Familial risk of colon and rectal cancer in Iceland: Evidence for different etiologic factors?

Low Incidence of Colorectal Advanced Neoplasia During Surveillance in Individuals with a Family History of Colorectal Cancer

BACKGROUND

Family history of colorectal cancer (CRC) is used to stratify individuals into risk categories which determine timing of initial screening and ongoing CRC surveillance. Evidence for long-term CRC risk following a normal index colonoscopy in family history populations is limited.

AIMS

To assess the incidence of advanced neoplasia and associated risk factors in a population undergoing surveillance colonoscopies due to family history of CRC.

METHODS

Surveillance colonoscopy findings were examined in 425 individuals with a family history of CRC, a normal index colonoscopy and a minimum of 10 years of follow-up colonoscopies. Advanced neoplasia risk was determined for three CRC family history categories (near-average, medium and high-risk), accounting for demographics and time after the first colonoscopy.

RESULTS

The median follow-up was 13.5 years (IQR 11.5-16.0), with an incidence of advanced neoplasia of 14.35% (61/425). The number of affected relatives and age of CRC diagnosis in the youngest relative did not predict the risk of advanced neoplasia (p > 0.05), with no significant differences in advanced neoplasia incidence between the family history categories (p = 0.16). Patients ≥ 60 years showed a fourfold (HR 4.14, 95% CI 1.33-12.89) higher advanced neoplasia risk during surveillance than those < 40 years at index colonoscopy. With each subsequent negative colonoscopy, the risk of advanced neoplasia at ongoing surveillance was reduced.

CONCLUSIONS

The incidence of advanced neoplasia was low (14.35%), regardless of the family history risk category, with older age being the main risk for advanced neoplasia. Delaying onset of colonoscopy or lengthening surveillance intervals could be a more efficient use of resources in this population.

External validation of models for predicting risk of colorectal cancer using the China Kadoorie Biobank

BACKGROUND

In China, colorectal cancer (CRC) incidence and mortality have been steadily increasing over the last decades. Risk models to predict incident CRC have been developed in various populations, but they have not been systematically externally validated in a Chinese population.  This study aimed to assess the performance of risk scores in predicting CRC using the China Kadoorie Biobank (CKB), one of the largest and geographically diverse prospective cohort studies in China.

METHODS

Nine models were externally validated in 512,415 participants in CKB and included 2976 cases of CRC. Model discrimination was assessed, overall and by sex, age, site, and geographic location, using the area under the receiver operating characteristic curve (AUC). Model discrimination of these nine models was compared to a model using age alone. Calibration was assessed for five models, and they were re-calibrated in CKB.

RESULTS

The three models with the highest discrimination (Ma (Cox model) AUC 0.70 [95% CI 0.69-0.71]; Aleksandrova 0.70 [0.69-0.71]; Hong 0.69 [0.67-0.71]) included the variables age, smoking, and alcohol. These models performed significantly better than using a model based on age alone (AUC of 0.65 [95% CI 0.64-0.66]). Model discrimination was generally higher in younger participants, males, urban environments, and for colon cancer. The two models (Guo and Chen) developed in Chinese populations did not perform better than the others. Among the 10% of participants with the highest risk, the three best performing models identified 24-26% of participants that went on to develop CRC.

CONCLUSIONS

Several risk models based on easily obtainable demographic and modifiable lifestyle factor have good discrimination in a Chinese population. The three best performing models have a higher discrimination than using a model based on age alone.

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.

Familial Associations of Colon and Rectal Cancers With Other Cancers

BACKGROUND

Many studies have indicated that colon and rectal cancers differ in etiology and histology.

OBJECTIVE

The aim of this study was to investigate whether the associations of colon and rectal cancers with any other (discordant) cancer were site specific.

DESIGN

A novel approach was implemented in which cancer risks were analyzed in families with increasing numbers of family members diagnosed with defined cancers. The novel assumption was that, for a true familial association, the risk should increase by the number of affected family members. In separate analyses, familial risks were calculated after the exclusion of putative families with hereditary nonpolyposis colorectal cancer.

SETTINGS

The study was conducted using the Swedish Family-Cancer Database.

MAIN OUTCOME MEASURES

The outcome measure was relative risk.

RESULTS

Relative risks of colorectal cancer and colon cancer were higher when family members were diagnosed with colon cancer than when family members were diagnosed with rectal cancer (incidence rate ratio for colorectal: 1.82 (95% CI, 1.74-1.90) vs 1.61 (95% CI, 1.51-1.71); incidence rate ratio for colon: 1.92 (95% CI, 1.83-2.02) vs 1.56 (95% CI, 1.45-1.69)). Relative risks for 10 discordant cancers were increased in colon or rectal cancer families, whereas none of the relative risks differed significantly between colon and rectal cancers. After deleting hereditary nonpolyposis colorectal cancer families, the relative risks of endometrial and ovarian cancers were no longer significant.

LIMITATIONS

Genetic data are unavailable in the database.

CONCLUSIONS

Our results suggested that familial risks for colon cancer were higher than risks for rectal cancer in families of patients with colorectal cancer and colon cancer. The relationships of lung cancer and nervous system cancer with colorectal cancer were site specific. The associations of colon and rectal cancers with lung cancer, myeloma, and cancer of unknown primary appeared not to point out known syndromes and may suggest involvement of a novel predisposition. See Video Abstract at http://links.lww.com/DCR/A791.

Multigenerational information: the example of the Icelandic Genealogy Database

The first part of the chapter describes the Icelandic Genealogical Database, how it was created, what it contains, and how it operates. In the second part, an overview of research accomplished with material from the database is given.

Colon cancer in Iceland--a nationwide comparative study on various pathology parameters with respect to right and left tumor location and patients age

Increasing evidence suggests genetic, biological and demographical difference between right and left colon cancer. Studies have also indicated age differences in the pathology of colon cancer. There is a scarcity of large-scale studies that closely examine the pathological differences regarding age and tumor location. The aim of our study was to do an extensive comparison of right- and left- sided colon cancers as well as comparing patients <50 years with older patients. A retrospective, population-based study was carried out on all patients with colon cancer in Iceland between 1955 and 2004. A total of 2293 cases were analyzed (1148 men, 1145 women). All histopathology material was re-evaluated. Differences in tumor characteristics between right and left location and younger (<50) and older (≥50) patients was evaluated in particular. Higher TNM-stage, larger tumors, vessel invasion, mucinous type, high grade and expanding tumor border occurred more frequently in right- versus left-sided lesions while annular and polypoid tumors were more common in left-sided tumors (p < 0.05). Young patients had more frequent lymph node metastases, vessel invasion, nonpolypoid lesions and infiltrating tumor border (p < 0.05). Right-sided lesions show more aggressive features, reflected in morphology and stage. Younger patients present more frequently with adverse features than do older patients. Frequency of right- and left-sided colon cancer differs by age with pronounced age-location differences in females. This supports the assumption of differences in etiology and carcinogenesis of right- and left-sided colon cancer, and between young and old patients.

Colorectal adenomas and cancer link to chromosome 13q22.1-13q31.3 in a large family with excess colorectal cancer

BACKGROUND

Colorectal cancer is the fourth most common type of cancer and the second most common cause of cancer death. Fewer than 5% of colon cancers arise in the presence of a clear hereditary cancer condition; however, current estimates suggest that an additional 15-25% of colorectal cancers arise on the basis of unknown inherited factors.

AIM

To identify additional genetic factors responsible for colon cancer.

METHODS

A large kindred with excess colorectal cancer was identified through the Utah Population Database and evaluated clinically and genetically for inherited susceptibility.

RESULTS

A major genetic locus segregating with colonic polyps and cancer in this kindred was identified on chromosome 13q with a non-parametric linkage score of 24 (LOD score of 2.99 and p=0.001). The genetic region spans 21 Mbp and contains 27 RefSeq genes. Sequencing of all candidate genes in this region failed to identify a clearly deleterious mutation; however, polymorphisms segregating with the phenotype were identified. Chromosome 13q is commonly gained and overexpressed in colon cancers and correlates with metastasis, suggesting the presence of an important cancer progression gene. Evaluation of tumours from the kindred revealed a gain of 13q as well.

CONCLUSIONS

This identified region may contain a novel gene responsible for colon cancer progression in a significant proportion of sporadic cancers. Identification of the precise gene and causative genetic change in the kindred will be an important next step to understanding cancer progression and metastasis.

The association of tumor microsatellite instability phenotype with family history of colorectal cancer

Family history is a strong predictor of colorectal cancer risk; however, a diagnosis of colorectal cancer among first-degree relatives has not been systematically investigated as a function of the colorectal cancer molecular subtypes related to tumor microsatellite instability (MSI) status. We investigated whether the observable familial colorectal cancer risks differed according to tumor MSI subtypes, stratified as MSI-High (>30% instability), MSI-Low (<30% instability), and MSS (no instability). Data from 3,143 population-based colorectal cancer cases from five institutions were assessed for family history according to the Amsterdam criteria and the Bethesda guidelines, age at diagnosis, sex, tumor location, and MSI status. The distribution of patient characteristics by MSI status was compared using polytomous logistic regression. Overall, 2.8% colorectal cancer cases met the Amsterdam criteria and 37% met the Bethesda guidelines. There were 14% MSI-High, 13% MSI-Low, and 73% MSS colorectal cancers. MSI-High (P<0.0001) and MSI-Low tumors (P=0.01) were more proximally located than MSS tumors. MSI-High tumors were more common among females (P<0.001). The highest proportion of MSI-High tumors occurred in cases<40 years of age whereas the age-dependent distribution of MSI-Low tumors was unchanged. MSI-High tumors showed a statistically significant association with increasing numbers of first-degree relatives with colorectal cancer (P=0.002); this association disappeared, however, when MSI-High cases meeting Amsterdam criteria were removed from the analysis. MSI-Low tumors did not show a similar association with family history of colorectal cancer. Familial risk associated with MSI-High tumors is primarily driven by the Amsterdam-criteria patients. MSI-Low tumors may represent a distinct subtype of colorectal cancer with respect to certain epidemiologic variables studied here.

Association of colorectal adenoma with other malignancies in Swedish families

Using the Swedish Family-Cancer Database covering over 11.5 million individuals, estimated relative risks (RRs) for colorectal adenoma were using Poisson's regression. The RR of colorectal adenoma was found to be increased among first-degree relatives of patients with colorectal cancer (2.72; 95% confidence interval=2.46-3.00) and among the offspring and siblings of patients with endometrial and prostate cancers. We also found an increased risk of colorectal adenoma for the offspring of individuals with stomach cancer and leukaemia, and for siblings of those with pancreatic cancer and multiple myeloma. Our results suggest that colorectal adenoma may share a genetic aetiology with cancer even at extracolorectal sites. Increases of colorectal adenoma in families affected by prostate cancer and acute leukaemia cannot be attributed to known cancer syndromes, although the play of chance cannot be excluded.

Increased cancer risk for individuals with a family history of prostate cancer, colorectal cancer, and melanoma and their associated screening recommendations and practices

Prostate cancer, colorectal cancer, and melanoma are three malignancies that appear to have strong genetic components that can confer additional risk to family members. Screening tools, albeit controversial, are widely available to potentially aide in early diagnosis. Family members are now more attuned to the risks and benefits of cancer screening, thus, it is imperative that physicians understand the screening tools and how to interpret the information they provide. We reviewed the current literature regarding the cancer risks for individuals with a family history of prostate cancer, colon cancer, and melanoma, the current screening recommendations for family members, and actual screening practices of individuals with a family history of these malignancies. This review should serve as a guide for physicians and cancer control planners when advising their patients and the public regarding screening decisions.

The risk of gastrointestinal malignancies in cystic fibrosis: case report of a patient with a near obstructing villous adenoma found on colon cancer screening and Barrett's esophagus

The life expectancy for cystic fibrosis (CF) patients has increased dramatically over the last 30 years. Although the overall cancer risk for CF patients does not appear to be increased there is a marked increased risk of gastrointestinal malignancies especially in the post lung transplant population. CF patients that do develop gastrointestinal malignancies do so at an earlier age and there is often a lag in the diagnosis and management of these individuals. We present a 39 year old male CF patient that underwent a colonoscopy for colon cancer screening and a large, near obstructing, villous adenoma of his ileum was found. The polyp was removed successfully via endoscopy without incident and there was no evidence of malignancy. An upper endoscopy revealed a long segment of Barrett's esophagus with no evidence of dysplasia. We present this case as well as a detailed review of the literature on cancer risk in CF and a discussion of the mechanisms that may be involved. We also present the risk of GI malignancies in non-CF patients as a guide on how to assess and manage the risk of GI malignancies in this ever-changing patient population.

A familial component to human rectal cancer, independent of colon cancer risk

BACKGROUND & AIMS

The Utah Population Database (UPDB) is unique; it links genealogy for over 2 million Utah individuals to a statewide Cancer Registry. We have investigated the familial nature of rectal cancer, considered independently from colon cancer.

METHODS

We estimated relative risks in relatives, and average relatedness among rectal cancer patients using matched controls from the UPDB.

RESULTS

There is a significant increased risk for rectal cancer in first-degree relatives of rectal cancer patients (relative risk [RR], 1.97), equivalent to the risk for colon cancer (RR, 2.11). The significant increased risk for rectal cancer extends to second- and third-degree relatives. The RR for rectal cancer among first-degree relatives of young-onset rectal cancer patients (<55 y), is equivalent (RR, 3.34) to their risk of colon cancer (RR, 3.35).

CONCLUSIONS

The UPDB provides strong evidence for a familial component to rectal cancer that may include a genetic component in addition to shared environment. There is a significant increased risk of rectal cancer in the close and distant relatives of rectal cancer patients, which is even higher among relatives of young-onset patients. Although it has been reported that relatives of colon cancer probands are at increased risk for colorectal cancer, the risk of large-bowel cancer among relatives of rectal cancer patients has been less clear. Relatives of rectal cancer probands experience a risk of cancer of the large bowel that is at least as high as the risk previously reported for relatives of individuals with colon cancer.