Familial relative risk of colorectal cancer: a population-based study

Review article: obesity and colorectal cancer

BACKGROUND

Obesity is a growing global public health problem. More than half the European and North American population is overweight or obese. Colon and rectum cancers are still the second leading cause of cancer death worldwide, and epidemiological data support an association between obesity and colorectal cancers (CRCs).

AIM

To review the literature on CRC epidemiology in obese subjects, assessing the effects of obesity, including childhood or maternal obesity, on CRC, diagnosis, management, and prognosis, and discussing targeted prophylactic measures.

METHOD

We searched PubMed for obesity/overweight/metabolic syndrome and CRC. Other key words included 'staging', 'screening', 'treatment', 'weight loss', 'bariatric surgery' and 'chemotherapy'.

RESULTS

In Europe, about 11% of CRCs are attributed to overweight and obesity. Epidemiological data suggest that obesity is associated with a 30%-70% increased risk of colon cancer in men, the association being less consistent in women. Visceral fat or abdominal obesity seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m² increase in body mass index confers more risk (hazard ratio 1.03). Obesity might increase the likelihood of recurrence or mortality of the primary cancer and may affect initial management, including accurate staging. The risk maybe confounded by different factors, including lower adherence to organised CRC screening programmes. It is unclear whether bariatric surgery helps reduce rectal cancer risk.

CONCLUSIONS

Despite a growing body of evidence linking obesity to CRC, many questions remain unanswered, including whether we should screen patients with obesity earlier or propose prophylactic bariatric surgery for certain patients with obesity.

Familial colorectal cancer

The introduction of average-risk colorectal cancer (CRC) screening programs means that many subjects with family history of CRC and without well-described inherited syndromes can benefit from these public health policies. Therefore, the definition of which individuals should be named under the umbrella of the term "familial CRC" should be reconsidered to include only those who are outside of the protection of population-based screening and need to be moved towards a more intensive surveillance strategy. Two subgroups have been reported as having a high enough CRC risk to be included within the term "familial risk of CRC": individuals who have ≥1 first degree relative (FDR) with CRC diagnosed at age <50 years, and those who have ≥2 FDRs with CRC. Colonoscopy-based screening starting at age 40 years is proposed as the most accepted recommendation for these individuals. Finally, the evolution of Lynch syndrome screening from clinical criteria to tumor tissue analysis and new tools for screening pathogenic gene mutations associated with cancer susceptibility in individuals with early-onset CRC might help to reduce misclassification of familial CRC.

Recent advances in clinical practice: colorectal cancer chemoprevention in the average-risk population

Colorectal cancer (CRC) is one of the most common and lethal malignancies in Western countries. Its development is a multistep process that spans more than 15 years, thereby providing an opportunity for prevention and early detection. The high incidence and mortality rates emphasise the need for prevention and screening. Many countries have therefore introduced CRC screening programmes. It is expected, and preliminary evidence in some countries suggests, that this screening effort will decrease CRC-related mortality rates. CRC prevention involves a healthy lifestyle and chemoprevention-more specifically, oral chemoprevention that can interfere with progression from a normal colonic mucosa to adenocarcinoma. This preventive effect is important for individuals with a genetic predisposition, but also in the general population. The ideal chemopreventive agent, or combination of agents, remains unknown, especially when considering safety during long-term use. This review evaluates the evidence across 80 meta-analyses of interventional and observational studies of CRC prevention using medications, vitamins, supplements and dietary factors. This review suggests that the following factors are associated with a decreased incidence of CRC: aspirin, non-steroidal anti-inflammatory drugs, magnesium, folate, a high consumption of fruits and vegetables, fibre and dairy products. An increased incidence of CRC was observed with frequent alcohol or meat consumption. No evidence of a protective effect for tea, coffee, garlic, fish and soy products was found. The level of evidence is moderate for aspirin, β-carotene and selenium, but is low or very low for all other exposures or interventions.

MicroRNAs for Diagnosis and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide, with high morbidity and mortality rates. The diagnosis and treatment of CRC have the most significant value for disease- free survival. Early diagnosis and early surgical resection are generally considered to be the most effective ways to reduce CRC mortality. In the past few years, many researchers have focused on the role of microRNAs in different tumors, making the functions of microRNAs gradually clear. The present study reviews the role of microRNAs in the diagnosis and treatment of colorectal cancer. Compared with the usual diagnosis methods and biomarker, circulating microRNAs can be promising new effective biomarkers for CRC diagnosis and treatment.

Colorectal cancer risk based on extended family history and body mass index

Family history and body mass index (BMI) are well-known risk factors for colorectal cancer (CRC), however, their joint effects are not well described. Using linked data for genealogy, self-reported height and weight from driver's licenses, and the Utah Surveillance, Epidemiology, and End-Results cancer registry, we found that an increasing number of first-degree relatives (FDR) with CRC is associated with higher standardized incidence ratio (SIR) for overweight/obese probands but not for under/normal weight probands. For probands with two CRC-affected FDRs, the SIR = 1.91 (95% CI [0.52, 4.89]) for under/normal weight probands and SIR = 4.31 (95% CI [2.46, 7.00]) for overweight/obese probands. In the absence of CRC-affected FDRs, any number of CRC-affected SDRs did not significantly increase CRC risk for under/normal weight probands, but for overweight/obese probands with at least three CRC-affected SDRs the SIR = 2.68 (95% CI [1.29, 4.93]). In the absence of CRC-affected FDRs and SDRs, any number of CRC-affected third-degree relatives (TDRs) did not increase risk in under/normal weight probands, but significantly elevated risk for overweight/obese probands with at least two CRC-affected TDRs was observed; SIR = 1.32 (95% CI [1.04, 1.65]). For nonsyndromic CRC, maximum midlife BMI affects risk based on family history and should be taken into account for CRC risk communication when possible.

Effects of Family History on Relative and Absolute Risks for Colorectal Cancer: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Guidelines recommend that individuals with familial colorectal cancer undergo colonoscopy surveillance instead of average-risk screening. However, these recommendations vary widely. To substantiate appropriate surveillance strategies, precise and valid evidence-based risk estimates are needed for individuals with a family history of colorectal cancer (CRC).

METHODS

We systematically searched MEDLINE, EMBASE, and Cochrane from inception to July 2018 for case-control and cohort studies investigating the effect of family history on CRC risk. We calculated summary estimates of pooled relative risks (RRs) using a random-effects model. Life tables were created to convert RR estimates into absolute risk estimates.

RESULTS

We screened 4417 articles and identified 42 eligible case-control and 20 cohort studies. In case-control studies, the RR for CRC in patients with 1 first-degree relative (FDR with CRC) was 1.92 (95% CI, 1.53-2.41) and 1.37 (95% CI, 0.76-2.46) for cohort studies. For individuals with 2 or more FDRs with CRC, the RR was 2.81 in case-control studies (95% CI, 1.73-4.55) and 2.40 in cohort studies (95% CI, 1.76-3.28). For individuals having a FDR diagnosed with CRC at an age younger than 50 years, the RR for CRC in their FDRs was 3.57 in case-control studies (95% CI, 1.07-11.85) and 3.26 in cohort studies (95% CI, 2.82-3.77). The cumulative absolute risks for CRC at 85 years in Western Europe were 4.8% for persons with 1 FDR with CRC (95% CI, 2.7%-8.3%), 8.2% for individuals with 2 or more FDRs (95% CI, 6.1%-10.9%), and 11% for persons with a FDR diagnosed with CRC at an age younger than 50 years (95% CI, 9.5%-12.4%).

CONCLUSIONS

In this systematic review and meta-analysis, we found that the RR of CRC among FDRs is lower than previously expected, especially based on cohort studies. Risk estimates are affected by the number of relatives with CRC and their age at diagnosis. Intensified colonoscopy surveillance strategies could be considered for high-risk groups. PROSPERO trial identification no: CRD42018103058.

Postoperative adjuvant chemotherapy is associated with a lower incidence of colorectal adenomas in patients with previous colorectal cancer

BACKGROUND AND AIMS

The effects of chemotherapeutic agents on the development of colorectal adenomas in patients with previous colorectal cancer (CRC) are not defined. Therefore, we evaluated the potential effect of adjuvant chemotherapy on the incidence of colorectal adenomas in patients with previous CRC.

METHODS

We selected patients with low-risk stage II CRC with or without postoperative 5-fluorouracil-based adjuvant chemotherapy to reduce selection bias. Among 1808 patients with stage II CRC who underwent colonoscopic surveillance after curative resection of CRC between 2006 and 2013, 192 patients were retrospectively enrolled in this study after matching for age and sex. The patients were divided into 96 patients receiving and 96 patients not receiving 5-fluorouracil-based chemotherapy.

RESULTS

Forty patients (41.7%) exhibited colorectal adenomas among 96 patients who received adjuvant chemotherapy, compared with 50 patients (52.1%) with colorectal adenomas among 96 patients who received surgery only. The incidence rate of advanced adenoma was significantly lower in the chemotherapy group than in the nonchemotherapy group (3.1% vs 10.4%, P = .044). After adjustment for clinically relevant factors such as body mass index, aspirin use, metformin use, number of follow-up colonoscopies, and operation type, adjuvant chemotherapy was found to be associated with a decreased incidence of advanced adenoma (odds ratio, .151; 95% confidence interval, .035-.653; P = .011) in patients with stage II CRC.

CONCLUSIONS

The results showed that chemotherapy in patients with CRC may be associated with a lower risk of colorectal advanced adenoma development.

Peroxisome Proliferator-Activated Receptor Gamma in Obesity and Colorectal Cancer: the Role of Epigenetics

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor that is deregulated in obesity. PPARγ exerts diverse antineoplastic effects. Attempting to determine the clinical relevance of the epigenetic mechanisms controlling the expression PPARγ and susceptibility to colorectal cancer (CRC) in obese subjects, this study investigated the role of some microRNAs and DNA methylation on the deregulation of PPARγ. Seventy CRC patients (34 obese and 36 lean), 22 obese and 24 lean healthy controls were included. MicroRNA levels were measured in serum. PPARγ promoter methylation was evaluated in peripheral blood mononuclear cells (PBMC). PPARγ level was evaluated by measuring mRNA level in PBMC and protein level in serum. The tested microRNAs (miR-27b, 130b and 138) were significantly upregulated in obese and CRC patients. Obese and CRC patients had significantly low levels of PPARγ. A significant negative correlation was found between PPARγ levels and the studied microRNAs. There was a significant PPARγ promoter hypermethylation in CRC patients that correlated to low PPARγ levels. Our results suggest that upregulation of microRNAs 27b, 130b and 138 is associated with susceptibility to CRC in obese subjects through PPARγ downregulation. Hypermethylation of PPARγ gene promoter is associated with CRC through suppression of PPARγ regardless of BMI.

Epidemiological Trends in Colorectal Cancer in China: An Ecological Study

BACKGROUND

Due to the changes in lifestyle and dietary behaviors, the incidence of colorectal cancer (CRC) has been rapidly increasing in China.

AIMS

This study is to present the trends of CRC in China over the past decade.

METHODS

It used a series of nationally representative data, including the National Central Cancer Registry of China, the GLOBOCAN project and the Global Burden of Disease.

RESULTS

The age-standardized rate of CRC incidence increased from 12.8 in 2003 to 16.8 per 100,000 in 2011, while the mortality rose from 5.9 to 7.8 per 100,000. The age group most affected by incident CRC cases were those aged 60-74 years old, whereas CRC death was most associated with those >74 years. Furthermore, the east coast of China presented a higher mortality rate (>15 and 10-14.9 per 100,000 in men and women) than central and west China (5-14.9 and 5-9.9 per 100,000). Compared with other countries worldwide, China indicated lower rates of incidence (14.2 per 100,000), mortality (7.4 per 100,000), and 5-year prevalence (52.7 per 100,000) than most developed countries. However, China had a higher case-fatality ratio (14.0 %) and mortality/incidence ratio (52.1 %). Lastly, disability-adjusted life years attributed to CRC in China was 224.2 per 100,000.

CONCLUSIONS

It presents a steady increase in CRC in China over the past decade. It also reveals the domestic diversity of age, gender, and geography and finds the differences between China and developed countries, which may yield insights for national programs and policies.

Family history and the risk of colorectal cancer: The importance of patients' history of colonoscopy

Registry-based studies on the risk of colorectal cancer (CRC) for persons with a family history (FH) typically did not control for important covariates, such as history of colonoscopy. We aimed to quantify the association between FH and CRC risk, carefully accounting for potential confounders. We conducted a population-based case-control study in Germany. A total of 4,313 patients with a first diagnosis of CRC (cases) and 3,153 controls recruited from 2003 to 2014 were included. We used multiple logistic regression analyses to assess the association between FH and risk of CRC with odds ratios (OR) and the resulting 95% confidence intervals (95% CI). A total of 582 cases (13.5%) and 321 (10.2%) controls reported a history of CRC in a first-degree relative, which was associated with a 41% increase in risk of CRC (OR: 1.41, 95% CI 1.22-1.63) after adjustment for sex and age. The OR substantially increased to 1.73 (95% CI, 1.48-2.03) after comprehensive adjustment including previous colonoscopies. Irrespective of their FH status, persons with history of colonoscopies had a lower CRC risk compared with persons without previous colonoscopies and without family history (OR: 0.25, 95% CI, 0.22-0.28 for persons without FH and OR 0.45, 95% CI, 0.36-0.56 for persons with FH). In an era of widespread use of colonoscopy, adjusting for previous colonoscopy is therefore crucial for deriving valid estimates of FH-related CRC risk. Colonoscopy reduces the risk of CRC among those with FH far below levels of people with no FH and no colonoscopy.

Increased Risk of Colorectal Cancer Among Family Members of All Ages, Regardless of Age of Index Case at Diagnosis

BACKGROUND & AIMS

It is not clear whether familial risk of colorectal cancer (CRC) varies with age of index CRC patients or their relatives. We quantified the risk of CRC in first-degree relatives (FDRs), second-degree relatives, and first-cousin relatives of individuals with CRC, stratified by ages and sexes of index patients and ages of relatives.

METHODS

CRCs diagnosed between 1980 and 2010 were identified from the Utah Cancer Registry and linked to pedigrees from the Utah Population Database. Age- and sex-matched CRC-free individuals were selected to form the comparison group. CRC risk in relatives was determined by Cox regression analysis.

RESULTS

Of 18,208 index patients diagnosed with CRC, the highest familial risk was observed in FDRs of index CRC patients who were diagnosed at an age younger than 40 years (hazard ratio [HR], 2.53; 95% confidence interval [CI], 1.7-3.79). However, familial risk was increased in FDRs even when the index case was diagnosed with cancer at an advanced age (>80 years; HR, 1.76; 95% CI, 1.59-1.94). Ages of relatives and ages of index cases of CRC each affected familial cancer risk; the highest risk was found in young relatives (<50 years) of individuals with early-onset CRC (<40 years; HR, 7.0; 95% CI, 2.86-17.09).

CONCLUSIONS

All relatives of individuals with CRC are at increased risk for this cancer, regardless of the age of diagnosis of the index patient. Although risk is greatest among young relatives of early-onset CRC cases, relatives of patients diagnosed at advanced ages also have an increased risk.

Incidence and mortality of colorectal cancer in individuals with a family history of colorectal cancer

BACKGROUND & AIMS

Little is known about the change in risk conferred by family history of colorectal cancer (CRC) as a person ages. We evaluated the effect of family history on CRC incidence and mortality after 55 years of age, when the risk of early onset cancer had passed.

METHODS

We collected data from participants in the randomized, controlled Prostate, Lung, Colorectal and Ovarian cancer screening trial of flexible sigmoidoscopy versus usual care (55-74 years old, no history of CRC), performed at 10 US centers from 1993 to 2001. A detailed family history of colorectal cancer was obtained at enrollment, and subjects were followed for CRC incidence and mortality for up to 13 years.

RESULTS

Among 144,768 participants, 14,961 subjects (10.3%) reported a family of CRC. Of 2090 incident cases, 273 cases (13.1%) had a family history of CRC; among 538 deaths from CRC, 71 (13.2%) had a family history of CRC. Overall, family history of CRC was associated with an increased risk of CRC incidence (hazard ratio [HR], 1.30; 95% confidence interval [CI], 1.10-1.50; P<.0001) and increased mortality (HR, 1.31; 95% CI, 1.02-1.69; P = .03). Subjects with 1 first degree relative (FDR) with CRC (n = 238; HR, 1.23; 95% CI, 1.07-1.42) or ≥2 FDRs with CRC (n = 35; HR, 2.04; 95% CI, 1.44-2.86) were at increased risk for incident CRC. However, among individuals with 1 FDR with CRC, there were no differences in risk based on age at diagnosis in the FDR (for FDR <60 years of age: HR, 1.27; 95% CI, 0.97-1.63; for FDR 60-70 years of age: HR, 1.33; 95% CI, 1.06-1.62; for FDR >70 years of age: HR, 1.14; 95% CI, 0.93-1.45; P trend = .59).

CONCLUSIONS

After 55 years of age, subjects with 1 FDR with CRC had only a modest increase in risk for CRC incidence and death; age of onset in the FDR was not significantly associated with risk. Individuals with ≥2 FDRs with CRC had continued increased risk in older age. Guidelines and clinical practice for subjects with a family history of CRC should be modified to align CRC testing to risk. ClinicalTrials.gov number, NCT00002540.

MethyLight droplet digital PCR for detection and absolute quantification of infrequently methylated alleles

Aberrant DNA methylation is a common epigenetic alteration found in colorectal adenomas and cancers and plays a role in cancer initiation and progression. Aberrantly methylated DNA loci can also be found infrequently present in normal colon tissue, where they seem to have potential to be used as colorectal cancer (CRC) risk biomarkers. However, detection and precise quantification of the infrequent methylation events seen in normal colon is likely beyond the capability of commonly used PCR technologies. To determine the potential for methylated DNA loci as CRC risk biomarkers, we developed MethyLight droplet digital PCR (ddPCR) assays and compared their performance to the widely used conventional MethyLight PCR. Our analyses demonstrated the capacity of MethyLight ddPCR to detect a single methylated NTRK3 allele from among more than 3125 unmethylated alleles, 25-fold more sensitive than conventional MethyLight PCR. The MethyLight ddPCR assay detected as little as 19 and 38 haploid genome equivalents of methylated EVL and methylated NTRK3, respectively, which far exceeded conventional MethyLight PCR (379 haploid genome equivalents for both genes). When assessing methylated EVL levels in CRC tissue samples, MethyLight ddPCR reduced coefficients of variation (CV) to 6-65% of CVs seen with conventional MethyLight PCR. Importantly, we showed the ability of MethyLight ddPCR to detect infrequently methylated EVL alleles in normal colon mucosa samples that could not be detected by conventional MethyLight PCR. This study suggests that the sensitivity and precision of methylation detection by MethyLight ddPCR enhances the potential of methylated alleles for use as CRC risk biomarkers.

Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers therapy and colorectal cancer: a systematic review and meta-analysis

PURPOSE

We aim to investigate the association between angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) therapy and colorectal cancer (CRC) by conducting a systematic review with meta-analysis.

METHODS

Literature was searched on PubMed, Scopus, and the Cochrane library to identify relevant studies evaluating ACEIs/ARBs therapy and risk of CRC incidence or survival of CRC patients. Pooled risk ratio (RR) with 95% confidence intervals was calculated for the association between ACEIs/ARBs and CRC risk and mortality.

RESULTS

Eleven observational studies were included in the systematic review. A meta-analysis of six studies totaling 113,048 individuals indicated a 6% decreased risk of CRC in ACEIs/ARBs users compared to non-users (95% CI 0.89-0.98). In the four case-control studies, individuals using ACEIs/ARBs were associated with a 6% decreased risk of CRC (95% CI 0.90-0.99). The meta-analysis of three studies investigating the relationship between ACEIs/ARBs and survival of CRC did not show a significantly decreased mortality in ACEIs/ARBs users (RR 0.81, 95% CI 0.60-1.09). Seven studies evaluated the dose-response relationship between ACEIs/ARBs therapy and CRC, and two of them showed that the association was related to longer duration and higher dose.

CONCLUSIONS

CEIs/ARBs therapy might be associated with a reduce risk of CRC development, but whether use of these medications improves the outcomes of CRC remains unknown. Large-scale and more robust studies are needed to further explore this association.

Increased risk of colorectal neoplasia among family members of patients with colorectal cancer: a population-based study in Utah

BACKGROUND & AIMS

Colorectal cancer (CRC) frequently develops in multiple members of the same families, but more data are needed to prepare effective screening guidelines. We quantified the risk of CRC and adenomas in first-degree relatives (FDRs) and second-degree relatives and first cousins of individuals with CRC, and stratified risk based on age at cancer diagnosis.

METHODS

We performed a case-control study of Utah residents, 50-80 years old, who underwent colonoscopy from 1995 through 2009. Index cases (exposed to colonoscopy) were colonoscopy patients with a CRC diagnosis. Age- and sex-matched individuals, unexposed to colonoscopy (controls) were selected to form the comparison groups for determining risk in relatives. Colonoscopy results were linked to cancer and pedigree information from the Utah Population Database to investigate familial aggregation of colorectal neoplasia using Cox regression analysis.

RESULTS

Of 126,936 patients who underwent a colonoscopy, 3804 were diagnosed with CRC and defined the index cases. FDRs had an increased risk of CRC (hazard rate ratio [HRR], 1.79; 95% confidence interval [CI],1.59-2.03), as did second-degree relatives (HRR, 1.32; 95% CI, 1.19-1.47) and first cousins (HRR, 1.15; 95% CI, 1.07-1.25), compared with relatives of controls. This risk was greater for FDRs when index patients developed CRC at younger than age 60 years (HRR, 2.11; 95% CI, 1.70-2.63), compared with older than age 60 years (HRR, 1.77; 95% CI, 1.58-1.99). The risk of adenomas (HRR, 1.82; 95% CI, 1.66-2.00) and adenomas with villous histology (HRR, 2.43; 95% CI, 1.96-3.01) also were increased in FDRs. Three percent of CRCs in FDRs would have been missed if the current guidelines, which stratify screening recommendations by the age of the proband, were strictly followed.

CONCLUSIONS

FDRs, second-degree relatives, and first cousins of patients who undergo colonoscopy and are found to have CRC have a significant increase in the risk of colorectal neoplasia. These data should be considered when establishing CRC screening guidelines for individuals and families.

Republished: obesity and colorectal cancer

Excess body weight, as defined by the body mass index (BMI), has been associated with several diseases and includes subjects who are overweight (BMI≥25-29.9 kg/m(2)) or obese (BMI≥30 kg/m(2)). Overweight and obesity constitute the fifth leading risk for overall mortality, accounting for at least 2.8 million adult deaths each year. In addition around 11% of colorectal cancer (CRC) cases have been attributed to overweight and obesity in Europe. Epidemiological data suggest that obesity is associated with a 30-70% increased risk of colon cancer in men, whereas the association is less consistent in women. Similar trends exist for colorectal adenoma, although the risk appears lower. Visceral fat, or abdominal obesity, seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m(2) increase in BMI confers additional risk (HR 1.03). Obesity might be associated with worse cancer outcomes, such as recurrence of the primary cancer or mortality. Several factors, including reduced sensitivity to antiangiogenic-therapeutic regimens, might explain these differences. Except for wound infection, obesity has no significant impact on surgical procedures. The underlying mechanisms linking obesity to CRC are still a matter of debate, but metabolic syndrome, insulin resistance and modifications in levels of adipocytokines seem to be of great importance. Other biological factors such as the gut microbita or bile acids are emerging. Many questions still remain unanswered: should preventive strategies specifically target obese patients? Is the risk of cancer great enough to propose prophylactic bariatric surgery in certain patients with obesity?

Significant SNPs have limited prediction ability for thyroid cancer

Recently, five thyroid cancer significantly associated genetic variants (rs965513, rs944289, rs116909374, rs966423, and rs2439302) have been discovered and validated in two independent GWAS and numerous case–control studies, which were conducted in different populations. We genotyped the above five single nucleotide polymorphisms (SNPs) in Han Chinese populations and performed thyroid cancer-risk predictions with nine machine learning methods. We found that four SNPs were significantly associated with thyroid cancer in Han Chinese population, while no polymorphism was observed for rs116909374. Small familial relative risks (1.02–1.05) and limited power to predict thyroid cancer (AUCs: 0.54–0.60) indicate limited clinical potential. Four significant SNPs have limited prediction ability for thyroid cancer.

Mechanisms linking excess adiposity and carcinogenesis promotion

Obesity constitutes one of the most important metabolic diseases being associated to insulin resistance development and increased cardiovascular risk. Association between obesity and cancer has also been well established for several tumor types, such as breast cancer in post-menopausal women, colorectal, and prostate cancer. Cancer is the first death cause in developed countries and the second one in developing countries, with high incidence rates around the world. Furthermore, it has been estimated that 15-20% of all cancer deaths may be attributable to obesity. Tumor growth is regulated by interactions between tumor cells and their tissue microenvironment. In this sense, obesity may lead to cancer development through dysfunctional adipose tissue and altered signaling pathways. In this review, three main pathways relating obesity and cancer development are examined: (i) inflammatory changes leading to macrophage polarization and altered adipokine profile; (ii) insulin resistance development; and (iii) adipose tissue hypoxia. Since obesity and cancer present a high prevalence, the association between these conditions is of great public health significance and studies showing mechanisms by which obesity lead to cancer development and progression are needed to improve prevention and management of these diseases.

Metformin use is associated with a decreased incidence of colorectal adenomas in diabetic patients with previous colorectal cancer

BACKGROUND

Metformin use has been associated with decreased cancer risk and mortality. However, the effects of metformin on the development of colorectal adenomas, the precursors of colorectal cancers, are not defined.

AIMS

This study aimed to evaluate the potential effect of metformin on the incidence of colorectal adenomas in diabetic patients with previous colorectal cancer.

METHODS

Among 488 consecutive diabetic patients who underwent colonoscopic surveillance after curative resection of colorectal cancer between 1998 and 2008, 240 patients were enrolled in this study and were compared in two groups: 114 patients taking metformin and 126 patients not taking metformin. Patient demographics, clinical characteristics, and colorectal adenoma incidence rate were analysed.

RESULTS

After a median follow-up of 58 months, a total of 33 patients (28.9%) exhibited adenomatous colorectal polyps among the 114 patients who used metformin, compared with 58 (46.0%) patients with colorectal adenomas among the 126 patients who did not use metformin (odds ratio = 0.48, 95% confidence interval = 0.280-0.816, P = 0.008). After adjustment for clinically relevant factors, metformin use was found to be associated with a decreased incidence of colorectal adenomas (odds ratio = 0.27, 95% confidence interval = 0.100-0.758, P = 0.012) in diabetic patients with previous colorectal cancer. Metformin use in diabetic patients with previous colorectal cancer is associated with a lower risk of colorectal adenoma.

Gamma Tocopherol and Lovastatin Additively Induced Apoptosis in Human Colorectal Carcinoma Cell Line (HT29)

BACKGROUND

Programmed cell death (apoptosis) is a physiological process needed to remove unwanted or damaged cells. It has been hypothesized that any failure of programmed cell death leads to the development of neoplasm. Identifying new agents which induce apoptosis in tumor cells is of great significance in treatment of neoplasms. Numerous studies suggest that exposure of tumor cells to statins and gamma tocopherol can lead to cell death.

OBJECTIVES

The aim of this study was to evaluate the cell death induced by gamma tocopherol and lovastatin in human colorectal carcinoma cell line (HT29) using flow cytometry.

MATERIAL AND METHODS

HT29 cells were grown in DMEM medium, exposed to different concentrations of lovastatin (10,20,40,100μM ) and gamma tocopherol (25,50,100,200μM) for 48 and 72 hours, individually and in combination (100μM both, 48 h). Phenotype of apoptosis was determined by means of flow cytometry.

RESULTS

All Concentrations of lovastatin (10, 20, 40, 100 μM) and gamma tocopherol (25, 50, 100, 200 μM) induced an apoptotic response in HT29 cells. In combination, a significant increase in apoptosis phenotype was also demonstrated (P < 0.05).

CONCLUSIONS

This study showed that lovastatin when combined with gamma tocopherol, could induce apoptosis in HT29 cells more potently than each agent alone, which uncovers the significance of targeting the proliferative signaling in different points of the pathway.

Variants in the netrin-1 receptor UNC5C prevent apoptosis and increase risk of familial colorectal cancer

BACKGROUND & AIMS

Expression of the netrin-1 dependence receptor UNC5C is reduced in many colorectal tumors; mice with the UNC5C mutations have increased progression of intestinal tumors. We investigated whether specific variants in UNC5C increase risk of colorectal cancer (CRC).

METHODS

We analyzed the sequence of UNC5C in blood samples from 1801 patients with CRC and 4152 controls from 3 cohorts (France, United States, and Finland). Almost all cases from France and the United States had familial CRC; of the Finnish cases, 92 of 984 were familial. We analyzed whether CRC segregates with the UNC5C variant A628K in 3 families with histories of CRC. We also performed haplotype analysis to determine the origin of this variant.

RESULTS

Of 817 patients with familial CRC, 14 had 1 of 4 different, unreported missense variants in UNC5C. The variants p.Asp353Asn (encodes D353N), p.Arg603Cys (encodes R603C), and p.Gln630Glu (encodes Q630E) did not occur significantly more often in cases than controls. The variant p.Ala628Lys (A628K) was detected in 3 families in the French cohort (odds ratio, 8.8; Wald's 95% confidence interval, 1.47-52.93; P = .03) and in 2 families in the US cohort (odds ratio, 1.9; P = .6) but was not detected in the Finnish cohort; UNC5C A628K segregated with CRC in families. Three families with A628K had a 109-kilobase identical haplotype that spanned most of UNC5C, indicating recent origin of this variant in white subjects (14 generations; 95% confidence interval, 6-36 generations). Transfection of HEK293T cells with UNC5C-A628K significantly reduced apoptosis compared with wild-type UNC5C, measured in an assay of active caspase-3.

CONCLUSIONS

Inherited mutations in UNC5C prevent apoptosis and increase risk of CRC.

A telematic tool to predict the risk of colorectal cancer in white men and women: ColoRectal Cancer Alert (CRCA)

Colorectal cancer is an important disease because of its severity and also since it affects much of the population. Nothing helps patients and doctors to determine the risk of suffering from colorectal cancer during their lives, except for medical tests such as the colonoscopy. There have been several studies and research to try to estimate the relative risks of colorectal cancer based on various factors and the applications to calculate the risk of this cancer, but these are not within everyone's research. This project offers a multilingual Web tool, called ColoRectal Cancer Alert (CRCA), to calculate the risk of colorectal cancer for life in men and women of white race. With this application, doctors can carry out research in a few minutes to explore this risk when they are seeing a patient. The platform is designed in such a way that anyone can use it. It is easy to use and intuitive. We should keep in mind that this tool does not replace diagnostic tests such as the colonoscopy or the sigmoidoscopy. It is designed so that users with the assistance of their doctor know the risk and act accordingly (for example, having more checkups on the disease in case of high risk). To access the tool a computer with Internet connection will be required. Currently, 250 users of white race under the supervision of a specialist have completed the questionnaire.

Individual cancer risk as a function of current age and risk profile

Behavioural changes are an important partner in the fight against cancer (primary prevention or the choice to participate in secondary prevention). To make such behavioural changes, people need to have a correct assessment of their own risk, which is often underestimated or overestimated. These risk estimates depend, among others, on the calculation method that is used. Currently, the method that is used most often is 'indirect cumulative risk' (ICR). We discuss several drawbacks of using ICR in individual counselling and therefore use an alternative method. In this alternative (life table method) we calculated 10-year risks for a whole range of cancers as a function of the current age and risk profile, while taking into account other causes of death. These estimates can easily be used to give an individualized assessment of the risk of cancer. Regardless of the risk estimation method used, the risk needs to be broken down for 'risk factors'. If only the risk for an average person of the population is given, this means a small overestimation for the non-risk group, but a significant underestimation for the at-risk group. When we compare the life table risk as a function of risk factors to the more commonly used ICR, large differences are found, especially in prostate, breast and lung carcinomas. The life table method, although it has certain limitations, has advantages over the ICR method for individual counselling. To our knowledge this is the first overview in which 10-year risks as a function of the current risk profile are given for multiple cancers. The calculated risks are primarily intended to better inform people who are considering preventive measures. For example, for a 40-year-old woman without familial risk who is considering the pros and cons of breast cancer mammographic screening, it is more interesting to know that she has a 0.7% chance of getting breast cancer in the next 5 years, rather than being told that 11% of women get breast cancer during their lives (ICR 0-74). Current smokers can now be given absolute risk reduction estimates of smoking cessation. To keep the life table risk estimates up to date, they must be repeated every couple of years, using up-to-date incidence and mortality data.

Investigation of innate immunity genes CARD4, CARD8 and CARD15 as germline susceptibility factors for colorectal cancer

Background

Variation in genes involved in the innate immune response may play a role in the predisposition to colorectal cancer (CRC). Several polymorphisms of the CARD15 gene (caspase activating recruitment domain, member 15) have been reported to be associated with an increased susceptibility to Crohn disease. Since the CARD15 gene product and other CARD proteins function in innate immunity, we investigated the impact of germline variation at the CARD4, CARD8 and CARD15 loci on the risk for sporadic CRC, using a large patient sample from Northern Germany.

Methods

A total of 1044 patients who had been operated with sporadic colorectal carcinoma (median age at diagnosis: 59 years) were recruited and compared to 724 sex-matched, population-based control individuals (median age: 68 years). Genetic investigation was carried out following both a coding SNP and haplotype tagging approach. Subgroup analyses for N = 143 patients with early manifestation of CRC (≤50 age at diagnosis) were performed for all CARD loci and subgroup analyses for diverse age strata were carried out for CARD15 mutations R702W, G908R and L1007fs. In addition, all SNPs were tested for association with disease presentation and family history of CRC.

Results

No significant differences were observed between the patient and control allelic or haplotypic spectra of the three genes under study for the total cohort (N = 1044 patients). None of the analysed SNPs was significantly associated with either tumour location or yielded significant association in the familial or non-familial CRC patient subgroups. However, in a patient subgroup (≤45 age at diagnosis) with early disease manifestation the mutant allele of CARD15 R702W was found to be significantly associated with disease susceptibility (9.7% in cases vs 4.6% in controls; P_allelic = 0.008, P_genotypic = 0.0008, OR_allelic = 2.22 (1.21-4.05) OR_ressessive = 21.9 (1.96-245.4).

Conclusion

Variation in the innate immunity genes CARD4, CARD8 and CARD15 is unlikely to play a major role in the susceptibility to CRC in the German population. But, we report a significant disease contribution of CARD15 for CRC patients with very early disease manifestation, mainly driven by variant R702W.

Investigation of the colorectal cancer susceptibility region on chromosome 8q24.21 in a large German case-control sample

Human chromosome 8q24.21 has been implicated as a susceptibility region for colorectal cancer (CRC) as a result of genome-wide association and candidate gene studies. To assess the impact of molecular variants at 8q24.21 upon the CRC risk of German individuals and to refine the disease-associated region, a total of 2,713 patients with operated CRC (median age at diagnosis: 63 years) were compared with 2,718 sex-matched control individuals (median age at inclusion: 65 years). Information on microsatellite instability in tumors was available for 901 patients. Association analysis of SNPs rs10505477 and rs6983267 yielded allelic p-values of 1.42 x 10(-7) and 2.57 x 10(-7), respectively. For both polymorphisms, the odds ratio was estimated to be 1.50 (95% CI: 1.29-1.75) under a recessive disease model. The strongest candidate interval, outside of which significance dropped by more than 4 orders of magnitude, was delineated by SNPs rs10505477 and rs7014346 and comprised 17 kb. In a subgroup analysis, the disease association was found to be more pronounced in MSI-stable tumors (odds ratio: 1.71). Our study confirms the role of genetic variation at 8q24.21 as a risk factor for CRC and localizes the corresponding susceptibility gene to a 17 kb candidate region.

Genetic investigation of DNA-repair pathway genes PMS2, MLH1, MSH2, MSH6, MUTYH, OGG1 and MTH1 in sporadic colon cancer

Mutations in DNA repair genes have previously been identified as causative factors for hereditary nonpolyposis colon cancer (HNPCC). Recent evidence also supports an association between DNA sequence variation in these genes and sporadic colorectal carcinoma (CRC). Genetic investigation of DNA repair genes PMS2, MLH1, MSH2, MSH6, MUTYH, OGG1 and MTH1, as possible susceptibility factors for sporadic CRC, was done using both a haplotype tagging and a candidate (i.e. coding) single nucleotide polymorphism (SNP) approach. Some 1,068 patients with operated CRC (median age at diagnosis: 59 years) were compared to 738 sex-matched control individuals (median age: 67 years). Haplotype tagging SNPs, previously reported risk variants and all known coding SNPs with a minor allele frequency >0.005 were genotyped in PMS2 (N = 10), MLH1 (N = 11), MSH2 (N = 18), MSH6 (N = 15), MUTYH (N = 7), OGG1 (N = 11) and MTH1 (N = 3). No evidence for an association between CRC and any of the 7 genes was detected, neither with the tagging or coding SNPs nor in a sliding window haplotype analysis (all nominal p-values >0.05). The previously reported risk variants D132H in MLH1 and R154H in OGG1 were not even observed in the German population. Genetic CRC risk factors so far identified in DNA repair genes seem to be rare and population-specific. Their association with the disease could not be replicated in German CRC samples. It remains to be elucidated by more systematic, large-scale experiments whether common variants in the same genes, but present across populations, represent risk factors for sporadic CRC.

[Identification and management of HNPCC syndrome (hereditary non polyposis colon cancer), hereditary predisposition to colorectal and endometrial adenocarcinomas]

BACKGROUND

The HNPCC syndrome (hereditary nonpolyposis colon cancer) is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for small intestine, urothelial, ovary, stomach and biliary tract carcinomas. HNPCC syndrome is responsible for 5% of colorectal cancers. Identification and management of this disease are part of a multidisciplinary procedure.

METHODS

Twelve experts have been mandated by the French Health Ministry to analyze and synthesize their consensus position, and the resulting document has been reviewed by an additional group of 4 independent experts.

MAIN RECOMMENDATIONS

The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a 2-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases. The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks, but other organs being at low lifetime risk, no specific surveillance will be proposed.

Measures of familial aggregation depend on definition of family history: meta-analysis for colorectal cancer

OBJECTIVE

Familial aggregation, a primary theme in genetic epidemiology, can be estimated from family studies based on an index person. The excess risk due to the presence of affected family members can be classified according to whether disease in the relatives is considered a risk factor for the index person (type I relative risk) or whether the disease status of the index person is considered a risk factor for the relatives (type II relative risk).

STUDY DESIGN AND SETTING

A meta-analysis of published colorectal cancer studies reporting a measure of familial association was performed and application of multilevel linear regression to model age-specific relative risks presented.

RESULTS

The pooled type I relative risk of colorectal cancer given any affected first-degree relative (based on 20 studies) was 2.26 (95% confidence interval CI = 1.86, 2.73) and decreased with the age of the consultand. The pooled type II estimate (based on seven studies) was 2.81 (95% CI = 2.05, 3.85).

CONCLUSION

Type I relative risks are useful in clinical counseling settings when a consultand wants to know his/her disease risk given his or her family history. Type II relative risks can be used to quantify the risk of disease to relatives of an affected individual and then identify subjects eligible for screening.

Relative and absolute risk of colorectal cancer for individuals with a family history: A meta-analysis

Accurate risk estimates for individuals with a family history of colorectal cancer are important for surveillance strategies. We systematically reviewed the literature on familial risks of colorectal cancer to determine relative risk estimates for categories of family history and translated these relative risk estimates into absolute risk estimates. A random-effects meta-analysis pooled the effect estimates from individual studies and actuarial life-table methods converted relative into absolute risks. Fifty-nine studies were identified including 47 that estimated the relative risk of developing colorectal cancer given at least one affected first-degree relative. The pooled risk estimate was 2.24 (95% CI 2.06 to 2.43) which rose to 3.97 (95% CI 2.60 to 6.06) with at least two affected relatives. A population lifetime risk of 1.8% for a 50-year old increased to 3.4% (95% CI 2.8 to 4.0) with at least one affected relative or 6.9% (95% CI 4.5 to 10.4) with two or more. Accurate absolute risk estimates show how cancer risks vary over time, particularly by pattern of family history and age of individual at-risk.

Review article: the potential of combinational regimen with non-steroidal anti-inflammatory drugs in the chemoprevention of colorectal cancer

Non-steroidal anti-inflammatory drugs are chemopreventive agents in colorectal cancer. Non-steroidal anti-inflammatory drugs do not, however, offer complete protection against adenoma and carcinoma development. There is increasing interest in combining non-steroidal anti-inflammatory drugs with agents that target specific cell signalling pathways in malignant and premalignant cells. This review aims to describe the current knowledge regarding the efficacy of peroxisome proliferator-activated receptor-gamma ligands, cholesterol synthesis inhibitors (statins), epidermal growth factor signalling inhibitors and tumour necrosis factor-related apoptosis-inducing ligand against colorectal neoplasms and the rationale for combining these drugs with non-steroidal anti-inflammatory drugs to improve efficacy in the chemoprevention of colorectal cancer, a PUBMED computer search of the English language literature was conducted to identify relevant papers published before July 2004. Peroxisome proliferator-activated receptor-gamma ligands and statins, both in clinical use, reduce the growth rate of human colon cancer cells in vitro and in rodents models. In vitro, preclinical in vivo and clinical studies have shown efficacy of epidermal growth factor signalling inhibition in colorectal cancer. In vitro, tumour necrosis factor-related apoptosis-inducing ligand induces apoptosis in human colon cancer cells, but not in normal cells. These drugs have all been shown to interact with non-steroidal anti-inflammatory drugs in colorectal cancer cells and/or in rodent models. Combinational regimen are a promising strategy for the chemoprevention of colorectal cancer and should be further explored.

Le syndrome HNPCC (hereditary non polyposis colon cancer) : identification et prise en charge

BACKGROUND

The hereditary non-polyposis colon cancer (HNPCC) syndrome is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for other organs tumors. HNPCC syndrome is responsible for 5% of colorectal cancers.

MAJOR ASPECTS

The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a two-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases.

FURTHER DEVELOPMENTS

The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks; other organs being at low lifetime risk, no specific surveillance will be proposed.