Cancer as a complex phenotype: pattern of cancer distribution within and beyond the nuclear family

Novel insights into the biology of CLL

Significant advancements in the care of patients with chronic lymphocytic leukemia (CLL) have occurred over the past decade. Nonetheless, CLL remains incurable outside of allogeneic transplantation. CLL is the most common leukemia in the United States and Europe, and new treatments and therapeutic strategies are clearly needed. To address this need, the pathogenesis of CLL has been an area of intense ongoing investigation. These international efforts illuminate a complex biology that is reliant on the interplay of inherited, environmental, and host factors. This broad review will discuss the recent advances in our understanding of CLL biology including the elucidation of inherited and acquired genetic changes; the role of the B-cell receptor and B-cell receptor signaling; CLL cell kinetics; and the interactions in the microenvironment between CLL cells, other immune cells, and stromal elements. This improved understanding of disease pathogenesis is facilitating the development of novel therapeutic treatment strategies.

Increased Prevalence of Precursor Lesions in Familial Pancreatic Cancer Patients

PURPOSE: Histologic findings in 51 pancreata resected from patients with a strong family history of pancreatic cancer were compared with the findings in 40 pancreata resected from patients with sporadic pancreatic cancer. None of the patients in the familial group had a known inherited syndrome other than familial pancreatic cancer. EXPERIMENTAL DESIGN: Precursor lesions, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and incipient IPMN, were quantified. Invasive cancers were classified using established histologic criteria. RESULTS: The individual precursor lesions identified in both groups were histologically similar. Precursor lesions were more common in the familial cases than in the sporadic cases. The relative rate of PanINs per square centimeter was 2.75-fold higher (95% confidence interval, 2.05-3.70; adjusted for age) in familial compared with sporadic cases. PanIN-3 lesions were more common in familial versus sporadic pancreatic cancer patients (relative rate, 4.20; 95% confidence interval, 2.22-7.93; adjusted for age). High-grade incipient IPMNs were only observed in the familial cases. Nine of the 51 (18%) familial pancreatic cancers and 4 of the 40 (10%) sporadic cancers arose in association with an IPMN. No significant differences were found in the types of invasive cancers. CONCLUSIONS: Noninvasive precursor lesions are more common in patients with a strong family history of pancreatic cancer than in patients with sporadic disease, and precursor lesions are of a higher grade in patients with a strong family history of pancreatic cancer. These findings can form a basis for the design of screening tests for the early detection of pancreatic neoplasia. (Clin Cancer Res 2009;15(24):7737-43).

Genetic basis of tooth agenesis

Tooth agenesis or hypodontia, failure to develop all normally developing teeth, is one of the most common developmental anomalies in man. Common forms, including third molar agenesis and hypodontia of one or more of the incisors and premolars, constitute the great majority of cases. They typically affect those teeth that develop latest in each tooth class and these teeth are also most commonly affected in more severe and rare types of tooth agenesis. Specific vulnerability of the last developing teeth suggests that agenesis reflects quantitative defects during dental development. So far molecular genetics has revealed the genetic background of only rare forms of tooth agenesis. Mutations in MSX1, PAX9, AXIN2 and EDA have been identified in familial severe agenesis (oligodontia) and mutations in many other genes have been identified in syndromes in which tooth agenesis is a regular feature. Heterozygous loss of function mutations in many genes reduce the gene dose, whereas e.g. in hypohidrotic ectodermal dysplasia (EDA) the complete inactivation of the partially redundant signaling pathway reduces the signaling centers. Although these mechanisms involve quantitative disturbances, the phenotypes associated with mutations in different genes indicate that in addition to an overall reduction of odontogenic potential, tooth class-specific and more complex mechanisms are also involved. Although several of the genes so far identified in rare forms of tooth agenesis are being studied as candidate genes of common third molar agenesis and incisor and premolar hypodontia, it is plausible that novel genes that contribute to these phenotypes will also become identified.

Familial risk for common diseases in primary care: the Family Healthware Impact Trial

CONTEXT

Family history is a risk factor for many common chronic diseases, yet it remains underutilized in primary care practice.

BACKGROUND

Family Healthware is a self-administered, web-based tool that assesses familial risk for CHD; stroke; diabetes; and colorectal, breast, and ovarian cancer, and provides a personalized prevention plan based on familial risk. The Family Healthware Impact Trial evaluated the tool.

DESIGN

In this cluster RCT, participants completed baseline and 6-month follow-up surveys. The intervention group used Family Healthware directly after the baseline survey. Controls used the tool after completing the follow-up survey.

SETTING/PARTICIPANTS

Patients aged 35-65 years with no known diagnosis of these six diseases were enrolled from 41 primary care practices.

MAIN OUTCOME MEASURES

The prevalence of family-history-based risk for coronary heart disease (CHD); stroke; diabetes; and colorectal, breast, and ovarian cancer was determined in a primary care population.

RESULTS

From 2005 to 2007, 3786 participants enrolled. Data analysis was undertaken from September 2007 to March 2008. Participants had a mean age of 50.6 years and were primarily white (91%) women (70%). Of the 3585 participants who completed the risk assessment tool, 82% had a strong or moderate familial risk for at least one of the diseases: CHD (strong=33%, moderate=26%); stroke (strong=15%, moderate=34%); diabetes (strong=11%, moderate=26%); colorectal cancer (strong=3%, moderate=11%); breast cancer (strong=10%, moderate=12%); and ovarian cancer (strong=4%, moderate=6%). Women had a significantly (p<0.04) higher familial risk than men for all diseases except colorectal and ovarian cancer. Overweight participants were significantly (p<or=0.02) more likely to have a strong family history for CHD, stroke, and diabetes. Older participants were significantly (p<or=0.02) more likely to report a strong family history for CHD and stroke as well as colorectal and breast cancer.

CONCLUSIONS

This self-administered, online tool delineated a substantial burden of family-history-based risk for these chronic diseases in an adult, primary care population.

TRIAL REGISTRATION

NCT00164658.

Cancer diagnosis in first-degree relatives and non-small cell lung cancer risk: results from a multi-centre case-control study in Europe

Because aggregation of cancers at different sites can occur in families, cancer could be considered as a broad phenotype with shared genetic factors. Here, we report results from a multi-centre case-control study of non-small cell lung cancer (NSCLC), with particular emphasis on a history of cancer in first-degree relatives and the risk of lung cancer. From 2002 to 2006, 733 NSCLC patients treated surgically were recruited in 8 European countries and matched to 1312 controls, by centre, sex and age. We used multivariate conditional logistic regression models to test the association between a history of cancer in first-degree relatives and risk of NSCLC. A family history of lung cancer was associated with an odds ratio (OR) for early-onset (54 years or younger) NSCLC of 4.72 (95% confidence interval [CI]=1.02-21.90). A family history of gastric cancer was associated with an OR for NSCLC of 1.82 (95% CI=1.08-3.06) and for late-onset (55 years or older) NSCLC of 2.92 (95% CI=1.10-7.75). Our findings provide further evidence of a familial predisposition to lung cancer and support the hypothesis that family history is a significant risk factor for the disease. Because of the inherent potential for bias in familial case-control study design, cautious interpretation is warranted.

Family history of various cancers and pancreatic cancer mortality in a large cohort

A family history of pancreatic cancer is associated with increased risk of pancreatic cancer, but uncertainty remains about the magnitude of this association, whether it varies by age or smoking and whether a family history of other cancers may also be associated with increased risk. We examined family history of 14 cancers and pancreatic cancer mortality among ~1.1 million men and women in Cancer Prevention Study-II (CPS-II). CPS-II participants completed a questionnaire at enrollment in 1982. During follow-up through 2006, there were 7,306 pancreatic cancer deaths. A family history of pancreatic cancer in a parent or sibling was associated with pancreatic cancer mortality [multivariable adjusted rate ratio (RR) = 1.66, 95% confidence interval (CI) 1.43-1.94]. This association was stronger among participants aged under 60 (RR = 2.89, 95% CI 1.67-5.02) than among participants aged 60 or older (RR = 1.61, 95% CI 1.37-1.88). Weaker associations were observed for family history of stomach cancer (RR = 1.23, 95% CI 1.11-1.37), liver cancer (RR = 1.25, 95% CI 1.10-1.43), and colorectal cancer (RR = 1.12, 95% CI 1.01-1.23). Results from this large prospective study indicate family history of pancreatic cancer is associated with a moderate increase in risk of pancreatic cancer, and also identify associations with the family history of certain other cancers which may be useful in generating hypotheses about shared risk factors.

Screening for pancreatic cancer in high-risk individuals: a call for endoscopic ultrasound

Pancreatic cancer has a dismal prognosis, and early detection through screening is likely to be our best hope to improve survival. The relatively low incidence of pancreatic cancer and the insensitive screening techniques available currently render this approach prohibitively expensive and inefficient in the general population. Screening has begun, however, in the subset of patients at the highest risk of disease, such as those with inherited risk due to familial multiorgan cancer syndromes or in familial groupings of pancreatic cancer with yet unidentified genetic abnormalities, termed familial pancreatic cancer. Screening is currently done at several large centers in the world, each with a unique multidisciplinary approach and series of screening tests. Endoscopic ultrasound has emerged as the most promising imaging test given its high sensitivity and potential for tissue sampling. However, this potential to detect and cure early lesions should be carefully balanced with the risk of overtreatment, especially in view of the morbidity and mortality of pancreatic surgery. Additional experience to help determine the best screening strategy is greatly needed. Screening should therefore be done at experienced centers with multidisciplinary teams of specialists and in the context of research protocols.

Common variants on 9q22.33 and 14q13.3 predispose to thyroid cancer in European populations

In order to search for sequence variants conferring risk of thyroid cancer we conducted a genome-wide association study in 192 and 37,196 Icelandic cases and controls, respectively, followed by a replication study in individuals of European descent. Here we show that two common variants, located on 9q22.33 and 14q13.3, are associated with the disease. Overall, the strongest association signals were observed for rs965513 on 9q22.33 (OR = 1.75; P = 1.7 x 10(-27)) and rs944289 on 14q13.3 (OR = 1.37; P = 2.0 x 10(-9)). The gene nearest to the 9q22.33 locus is FOXE1 (TTF2) and NKX2-1 (TTF1) is among the genes located at the 14q13.3 locus. Both variants contribute to an increased risk of both papillary and follicular thyroid cancer. Approximately 3.7% of individuals are homozygous for both variants, and their estimated risk of thyroid cancer is 5.7-fold greater than that of noncarriers. In a study on a large sample set from the general population, both risk alleles are associated with low concentrations of thyroid stimulating hormone (TSH), and the 9q22.33 allele is associated with low concentration of thyroxin (T(4)) and high concentration of triiodothyronine (T(3)).

Impact of genetics on low bone mass in adults

Low bone mass in adults is a major risk factor for low-impact fractures and is considered of complex origin because of interaction of environmental and genetic factors, each with modest effect. The objective was to assess the relative impact of genetics and environment and quantify the risk in relatives of osteopenic individuals. We studied 440 Icelandic nuclear families with 869 first-degree relatives of both sexes. Index cases (male or female) had BMD in the lumbar spine or hip >1.5 SD less than sex-matched controls. Heritability of BMD was estimated by maximum likelihood method, and variance component analysis was used to partition the genetic and environmental effects. Relative risk of low BMD (< -1 SD) in first-degree relatives was estimated, and heritable decrement in BMD was calculated compared with controls. Heritability was estimated as 0.61-0.66. Relative risk among first-degree relatives was 2.28, and the yield of screening was as high as 36%. The genetic influence was consistent with one or a few genes with considerable effect in addition to multiple genes each with a small effect. The genetic deficit in BMD was already present before 35 yr of age and equaled bone loss during 8-30 yr after menopause. We confirmed that genetics are more important than environment to low bone mass in adults. Our results are consistent with a few underlying genes with considerable effect. The prevalence among first-degree relatives of both sexes is common, suggesting that screening them should be cost effective and informative to elucidate the underlying genetics.

Sequence variant on 8q24 confers susceptibility to urinary bladder cancer

We conducted a genome-wide SNP association study on 1,803 urinary bladder cancer (UBC) cases and 34,336 controls from Iceland and The Netherlands and follow up studies in seven additional case-control groups (2,165 cases and 3,800 controls). The strongest association was observed with allele T of rs9642880 on chromosome 8q24, 30 kb upstream of MYC (allele-specific odds ratio (OR) = 1.22; P = 9.34 x 10(-12)). Approximately 20% of individuals of European ancestry are homozygous for rs9642880[T], and their estimated risk of developing UBC is 1.49 times that of noncarriers. No association was observed between UBC and the four 8q24 variants previously associated with prostate, colorectal and breast cancers, nor did rs9642880 associate with any of these three cancers. A weaker signal, but nonetheless of genome-wide significance, was captured by rs710521[A] located near TP63 on chromosome 3q28 (allele-specific OR = 1.19; P = 1. 15 x 10(-7)).

Family history of cancer and stomach cancer risk

A family history of stomach cancer in first-degree relatives increases the risk of stomach cancer, but uncertainties remain as concerns the variation of the risk according to age, sex and type of relative, as well as on the role of family history of other cancers. We investigated the issue using data from a multicentric case-control study conducted in Italy between 1997 and 2007 on 230 cases aged not more than 80 years, with histologically confirmed incident gastric cancer and 547 controls admitted to hospital for acute, non neoplastic conditions. Logistic regression models adjusted for the effect of sex, age, year of interview, education, body mass index (BMI), tobacco smoking and number of brothers and sisters were used to estimate the odds ratios (OR) of stomach cancer. Relative to subjects with no history, those with a family history of gastric cancer had an OR of 2.5 (95% confidence interval (CI) 1.5-4.2). No significant heterogeneity emerged according to sex or age of the proband or of the affected relative, or smoking habits, BMI and education of the proband. As suggested from previous studies the OR was higher when the affected relative was a sibling (OR=5.1, 95% CI: 1.3-20.6) rather than a parent (OR=2.2, 95% CI: 1.2-3.9), although the heterogeneity test was not significant. The risk of stomach cancer was not increased in subjects with a family history of cancer at any other site. The OR for all sites excluding stomach was 1.0 (95% CI: 0.7-1.4).

Cancer risks among relatives of children with Hodgkin and non-Hodgkin lymphoma

A role for genetic susceptibility in the aetiology of childhood lymphomas was investigated in 454 families of children with histologically confirmed Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) from Northwest England. Cancers in parents were obtained from the UK National Health Service Central Register and in other close relatives by interview with the parents. The cancer incidence among relatives was compared with expected incidence based on cancer registry data for England. There were 197 cancers in relatives (SIR 1.0 95% CI 0.8-1.1). In families of children with HL, there was an excess of HL in the first degree relatives (SIR 5.8 95% CI 1.2-16.9). Excesses of HL diagnosed under population median age (SIR 4.1 95% CI 1.1-10.6) were seen among all relatives and relatives of children who were below the median age at diagnosis (SIR 5.5 95% CI 1.1-16.0). In families of children with NHL, there were non-significant excesses of central nervous system (CNS) tumours in the first degree relatives (SIR 2.9 95% CI 0.8-7.4) and in the second and third degree relatives (SIR 1.5). There were significant excesses of CNS tumours diagnosed under the population median age (SIR 2.8 95% CI 1.1-5.8) in all relatives. Excess CNS tumours were also seen among relatives of children below the median age at diagnosis (SIR 3.2 95% CI 1.1-7.6). In conclusion, genetic susceptibility in some families of children with lymphoma might be operating, but aetiologies in HL and NHL appear to be different. Possible interpretations of our findings, in the context of putative genetic and infectious aetiologies, are discussed.

Exchangeable models of complex inherited diseases

A model of unlinked diallelic loci affecting the risk of a complex inherited disease is explored. The loci are equivalent in their effect on disease risk and are in Hardy-Weinberg and linkage equilibrium. The goal is to determine what assumptions about dependence of disease risk on genotype are consistent with data for diseases such as schizophrenia, bipolar disorder, autism, and multiple sclerosis that are relatively common (0.1-2% prevalence) and that have high concordance rates for monozygotic twins (30-50%) and high risks to first-degree relatives of affected individuals (risk ratios exceeding 4). These observations are consistent with a variety of models, including generalized additive, multiplicative, and threshold models, provided that disease risk increases rapidly for a narrow range of numbers of causative alleles. If causative alleles are in relatively high frequency, then the combined effects of numerous causative loci are necessary to substantially elevate disease risk.

[Early pancreatic cancer: can the methods currently available identify this disease?]

OBJECTIVES

Call attention of the gastroenterologists and surgeons on the patients with high risk of developing pancreatic carcinoma, and whether or not forms of surveillance and prevention of this disease, which can be applied to daily clinical practice. DATA SURVEY: It was used the database of PubMed (US National Library of Medicine), looked up the publications of recent years for the groups at risk, molecular biological testing and methods of image used in the identification of small tumors of the pancreas.

BACKGROUND

The survival rates of adenocarcinoma of the pancreas remain negligible, even after the significant advances in diagnosis by imaging, treatment and understanding of the molecular biology of this disease. Although embryonic strategies for surveillance and prevention for people with high risk of pancreatic cancer has developed.

CONCLUSIONS

This review summarizes how to identify people at high risk of developing this disease and what is the state of the art of genetic counseling and screening through techniques of image available.

Screening and surveillance approaches in familial pancreatic cancer

Screening and surveillance for pancreatic cancer and its precursors is a relatively new indication for endoscopic ultrasound. It provides an alternative approach to the ineffective treatment of mostly incurable symptomatic pancreatic cancer. It is currently reserved for individuals with an increased risk for pancreatic ductal adenocarcinoma, such as those who have inherited genetic syndromes (eg, patients who have Peutz-Jeghers syndrome or hereditary pancreatitis, germline mutation carriers of p16 and BRCA2) and at-risk relatives of patients who have familial pancreatic cancer. This article discusses the rationale for performing screening and surveillance, the types of patients who are eligible for screening, the diagnostic modalities and technique for screening, the diagnostic yield of screening, and the ongoing research.

Polygenes, risk prediction, and targeted prevention of breast cancer

BACKGROUND

New developments in the search for susceptibility alleles in complex disorders provide support for the possibility of a polygenic approach to the prevention and treatment of common diseases.

METHODS

We examined the implications, both for individualized disease prevention and for public health policy, of findings concerning the risk of breast cancer that are based on common genetic variation.

RESULTS

Our analysis suggests that the risk profile generated by the known, common, moderate-risk alleles does not provide sufficient discrimination to warrant individualized prevention. However, useful risk stratification may be possible in the context of programs for disease prevention in the general population.

CONCLUSIONS

The clinical use of single, common, low-penetrance genes is limited, but a few susceptibility alleles may distinguish women who are at high risk for breast cancer from those who are at low risk, particularly in the context of population screening.

Lung cancer epigenetics and genetics

Lung cancer is the leading cause of cancer-related death and thus a major health problem. The efficiency of current treatment modalities for lung cancer depends strongly on the time of diagnosis, with better chances of survival if a tumor has been detected at an early stage. Thus, there is an urgent need for rapid and efficient early detection methods. Biomarkers represent a possible alternative to current, rather expensive, screening tools such as spiral computer tomography (CT), or may allow the identification of high risk groups for whom screening would be cost efficient. Although most lung cancers are the consequence of smoking, a substantial fraction of molecular-epidemiological studies point to high-prevalence, low-penetrance genetic polymorphisms as modifiers of environmental lung cancer risk. In the past the genomics field has also made significant advances in identifying genetic lesions that can now be harvested with the goal of identifying novel biomarkers for lung cancer. Furthermore, the importance of epigenetic changes that occur during lung cancer development has been reported, but has been underestimated in the past. Novel high-throughput, quantitative assays for the detection of DNA methylation or histone tail modifications are now applied, to search for alterations in the lung cancer genome and will identify novel cancer-related genes that may become attractive targets for treatment, provide new insight into the biology of lung cancers, and could also become useful biomarkers for the early detection of lung cancer in sputum, or may be used as prognostic markers. Thus, an integrative approach in lung cancer research combining epidemiological, genetic and epigenetic information becomes an important concept for the future.

Pancreatic cancer

The past two decades have witnessed an explosion in our understanding of pancreatic cancer, and it is now clear that pancreatic cancer is a disease of inherited (germ-line) and somatic gene mutations. The genes mutated in pancreatic cancer include KRAS2, p16/CDKN2A, TP53, and SMAD4/DPC4, and these are accompanied by a substantial compendium of genomic and transcriptomic alterations that facilitate cell cycle deregulation, cell survival, invasion, and metastases. Pancreatic cancers do not arise de novo, and three distinct precursor lesions have been identified. Experimental models of pancreatic cancer have been developed in genetically engineered mice, which recapitulate the multistep progression of the cognate human disease. Although the putative cell of origin for pancreatic cancer remains elusive, minor populations of cells with stem-like properties have been identified that appear responsible for tumor initiation, metastases, and resistance of pancreatic cancer to conventional therapies.

Pancreatic carcinogenesis

Pancreatic cancer is an almost universally lethal disease. Research over the last two decades has shown that pancreatic cancer is fundamentally a genetic disease, caused by inherited germline and acquired somatic mutations in cancer-associated genes. Multiple alterations in genes that are important in pancreatic cancer progression have been identified, including tumor suppressor genes, oncogenes, and genome maintenance genes. Furthermore, the identification of noninvasive precursor lesions of pancreatic adenocarcinoma has led to the formulation of a multi-step progression model of pancreatic cancer and the subsequent identification of early and late genetic alterations culminating in invasive cancer. In addition, an increased understanding of the molecular basis of the disease has facilitated the identification of new drug targets enabling rational drug design. The elucidation of genetic alterations in combination with the development of high-throughput sensitive techniques should lead to the discovery of effective biomarkers for early detection of this malignancy. This review focuses mainly on the current knowledge about the molecular insights of the pathogenesis of pancreatic ductal adenocarcinoma.

Inherited predisposition of lung cancer: a hierarchical modeling approach to DNA repair and cell cycle control pathways

The DNA repair systems maintain the integrity of the human genome and cell cycle checkpoints are a critical component of the cellular response to DNA damage. We hypothesized that genetic variants in DNA repair and cell cycle control pathways will influence the predisposition to lung cancer, and studied 27 variants in 17 DNA repair enzymes and 10 variants in eight cell cycle control genes in 1,604 lung cancer patients and 2,053 controls. To improve the estimation of risks for specific variants, we applied a Bayesian approach in which we allowed the prior knowledge regarding the evolutionary biology and physicochemical properties of the variant to be incorporated into the hierarchical model. Based on the estimation from the hierarchical modeling, subjects who carried OGG1 326C/326C homozygotes, MGMT 143V or 178R, and CHEK2 157I had an odds ratio of lung cancer equal to 1.45 [95% confidence interval (95% CI), 1.05-2.00], 1.18 (95% CI, 1.01-1.40), and 1.58 (95% CI, 1.14-2.17). The association of CHEK2 157I seems to be overestimated in the conventional analysis. Nevertheless, this association seems to be robust in the hierarchical modeling. None of the pathways seem to have a prominent effect. In general, our study supports the notion that sequence variation may explain at least some of the variation of inherited susceptibility. In particular, further investigation of OGG1, MGMT, and CHEK2 focusing on the genetic regions where the present markers are located or the haplotype blocks tightly linked with these markers might be warranted.

Possible imprinting and microchimerism in chronic lymphocytic leukemia and related lymphoproliferative disorders

Based on the concept that the tumorogenesis in chronic lymphocytic leukaemia comprises both an initial, inherited mutation and subsequent somatic mutations, the pleiotypic diversity of familial chronic lymphocytic leukaemia and related malignant lymphoproliferative disorders is generally explained by a repertoire of monoallelic polygenes in the initial mutation. Epigenetic genomic imprinting is a likely mechanism behind of the asynchroneous replicating monoallelic polygenes which is discussed in the light of pleiotrophy and birth order effect. Furthermore, it is discussed that one possible mechanism available for the epigenetic transfer of these genes could be the physiological pregnancy-related microchimerism between mother and fetus.

Lessons from the past: familial aggregation analysis of fatal pandemic influenza (Spanish flu) in Iceland in 1918

The pandemic influenza of 1918 (Spanish flu) killed 21-50 million people globally, including in Iceland, where the characteristics and spread of the epidemic were well documented. It has been postulated that genetic host factors may have contributed to this high mortality. We identified 455 individuals who died of the Spanish flu in Iceland during a 6-week period during the winter of 1918, representing >92% of all fatal domestic cases mentioned by historical accounts. The highest case fatality proportion was 2.8%, and peak excess mortality was 162/100,000/week. Fatality proportions were highest among infants, young adults, and the elderly. A genealogical database was used to study relatedness and relative risk (RR) of the fatal influenza victims and relatives of their unaffected mates. The significance of these RR computations was assessed by drawing samples randomly from the genealogical database matched for age, sex, and geographical distribution. Familial aggregation of fatalities was seen, with RRs for death ranging from 3.75 for first-degree relatives (P < 0.0001) to 1.82 (P = 0.005), 1.12 (P = 0.252), and 1.47 (P = 0.0001) for second- to fourth-degree relatives of fatal influenza victims, respectively. The RRs within the families of unaffected mates of fatal influenza victims were 2.95 (P < 0.0001), 1.27 (P = 0.267), 1.35 (P = 0.04), and 1.42 (P = 0.001), for first- to fourth-degree relatives, respectively. In conclusion, the risk of death from the Spanish flu was similar within families of patients who succumbed to the illness and within families of their mates who survived. Our data do not provide conclusive evidence for the role of genetic factors in susceptibility to the Spanish flu.

Familial risks for common diseases: etiologic clues and guidance to gene identification

Familial clustering of a disease is a direct indicator of a possible heritable cause, provided that environmental sharing can be excluded. If the familial clustering is lacking, the likelihood of a heritable influence is also small. In the era of genome scans, the consideration of data on heritability should be important in the assessment of the likely success of the genome scan. The availability of a Multigeneration Register in Sweden provides a reliable access to families throughout the last century. This Register has been extensively used to study a number of different diseases through linkage to the Hospital Discharge Register. In the present article we review the obtained and some unpublished results for nine main disease classes. For each of these, familial risks are given for four disease subtypes. As measures of familial clustering we use risks between siblings, twins and spouses. Disease correlation between spouses suggests environmental sharing and a higher correlation between siblings and particularly twins shows heritable effects. We will also comment on the established susceptibility genes and the risks conferred by them. The data suggest high heritabilities for chronic obstructive pulmonary disease, asthma, noninfective enteritis and colitis, cerebral palsy and endocrine and metabolic diseases. Among the performed first-generation genome scans on various diseases, the success appears to be related to the a priori heritability estimates. To our knowledge this is a first attempt to summarize familial risks for a large number of diseases using data from a single population on which reasonable uniform diagnostic criteria have been applied.

CDKN2A mutations and melanoma risk in the Icelandic population

BACKGROUND

Germline CDKN2A mutations have been observed in 20-40% of high risk, melanoma prone families; however, little is known about their prevalence in population based series of melanoma cases and controls.

METHODS

We resequenced the CDKN2A gene, including the p14ARF variant and promoter regions, in approximately 703 registry ascertained melanoma cases and 691 population based controls from Iceland, a country in which the incidence of melanoma has increased rapidly.

RESULTS

We identified a novel germline variant, G89D, that was strongly associated with increased melanoma risk and appeared to be an Icelandic founder mutation. The G89D variant was present in about 2% of Icelandic invasive cutaneous malignant melanoma cases. Relatives of affected G89D carriers were at significantly increased risk of melanoma, head and neck cancers, and pancreatic carcinoma compared to relatives of other melanoma patients. Nineteen other germline variants were identified, but none conferred an unequivocal risk of melanoma.

CONCLUSIONS

This population based study of Icelandic melanoma cases and controls showed a frequency of disease related CDKN2A mutant alleles ranging from 0.7% to 1.0%, thus expanding our knowledge about the frequency of CDKN2A mutations in different populations. In contrast to North America and Australia where a broad spectrum of mutations was observed at a similar frequency, in Iceland, functional CDKN2A mutations consist of only one or two different variants. Additional genetic and/or environmental factors are likely critical for explaining the high incidence rates for melanoma in Iceland. This study adds to the geographic regions for which population based estimates of CDKN2A mutation frequencies are available.

How common is familial cancer?

BACKGROUND

Family history of a disease may point to its heritable or environmental etiology. It can be described by the proportion of the familial disease, i.e. same disease in two or more family members. A family history always needs to be specified as to the number of generations covered and their ages.

PATIENTS AND METHODS

Proportions of site-specific familial cancers (familial proportions) were calculated using the Swedish Family-Cancer Database, the largest dataset of its kind in the world, with cancers from the Swedish Cancer Registry. Familial proportions refer to the offspring population up to age 72 years when their parents or siblings were diagnosed with a concordant (same) cancer.

RESULTS

A total of 34 cancer sites and 205 638 cases were covered. Prostate cancer showed the highest familial proportion of 20.15%, followed by breast (13.58%) and colorectal (12.80%) cancers. Salivary gland cancers showed the lowest familial proportion of 0.15%, but bone, laryngeal, anal, connective tissue and other genital cancers also remained <1%. The familial proportion depended on the prevalence of the particular cancer and on its familial risk.

CONCLUSIONS

The derived familial proportions can justifiably be used in statements 'X% of the patients had a family history of the cancer'.

Precursors to pancreatic cancer

Infiltrating ductal adenocarcinoma of the pancreas is believed to arise from morphologically distinct noninvasive precursor lesions. These precursors include the intraductal papillary mucinous neoplasm, the mucinous cystic neoplasm, and pancreatic intraepithelial neoplasia. Intraductal papillary mucinous neoplasms are grossly visible mucin-producing epithelial neoplasms that arise in the main pancreatic duct or one of its branches. The cysts of mucinous cystic neoplasms do not communicate with the major pancreatic ducts, and these neoplasms are characterized by a distinct ovarian-type stroma. Pancreatic intraepithelial neoplasia is a microscopic lesion. This article focuses on the clinical significance of these three important precursor lesions, with emphasis on their clinical manifestations, detection, and treatment.

Molecular profiling of chronic lymphocytic leukaemia: genetics meets epigenetics to identify predisposing genes

Molecular profiling may lead to a better understanding of a disease. This knowledge is especially important in malignancies, where multiple alterations are required during the progression from premalignant to malignant stages. Such information can be useful for the development of novel biomarkers that allow the prediction of a clinical course, response to treatment or early detection. Molecular data is also utilized to develop targeted therapies. Moreover, gene defects identified in profiling studies will help to understand the molecular pathways disrupted in the disease. This review provides an overview of molecular profiling approaches in chronic lymphocytic leukaemia (CLL). We will describe our current understanding of genetic alterations in CLL, the use of familial CLL for the identification of predisposing mutations, and the search for epigenetic alterations in CLL.

Family history and the risk of kidney cancer: a multicenter case-control study in Central Europe

An elevated familial relative risk may indicate either an important genetic component in etiology or shared environmental exposures within the family. Incidence rates of kidney cancer are particularly high in Central Europe, although no data were available on the familial aggregation or genetic background of kidney cancer in this region. We have, therefore, investigated the role of family history in first-degree relatives in a large multicenter case-control study in Central Europe. A total number of 1,097 cases of kidney cancer and 1,555 controls were recruited from 2000 to 2003 from seven centers in Czech Republic, Poland, Romania, and Russia. The risk of kidney cancer increased with the increasing number of relatives with history of any cancer [odds ratio (OR), 1.15; 95% confidence interval (95% CI), 1.00-1.31 per affected relative], and this association seemed to be more prominent among subjects with young onset (OR, 1.55; 95% CI, 1.09-2.20 per affected relative). Overall, the OR was 1.40 (95% CI, 0.71- 2.76) for the subjects who had at least one first-degree relative with kidney cancer after adjusting for tobacco smoking, body mass index, and medical history of hypertension, and this association was most apparent among subjects with affected siblings (OR, 4.09; 95% CI, 1.09-15.4). Based on the relative risk to siblings in our study population, we estimated that 80% of the kidney cancer cases are likely to occur in 20% of the population with the highest genetic risk, which indicate the importance of further investigation of genetic factors in cancer prevention for kidney cancer.

Familial pancreatic cancer: from genes to improved patient care

Pancreatic cancer is essentially a disease caused by inherited and acquired mutations in cancer-causing genes. A number of the genes responsible for the aggregation of pancreatic cancer in families have been discovered, including BRCA2, p16/CDKN2A, STK11 and PRSS1. Individuals can be tested for germline mutations in these genes; however, until recently, little could be done about the risk of pancreatic cancer if a patient was found to carry a mutation. Currently, new approaches are being developed to screen at-risk individuals for curable precancerous pancreatic lesions and laboratory studies have led to novel therapies that specifically target some of these genetic defects. This review focuses on the genetic basis for the familial aggregation of pancreatic cancer, with emphasis placed on the implications of the genetic alterations on clinical patient care.

Advances in counselling and surveillance of patients at risk for pancreatic cancer

Even with significant advances in imaging and our understanding of pancreatic cancer genetics, the survival rates for pancreatic cancer remain quite dismal. Although still at an early stage, there are efforts in place to develop surveillance and prevention strategies for people at high risk for pancreatic cancer. This comprehensive review article summarises the predispositions that put people at a high risk of developing pancreatic cancer and the current status in the counselling and surveillance of these people using not only available medical literature, but also incorporating international expert opinion.

A common genetic background for inflammatory bowel disease and ankylosing spondylitis: a genealogic study in Iceland

OBJECTIVE

Patients with ankylosing spondylitis (AS) and approximately 50% of their first-degree relatives may have a genetic abnormality that results in subclinical intestinal inflammation. This study was undertaken to examine the familial occurrence and cosegregation of AS and inflammatory bowel disease (IBD) in order to determine whether there is a shared genetic risk factor in families.

METHODS

The Icelandic genealogy database and population-wide data on all living Icelanders diagnosed as having AS (n = 205) and/or IBD (n = 1,352) were used to estimate the risk ratios of AS for relatives of patients with AS, the risk ratios of IBD for relatives of patients with IBD, and the cross-risk ratios of AS for relatives of patients with IBD or of IBD for relatives of patients with AS. The mean kinship coefficients for each disease were calculated. The control population for disease risk calculations comprised 10,000-100,000 sets of matched Icelandic subjects.

RESULTS

First-, second-, and third-degree relatives of patients with AS had risk ratios of 94, 25, and 3.5, respectively, indicating an increased risk of developing AS (each P < 0.0005), while first-, second-, and third-degree relatives of patients with IBD had risk ratios for IBD of 4.4, 2.2, and 1.4, respectively (each P < 0.0001). The cross-risk ratios of IBD were 3.0 and 2.1 in first- and second-degree relatives of patients with AS, respectively, and were the same for AS in first- and second-degree relatives of patients with IBD. With the exception of Crohn's disease, the risk of having AS, ulcerative colitis, or IBD in spouses of patients with these diseases did not differ significantly from that in controls. Calculation of the kinship coefficients confirmed these patterns of familial risk.

CONCLUSION

Patients with AS or IBD in Iceland are significantly more related to each other than are randomly sampled control subjects, in terms of an increased risk of either or both conditions developing in third-degree relatives. These findings suggest that one or more undiscovered genetic variants may underlie the risk of both diseases.

Genetic susceptibility for breast cancer: How many more genes to be found?

Today, breast cancer is the most commonly occurring cancer among women. It accounts for 22% of all female cancers and the estimated annual incidence of breast cancer worldwide is about one million cases. Many risk factors have been identified but a positive family history remains among the most important ones established for breast cancer, with first-degree relatives of patients having an approximately two-fold elevated risk. It is currently estimated that approximately 20-25% of this risk is explained by known breast cancer susceptibility genes, mostly those conferring high risks, such as BRCA1 and BRCA2. However, these genes explain less than 5% of the total breast cancer incidence, even though several studies have suggested that the proportion of breast cancer that can be attributed to a genetic factor may be as high as 30%. It is thus likely that there are still breast cancer susceptibility genes to be found. It is presently not known how many such genes there still are, nor how many will fall into the class of rare high-risk (e.g. BRCAx) or of common low-risk susceptibility genes, nor if and how these factors interact with each other to cause susceptibility (a polygenic model). In this review we will address this question and discuss the different undertaken approaches used in identifying new breast cancer susceptibility genes, such as (genome-wide) linkage analysis, CGH, LOH, association studies and global gene expression analysis.

Downregulation of death-associated protein kinase 1 (DAPK1) in chronic lymphocytic leukemia

The heritability of B cell chronic lymphocytic leukemia (CLL) is relatively high; however, no predisposing mutation has been convincingly identified. We show that loss or reduced expression of death-associated protein kinase 1 (DAPK1) underlies cases of heritable predisposition to CLL and the majority of sporadic CLL. Epigenetic silencing of DAPK1 by promoter methylation occurs in almost all sporadic CLL cases. Furthermore, we defined a disease haplotype, which segregates with the CLL phenotype in a large family. DAPK1 expression of the CLL allele is downregulated by 75% in germline cells due to increased HOXB7 binding. In the blood cells from affected family members, promoter methylation results in additional loss of DAPK1 expression. Thus, reduced expression of DAPK1 can result from germline predisposition, as well as epigenetic or somatic events causing or contributing to the CLL phenotype.

Family history of cancer in children with acute leukemia, Hodgkin's lymphoma or non-Hodgkin's lymphoma: the ESCALE study (SFCE)

The role of a family history of cancer in the etiology of childhood hematopoietic malignancies was investigated using the data from the ESCALE study. ESCALE, a population-based case-control study, was carried out in France over the period, 2003-2004. A total of 773 cases of acute leukemia (AL), 130 of Hodgkin's lymphoma (HL), 163 of non-Hodgkin's lymphoma (NHL) and 1,681 population-based controls were included. The controls were randomly selected from the French population and were frequency matched with the cases on age and gender. Cancer history in first- and second-degree relatives was reported by the mothers in a structured telephone questionnaire that was the same for the cases and controls. Odds ratios (ORs) were estimated using an unconditional regression model taking into account the stratification variables and potential confounders. A family history of cancer was associated with an increased risk of HL (OR = 1.5 [1.0-2.2]) and NHL (OR = 1.8 [1.3-2.5]), but not AL (OR = 1.0 [0.9-1.2]). The ORs were higher when at least 2 relatives had a history of cancer or when 1 case occurred before age 46 years. Only HL was significantly associated with a family history of hematopoietic malignancies (OR = 2.0 [1.0-3.8]), mainly because of a significant association with a history of HL (OR = 5.4 [1.3-22]). In conclusion, the study findings support the hypothesis of familial susceptibility to childhood lymphoma, but do not suggest familial susceptibility to childhood AL.

Common variants on chromosomes 2q35 and 16q12 confer susceptibility to estrogen receptor-positive breast cancer

Familial clustering studies indicate that breast cancer risk has a substantial genetic component. To identify new breast cancer risk variants, we genotyped approximately 300,000 SNPs in 1,600 Icelandic individuals with breast cancer and 11,563 controls using the Illumina Hap300 platform. We then tested selected SNPs in five replication sample sets. Overall, we studied 4,554 affected individuals and 17,577 controls. Two SNPs consistently associated with breast cancer: approximately 25% of individuals of European descent are homozygous for allele A of rs13387042 on chromosome 2q35 and have an estimated 1.44-fold greater risk than noncarriers, and for allele T of rs3803662 on 16q12, about 7% are homozygous and have a 1.64-fold greater risk. Risk from both alleles was confined to estrogen receptor-positive tumors. At present, no genes have been identified in the linkage disequilibrium block containing rs13387042. rs3803662 is near the 5' end of TNRC9 , a high mobility group chromatin-associated protein whose expression is implicated in breast cancer metastasis to bone.

The epidemiology of bladder and kidney cancer

Bladder and kidney cancer together account for about 5% of cancers worldwide, and represent the 9th and 14th most common cancers in terms of absolute numbers, respectively. Our knowledge of these two cancers, however, indicates that they have strikingly different etiology. A number of important occupational, lifestyle and genetic factors have been implicated in bladder carcinogenesis, which have greatly increased our understanding of this disease. In some instances, identification of these factors has contributed to the prevention or reduction of exposure to bladder carcinogens. Conversely, the etiology of kidney cancer is less well elucidated, which limits the possibilities for reducing its incidence by this approach. It is likely that much remains to be uncovered about the causes of these two cancers, and these advances will increase our appreciation of the biology of these cancers and perhaps lead to further possibilities for their prevention. In this article, we evaluate the epidemiology of bladder and kidney cancer and also discuss potential priorities for future research.

Estimates of heritable and environmental components of familial breast cancer using family history information

Using the Swedish Family-Cancer Database, the increased risk of breast cancer in women with relatives with the disease did not vary with paternal/maternal lineage. Familial breast cancer heritable component was 73% and the environmental proportion 27%. Familial aggregation of breast cancer in women below age 51 years is mainly due to heritable causes.

Familial risk for gastric carcinoma: an updated study from Sweden

Reliable data on familial risks are important for clinical counselling and cancer genetics. However, the estimates of familial risk of gastric cancer vary widely. We examined the risk of familial gastric cancer using the updated Swedish Family-Cancer Database with 5358 patients among offspring and 36 486 patients among parents. There were 133 families with one parent and one offspring diagnosed with gastric cancer, and 20 families with two affected offspring. Familial standardised incidence ratios (SIRs) were 1.63 and 2.93 when parents and siblings presented with gastric cancer, respectively. The high sibling risk was owing to cancer in the corpus (SIR 7.28). The SIR for cardia cancer was 1.54 when parents were diagnosed with any gastric cancer. Cardia cancer associated with oesophageal cancer, particularly with oesophageal adenocarcinoma. Among specific histologies, signet ring cancer showed an increase. A few associations were noted for discordant sites, including the urinary bladder and the endometrium. H. pylori infection, although not measured in the present study, is probably an important risk factor for the high sibling risk of corpus cancer. Familial clustering of cardia cancer is independent of H. pylori infection, and may have a genetic basis. The familial association of cardia cancer with oesophageal adenocarcinoma may provide aetiological clues.

The balance between heritable and environmental aetiology of human disease

The Human Genome Project and the ensuing International HapMap Project were largely motivated by human health issues. But the distance from a DNA sequence variation to a novel disease gene is considerable; for complex diseases, closing this gap hinges on the premise that they arise mainly from heritable causes. Using cancer as an example of complex disease, we examine the scientific evidence for the hypothesis that human diseases result from interactions between genetic variants and the environment.

The updated Swedish family-cancer database used to assess familial risks of prostate cancer during rapidly increasing incidence

The Swedish Family-Cancer Database has been used for some 10 years in the study of familial risks at all common sites. In the present paper we describe some of the main features of version VII of this Database, assembled in year 2006. This update included all residents in Sweden born or immigrated in 1932 and later (offspring) with their biological parents, a total of 11.5 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry from years 1958 to 2004, including over 1.2 million first and multiple primary cancers and in situ tumours. We show one application of the Database in the study of familial risks in prostate cancer, with special reference to the modification of familial risk at the time of about 50% increase in incidence due to prostate specific antigen (PSA) screening. The familial risks for prostate cancer were 1.92 for sons of affected fathers, 3.03 for brothers and 5.44 for men with an affected father and an affected brother. Familial risk for prostate cancer according to the time since the first family member was diagnosed showed significant increases for two family members being diagnosed in the same year compared to 5+ years apart. Increased surveillance and the availability of PSA screening are the likely reasons for the overestimated familial relative risk shortly after the first diagnosis. This lead time bias should be considered in clinical counselling.

Pancreatic cancer genetic epidemiology consortium

We have organized the Pancreatic Cancer Genetic Epidemiology (PACGENE) Consortium to identify susceptibility genes in familial pancreatic cancer (FPC). The Consortium comprises seven data collection centers, a statistical genetics core, and a pathology/archival genotyping core. We recruit kindreds containing two or more affected blood relatives ascertained through incident pancreatic adenocarcinoma cases, physician referrals, and/or through Internet recruitment. Accrual to a database containing core clinical, demographic, lifestyle, and family history information from questionnaires is ongoing, along with biospecimen collection. To date, 13,147 patients have been screened for family history, of whom 476 (50% male) probands and 1,912 of their adult (99% unaffected) relatives have been enrolled. Of these, 379 kindreds meet criteria for FPC, having at least two first-degree relatives with pancreatic cancer. Cumulative incidence curves using available age of diagnosis (onset) among and affected relatives were compared with those for incident pancreatic cancer cases reported to 13 U.S. Surveillance Epidemiology and End Results (SEER) sites from 1973 to 2000 (N = 72,700). The mean age +/- SD at diagnosis among 466 PACGENE probands and 670 affected relatives was 64.1 +/- 11.8 and was 65.4 +/- 11.6 for the subset of 369 FPC probands and 429 relatives. Both samples were significantly younger than the mean age at diagnosis in the SEER population (70.0 +/- 12.1 years; differences in curves versus SEER, P < 0.001). Age at diagnosis (excluding probands) in FPC kindreds does not decrease with increasing number of affected individuals. In our sample, younger age at diagnosis was observed whether we grouped probands by recruitment sites that predominantly recruited through high-risk referrals, or through screening all pancreatic cancer patients for family history. Linkage studies are ongoing. The PACGENE Consortium will be a valuable family-based resource that will greatly enhance genetic epidemiology research in pancreatic cancer.

A family history of pancreatic cancer

BACKGROUND

A 65-year-old white male with a family history of pancreatic cancer and a personal history of two episodes of acute pancreatitis was referred to our department in January 2005 by his primary-care physician for an assessment of his pancreatic cancer risk.

INVESTIGATIONS

Physical exam, laboratory investigations, CT scan, endoscopic ultrasonography, endoscopic retrograde cholangiopancreatography.

DIAGNOSIS

Familial pancreatic cancer.

MANAGEMENT

Subtotal pancreatectomy, referral to genetic counselor, and continued surveillance.

Gene-Environment Interactions in Cancer: Do They Exist?

Single nucleotide polymorphisms (SNPs) are extensively used in case-control studies of practically all cancer types. In addition to the pure genetic studies, gene-environment studies, which simultaneously consider environmental factors, have been increasingly conducted. All SNP studies aim at the identification of the role of inherited cancer susceptibility genes. However, being genetic markers, they are applicable only on heritable conditions, which is often a neglected fact. Based on the data on the heritability of cancer and the importance of environmental factors in cancer etiology, we discuss the likelihood of successful gene-environment studies. The available evidence is not conclusive, but it consistently points to a minor heritable etiology in cancer, which will hamper the success of SNP-based association studies. We use simulation techniques to examine which situations would favor the application of a gene-environment approach instead of the traditional environmental approach in case-control studies. The results show that well-chosen candidate gene with a relatively low allele frequency may improve the power to detect environmental determinants of a disease. However, this advantage is lost when the number of underlying genes increases. We are concerned about an indiscriminate use of genetic tools for cancers, which are mainly environmental in origin. The likelihood of success for SNP-based gene-environment studies increases if established environmental risk factors are tested on proven candidate genes. Enhancing the likelihood that the disease causation is genetic, for example, by selecting familial cases, may increase the power of the studies, and the rareness of those cases calls for collaborative networks.

Multifocal neoplastic precursor lesions associated with lobular atrophy of the pancreas in patients having a strong family history of pancreatic cancer

We screened 116 patients with a strong family history of pancreatic cancer using a combination of endoscopic ultrasound and computed tomography. Ten of these patients underwent surgical resection at our institution, providing an opportunity to define the morphology of pancreatic precursor lesions in patients with a strong family history of pancreatic cancer. Eight of the 10 pancreata were available and these were entirely submitted for histologic examination. The number of pancreatic intraepithelial neoplasia (PanIN) lesions and intraductal papillary mucinous neoplasms (IPMNs) were compared with age-matched controls. Parenchymal changes were defined. Selected precursor neoplasms from 6 pancreata were microdissected and analyzed for KRAS gene mutations. PanINs were significantly more common in the 8 cases (mean of 10.7% of the duct profiles, range 1.0% to 27.3%) than in the controls (mean 1.9%, range 0% to 9.2%, P<0.01). Different KRAS gene mutations were identified in separately microdissected precursor lesions in 2 of 6 cases. IPMNs were identified in 4 of the 8 cases, including 2 pancreata each having 2 distinct IPMNs. Both the IPMNs and the PanINs, even the low-grade PanIN-1 lesions, were associated with lobular parenchymal atrophy. Some individuals with a strong family history of pancreatic cancer develop multifocal, noninvasive epithelial precursor lesions of the pancreas. PanINs and IPMNs produce obstructive lobular atrophy, and this atrophy is likely the source of the chronic pancreatitis-like changes seen in these patients. The multifocal nature of familial pancreatic neoplasia suggests that surveillance of these patients is warranted after partial pancreatectomy.