cancer risk susceptibility loci in a Swedish population

To search for colorectal cancer (CRC) risk loci, Swedish samples were used for a genome-wide haplotype analysis. A logistic regression model was employed in 2663 CRC cases and 1642 controls in the discovery analysis. Three analyses were done, on all, familial-, and nonfamilial CRC samples and only results with odds ratio (OR) > 1 were analyzed. single nucleotide polymorphism (SNP) analysis did not generate any statistically significant results. Haplotype analysis suggested novel loci, on chromosome 2q36.1 (OR = 1.71, p value = 5.6924 × 10^-8 ) in all CRC samples, chromosome 1q43 (OR = 4.04 p value = 3.24 × 10^-8 ) in familial CRC samples, and two hits in nonfamilial CRC samples, chromosomes 2q36.1 (OR = 1.71 p value = 5.69 × 10^-8 ) and 3p24.3 (OR = 1.62 p value = 6.21 × 10^-9 ). Moreover, one locus on chromosome 20q13.33 was suggested in analyses of all samples, and five more novel loci were suggested on chromosomes 10q25.3, 15q,22.31, 17p11.2, 1p34.2, and 3q24. The haplotypes from the analysis of all samples were replicated in a second study of CRC cases and controls from the same part of Sweden. In summary, using haplotype analysis in Swedish CRC samples, the best hits were novel loci and the locus on chromosomes 2q36.1 and 20q13.33 suggested in the analysis of all samples were confirmed in a second cohort. The ORs were often higher than ORs from published genome-wide association study (GWAS). The study suggested it was possible that a risk locus could involve more than one gene, and that haplotypes could give information on the gene or genes possibly involved in the risk at specific locus.

Recent Insights on Genetic Testing in Primary Prostate Cancer

Prostate cancer (PCa) is one of the most common cancers in developed countries. The results of large trials indicate that the proportion of PCa attributable to hereditary factors is as high as 15%, highlighting the importance of genetic testing. Despite improved understanding of the prevalence of pathogenic variants among men with PCa, it remains unclear which men will most benefit from genetic testing. In this review, we summarize recent evidence on genetic testing in primary PCa and its impact on routine clinical practice. We outline current guideline recommendations on genetic testing, most importantly, for mutations in BRCA1/2, MMR, CHEK2, PALB2, and HOXB13 genes, as well as various single nucleotide polymorphisms associated with an increased risk of developing PCa. The implementation of genetic testing in clinical practice, especially in young patients with aggressive tumors or those with positive family history, represents a new challenge for the coming years and will identify men with pathogenic variants who may benefit from early screening/intervention and specific therapeutic options.

An immune-relevant signature of nine genes as a prognostic biomarker in patients with gastric carcinoma

Background

As one of the most common malignant tumors worldwide, the morbidity and mortality of gastric carcinoma (GC) are gradually increasing. The aim of this study was to construct a signature according to immune-relevant genes to predict the survival outcome of GC patients using The Cancer Genome Altas (TCGA).

Methods

Univariate Cox regression analysis was used to assess the relationship between immune-relevant genes regarding the prognosis of patients with GC. The least absolute shrinkage and selection operator (LASSO) Cox regression model was used to select prognostic immune-relevant genes and to establish the signature for the prognostic evaluation of patients with GC. Multivariate Cox regression analysis and Kaplan–Meier survival analysis were used to assess the independent prognostic ability of the immune-relevant gene signature.

Results

A total of 113 prognostic immune-relevant genes were identified using univariate Cox proportional hazards regression analysis. A signature of nine immune-relevant genes was constructed using the LASSO Cox regression. The GC samples were assigned to two groups (low- and high risk) according to the optimal cutoff value of the signature score. Compared with the patients in the high-risk group, patients in the low-risk group had a significantly better prognosis in the TCGA and GSE84437 cohorts (log-rank test P < 0.001). Multivariate Cox regression analysis demonstrated that the signature of nine immune-relevant genes might serve as an independent predictor of GC.

Conclusions

Our results showed that the signature of nine immune-relevant genes may potentially serve as a prognostic prediction for patients with GC, which may contribute to the decision-making of personalized treatment for the patients.

Genetic analyses supporting colorectal, gastric, and prostate cancer syndromes

Colorectal cancer (CRC), prostate cancer (PrC), and gastric cancer (GC) are common worldwide, and the incidence is to a certain extent dependent on genetics. We have recently shown that in families with more than one case of CRC, the risk of other malignancies is increased. We therefore suggested the presence of not yet described CRC syndromes. In this study, we have searched for genetic susceptibility loci for potential cancer syndromes involving CRC combined with PrC and/or GC. We have performed SNP (single-nucleotide polymorphism)-based linkage analyses in 45 families with CRC, PrC, and GC. In the regions with suggested linkage, we performed exome and association haplotype analyses. Five loci generated a high logarithm of odds (HLOD) score >2, suggestive of linkage, in chromosome bands 1q31-32, 1q24-25, 6q25-26, 18p11-q11, and Xp11. Exome analysis detected no potential pathogenic sequence variants. The haplotype association study showed that one of the top five haplotypes with the lowest P value in the chromosome band 6q25 interestingly was found in the family which contributed the most to the increased HLOD at that locus. This study supports a suggested hereditary cancer syndrome involving CRC and PrC and indicates a location at 6q25. The impact of this locus needs to be confirmed in additional studies.