Systematic population-based assessment of cancer risk in first-degree relatives of cancer probands

Interaction between CHEK2*1100delC and other low-penetrance breast-cancer susceptibility genes: a familial study

BACKGROUND

The allele CHEK2*1100delC doubles the risk of breast cancer in unselected women, but could confer a greater risk in women with a family history of the disease, particularly of bilateral breast cancer. Our aim was to measure the risk of breast cancer in relatives of women with bilateral breast cancer who were carriers of this allele.

METHODS

A population-based series of 469 bilateral breast cancer cases ascertained through English cancer registries were genotyped for CHEK2*1100delC. Standardised incidence ratios (SIRs) and cumulative risks were calculated for breast cancer, prostate cancer, and all other cancers in the first-degree relatives of carriers and non-carriers.

FINDINGS

The relatives of bilateral cases who were wild-type for CHEK2 had three times the population risk of female breast cancer (145 cases: SIR 3.48 (95% CI 2.96-4.09), twice the risk of prostate cancer (34 cases: SIR 2.41, 1.67-3.36) and a large excess of male breast cancer (five cases: SIR 15.06, 4.92-35.36). Relatives of those who were carriers of CHEK2*1100delC had a substantially higher risk of breast cancer (eight cases: SIR 12.11, 5.23-23.88) and possibly prostate cancer (two cases: SIR 9.87, 1.20-35.67).

INTERPRETATION

These data suggest a multiplicative interaction between CHEK2*1100delC and other unknown susceptibility genes. In women with a family history of bilateral disease, CHEK2*1100delC confers a high lifetime risk and might be useful for predictive testing. Bilateral breast cancer cases and their families are likely to provide an efficient basis for identification of additional low-penetrance breast-cancer genes.

Familial papillary thyroid carcinoma

Over the last decade, several lines of evidence have been accumulated that support the existence of fPTC susceptibility genes. Preliminary clinical characteristics of fPTC have been identified, and linkage studies have identified the chromosomal locations of putative fPTC susceptibility genes. A logical clinical approach to fPTC is emerging.

Population-based family studies in genetic epidemiology

Designs that involve families (the traditional strength of genetic epidemiology) and population-based sampling (the traditional strength of environmental epidemiology) allow investigation of both genes and environment, separately or together, and allow valid inference to the population. These case-control-family designs (including those involving twin pairs), can be regarded as retrospective cohort studies of relatives, and can be used for: determining familial risks and genetic models; estimating risk (penetrance) for measured genotypes; genetic association studies; stratifying risks by family history and known mutation status; and studying modifiers of risk in genetically susceptible individuals. Follow-up of families allows genetic and environmental risks to be studied prospectively. We discuss statistical methods, theoretical and practical strengths, limitations, and other issues. Given their versatility, population-based family studies could become a principal framework in epidemiology, and move genetics from its traditional focus on high-risk families to give it a wider clinical and population health relevance.

Systematic review of the relationship between family history and lung cancer risk

We performed a systematic review of 28 case-control, 17 cohort and seven twin studies of the relationship between family history and risk of lung cancer and a meta-analysis of risk estimates. Data from both case-control and cohort studies show a significantly increased lung cancer risk associated with having an affected relative. Risk appears to be greater in relatives of cases diagnosed at a young age and in those with multiple affected family members. Increased lung cancer risk was observed in association with an affected spouse and twin studies, while limited, favour shared environmental exposures. The limitations of the currently published epidemiological studies to infer genetic susceptibility are discussed.

Familial risks for nonmedullary thyroid cancer

CONTEXT

Reliable data on familial risks are important for clinical counseling and cancer genetics.

OBJECTIVE

We wanted to define familial risks for histopathology-specific nonmedullary thyroid cancers through parental and sibling probands.

SETTING

The study examines the nationwide Swedish Family-Cancer Database on 10.5 million individuals, containing families with parents and offspring.

PATIENTS

Cancer data were retrieved from the Swedish Cancer Registry from years 1958 to 2002, including 3292 patients with thyroid adenocarcinoma. The Systematized Nomenclature of Medicine histology was available from 1993 onward, with 1449 papillary, 288 follicular, 148 anaplastic, and 68 Hurthle cell tumors.

MAIN OUTCOME MEASURES

Familial risk for offspring was defined through standardized incidence ratio, adjusted for many variables.

RESULTS

The familial risk for papillary carcinoma was 3.21 and 6.24 when a parent and a sibling, respectively, were diagnosed with thyroid cancers. There was an apparent gender preference, particularly among sisters, whose risk was 11.19. The risks were highest for early onset cancers. Thyroid adenocarcinoma was shown to be associated with melanoma and connective tissue tumors, and probably also with neurinomas (schwannomas). Associations found in single comparisons with papillary thyroid cancer and other sites included right-sided colon, breast, ovarian, and kidney cancers. Hurthle cell tumors were associated with Hodgkin's and non-Hodgkin's lymphoma, but the numbers of cases were small.

CONCLUSIONS

The present findings were based on a limited number of cases, but they display a complex and heterogeneous pattern of familial nonmedullary thyroid cancer. The high risk for papillary carcinoma among women requires clinical attention, although the absolute risks for this rare cancer are still low.

Familial association of prostate cancer with other cancers in the Swedish Family-Cancer Database

BACKGROUND

Familial associations between cancer sites may implicate true familial clustering which is relevant for the identification of new cancer syndromes and for clinical counseling.

METHODS

We used the nation-wide Swedish Family-Cancer Database, containing 10,553 sons and 107,518 fathers with prostate cancer among a total of 170,000 cancer patients in the 0- to 70-year-old offspring generation and over 800,000 cancer patients in the parental generation. We calculated familial standardized incidence ratios (SIRs) and confidence intervals (CIs) for prostate cancers and other cancers in family members.

RESULTS

SIRs for prostate cancer were increased in sons when mothers were diagnosed with breast and ovarian cancers, and when siblings were diagnosed with Hodgkins disease (1.78, N = 18, 95% CI 1.05-2.82) and leukemia (1.39, 43, 1.01-1.88). Liver cancer and melanoma were also in excess in the high-risk families.

CONCLUSIONS

The present analysis, the largest yet carried out, found many novel associations implying familial links between prostate cancer and other sites.

Population-Based Analysis of Prognostic Factors and Survival in Familial Melanoma

Purpose

Familial melanoma patients are reported to present with thinner melanomas, to be younger at the time of diagnosis, and to have a greater likelihood of developing multiple primary tumors. We sought to determine whether melanomas that occur in a familial setting demonstrate different prognostic and survival statistics relative to sporadic melanoma.

Patients and Methods

This population-based study used the Utah Cancer Registry and Utah Population Database to objectively evaluate prognostic and survival statistics of the familial melanoma population. From 1973 to 1999, there were 7,785 cases of invasive melanoma identified through the Utah Cancer Registry. These were linked to the Utah Population Database, resulting in 2,659 subjects with family-history information from which a familiality score could be calculated. Cases scored in the top ninth percentile were assigned as high familial risk, and the remaining 91% were considered low familial risk.

Results

Multivariate logistic-regression analysis found no association between sex, Breslow depth, Clark level, or survival and the familial status. Age at first diagnosis of invasive melanoma was slightly lower in the high-familial-risk group (57 v 60 years; P = .03). High-familial-risk subjects had more melanomas diagnosed at age 30 or younger (12% v 6%; P < .001). A significant difference in the overall number of individuals with two or more primary malignant melanomas was not detected among the groups (P = .2).

Conclusion

These data suggest that melanomas occurring in the context of an underlying inherited susceptibility do not have a significantly different biologic behavior.

Key concepts in genetic epidemiology

This article is the first in a series of seven that will provide an overview of central concepts and topical issues in modern genetic epidemiology. In this article, we provide an overall framework for investigating the role of familial factors, especially genetic determinants, in the causation of complex diseases such as diabetes. The discrete steps of the framework to be outlined integrate the biological science underlying modern genetics and the population science underpinning mainstream epidemiology. In keeping with the broad readership of The Lancet and the diverse background of today's genetic epidemiologists, we provide introductory sections to equip readers with basic concepts and vocabulary. We anticipate that, depending on their professional background and specialist knowledge, some readers will wish to skip some of this article.

Population-based risk assessment for other cancers in relatives of hereditary prostate cancer (HPC) cases

BACKGROUND

To identify associations of other cancers with hereditary prostate cancer (HPC) we estimated relative risks (RRs) of 36 different cancers in relatives of prostate cancer cases in the Utah Population Data Base (UPDB), which combines genealogical and cancer data for Utah.

METHODS

We utilized known genetic relationships between prostate cancer cases and their relatives with cancer, combined with age- and sex-specific cancer rates calculated internally from the UPDB, to estimate RRs for cancer in relatives of prostate cancer cases.

RESULTS

Multiple other cancers were observed in excess in both first- and second-degree relatives of HPC cases including colon cancer, non-Hodgkins lymphoma, multiple myeloma, rectal cancer, cancer of the gallbladder, and melanoma (skin).

CONCLUSIONS

This analysis supports the existence of heritable prostate cancer syndromes that include other cancers. We hypothesize that the study of homogeneous pedigrees co-segregating prostate cancer and another cancer could allow more straightforward localization and identification of the gene(s) responsible.

Radiosensitivity detected by the micronucleus test is not generally increased in sporadic prostate cancer patients

The micronucleus test (MNT) has shown increased micronuclei (MN) frequencies in BRCA associated and sporadic breast cancer patients, Ataxia telangiectasia and Nijmegen Breakage Syndrome patients, demonstrating a common cellular phenotype of increased radiosensitivity. Some genes, causative of these diseases, have also recently been associated with prostate cancer. In order to investigate if prostate cancer exhibits the cellular phenotype of increased radiosensitivity, we performed MNT analysis on 22 sporadic prostate cancer patients and 43 male controls. We determined the baseline MN frequency, in order to see in vivo chromosomal damage without radiation, and induced (after irradiation with 2 Gy) frequency of MN, both in binucleated cells (BNC) obtained from cultured peripheral blood lymphocytes. An automated image analysis system was used to score the MN employing two different classifiers (Classifier A and B) for detection of BNC. The mean baseline frequencies were 48/43 MN/1000 BNC (A/B) for the controls and 42/50 (A/B) for prostate cancer patients. The induced MN frequencies amounted to 107/111 MN/1000 BNC (A/B) for controls and 111/114 MN/1000 BNC (A/B) for prostate cancer patients. The obtained MN frequencies did not result in a statistically significant difference between unselected cases and controls. However, restricting the analysis to young patients (50-60 years, N = 7) and age-matched controls (N = 7) revealed marginally significant higher MN frequencies in patients. We conclude that increased radiosensitivity is not a property of prostate cancer patients in general.

Radiation exposure and familial aggregation of cancers as risk factors for colorectal cancer after radioiodine treatment for thyroid carcinoma

PURPOSE

In thyroid cancer patients, radioiodine treatment has been shown to be associated with an increased risk of colon carcinoma. The aim of this study in thyroid cancer patients was to evaluate the role of familial factors in the risk of colorectal cancer and their potential interaction with radioiodine exposure.

METHODS AND MATERIALS

We performed a case-control study on 15 colorectal cancer patients and 76 matched control subjects, nested in a cohort of 3708 thyroid cancer patients treated between 1933 and 1998. For each patient, the radiation dose delivered to the colon by radioiodine was estimated by use of standard tables. In those who received external radiation therapy, the average radiation doses delivered to the colon and rectum were estimated by use of DOS_Eg software. A complete familial history was obtained by face-to-face interviews, and a familial index was defined to evaluate the degree of familial aggregation.

RESULTS

The risk of colorectal cancer increased with familial aggregation of colorectal cancer (p = 0.02). After adjustment for the radiation dose delivered to the colon and rectum, the risk of colorectal cancer was 2.8-fold higher (95% CI, 1.0-8.0) for patients with at least one relative affected by colorectal cancer than for patients without such a family history (p = 0.05). The radiation dose delivered to the colon and rectum by (131)I and external radiation therapy was associated with an increase of risk near the significance threshold (p = 0.1). No significant interaction was found between radiation dose and having an affected relative (p = 0.9).

CONCLUSIONS

The role of familial background in the risk of colorectal cancer following a differentiated thyroid carcinoma appears to increase with the radiation dose delivered to the colon and rectum. However, the study population was small and no interaction was found between these two factors.

Gastric cancer: new genetic developments

Gastric cancer's (GC) incidence shows large geographic differences worldwide with the lowest rates occurring in most Western industrialized countries including the United States and the United Kingdom; in contrast, relatively high rates of GC occur in Japan, Korea, China, and South America, particularly Chile. The Laurén classification system classifies GC under two major histopathological variants: 1) an intestinal type and 2) a diffuse type. The intestinal type is more common in the general population, more likely to be sporadic and related to environmental factors such as diet, particularly salted fish and meat as well as smoked foods, cigarette smoking, and alcohol use. It exhibits components of glandular, solid, or intestinal architecture, as well as tubular structures. On the other hand, the diffuse type is more likely to have a primary genetic etiology, a subset of which, known as hereditary diffuse gastric cancer (HDGC), is due to the E-cadherin (CDH1) germline mutation. The diffuse type pathology is characterized by poorly cohesive clusters of cells which infiltrate the gastric wall, leading to its widespread thickening and rigidity of the gastric wall, known as linitis plastica. Helicobacter pylori infection is associated with risk for both the intestinal and diffuse varieties of gastric cancer. Germline truncating mutations of the CDH1 gene, which codes for the E-cadherin protein, were initially identified in three Maori families from New Zealand that were predisposed to diffuse GC. Since then, similar mutations have been described in more than 40 additional HDGC families of diverse ethnic backgrounds. It is noteworthy that two-thirds of HDGC families reported to date have proved negative for the CDH1 germline mutation. A number of candidate genes have been identified through analysis of the molecular biology of E-cadherin. Patients with evidence of the CDH1 germline mutation in the context of a family history of HDGC must be considered as candidates for prophylactic gastrectomy, given the extreme difficulty in its early diagnosis and its exceedingly poor prognosis when there is regional or distant spread. Specifically, the E-cadherin cytoplasmic tail interacts with catenins, assembling the cell-adhesion complex involved with E-cadherin mediated cell:cell adhesion. Beta-catenin and gamma-catenin compete for the same binding site on the E-cadherin cytoplasmic tail, directly linking the adhesion complex to the cytoskeleton through alpha-catenin. Beta-catenin gene (CTNNB1) mutations have been described predominantly in intestinal-type gastric cancers and CTNNB1 gene amplification and overexpression have recently been described in a mixed-type gastric cancer. This paper reviews the genetics of both intestinal and diffuse types of gastric carcinoma, their differential diagnosis, molecular genetics, pathology, and, when known, their mode of genetic transmission within families.

Risk of prostate cancer and family history of cancer: a population-based study in China

We evaluated prostate cancer risk and family history of cancers using data from a case-control study in China. Cancer information among first-degree relatives was collected from 709 subjects (238 cases and 471 controls). None of the subjects reported a family history of prostate cancer. However, excess prostate cancer risk was associated with a family history of any cancer (OR = 1.79, 95% CI: 1.21-2.63) and esophageal cancer (OR = 2.39, 95% CI: 1.15-5.00). Nonsignificant risk was seen for family history of cancers of the stomach, lung, and female breast. Our results did not confirm the familial tendency toward prostate cancer but other cancers prevalent in China appeared to be aggregate, particularly esophageal cancer. Larger studies are needed to confirm these findings, and to clarify the genetic and lifestyle factors that may be involved.

A cohort study of cancer risk in relation to family histories of cancer in the Utah population database

BACKGROUND

It is well known that genetic variability affects the risk of many cancers, but details of the patterning of inherited cancer risk across different sites and age groups still are not well quantified.

METHODS

The authors conducted a nested case-control study of the familial risk of 40 cancers based on a cohort of 662,515 individuals from the Utah Population Database. From 1 to 10 controls selected from the cohort were matched individually on gender, birth year, and birthplace to each cancer case; and familial standardized incidence ratios (FSIR) were calculated for both cases and controls. Conditional logistic regression was used to estimate relative risks and population-attributable risks (PARs) of cancer in relation to FSIR. Relative risks of cancer in first-degree through fifth-degree relatives of cases, compared with controls, were calculated using the proportional hazards methods. All analyses were adjusted for spouse affection status and Latter Day Saints church affiliation.

RESULTS

Thirty-five of 40 cancers exhibited positive associations between risk and FSIR, and 21 of those associations were statistically significant. PAR estimates were strikingly high for prostate carcinoma (57%), breast carcinoma (39%), colon carcinoma (32%), lip carcinoma (31%), chronic lymphocytic leukemia (35%), and melanoma (32%). Both the proportion and the number of all cancers attributable to family history peaked at 32% in the group ages 65-84 years and remained high in the group age >/= 85 years.

CONCLUSIONS

A substantial portion of cancer risk was attributable to familial factors. The patterns of familial cancer recurrence among distant relatives suggested that simple genetic mechanisms may explain much of the familiality of cancer.

Familial and Hereditary Prostate Cancer by Definition in an Italian Surgical Series: Clinical Features and Outcome

OBJECTIVE

To evaluate the clinical impact of different definitions of hereditary prostate cancer (PCa), the relative risk (RR) of relatives of PCa cases and differences in clinical-pathological features and outcome as function of a family history in a surgical series exposed to Mediterranean diet.

METHODS

We classified as Sporadic (SPC), Familial (FPC) or Hereditary (HPC) 606 consecutive PCa cases, 65 years old or less at diagnosis, underwent radical retropubic prostatectomy between January 1, 1987 and December 31, 2002 (mean follow-up: 6.4 years). The disease-free, overall and PCa-specific survival were also compared between SPC and non-SPC (NSPC) cases.

RESULTS

Overall 12.5% of cases had a positive family history. We found 14 (2.3%) HPC cases versus 16 (2.6%) taking account of X-linked transmission. Relatives of early-onset PCa cases had a higher RR to PCa (4.3) compared to late-onset PCa cases. NSPC cases had a lower frequency of positive margins status (p=0.011), perineural infiltration (p=0.028) and positive lymph nodes (p=0.005) than SPC cases, but no differences were found in major prognostic factors (preoperative PSA, Gleason sum, pathological stage) and outcome endpoints as function of a family history.

CONCLUSIONS

A positive family history is an important risk factor to PCa. HPC frequency is probably underestimated because of exclusion of X-linked transmission. We support the similarity between SPC and NSPC with respect to biological aggressiveness.

Familial nonmedullary thyroid cancer

Familial nonmedullary thyroid cancer (FNMTC) is a syndrome of familial clustering of thyroid cancers of follicular cell origin. It is characterized by multifocality, early onset, more recurrences, and a higher degree of aggressiveness than nonfamilial thyroid cancers of follicular cell origin. An autosomal dominant inheritance pattern with reduced penetrance appears likely in most pedigrees. Although several candidate genes responsible for isolated clinical variants of FNMTC have been identified in single families, the gene(s) responsible for the vast majority of FNMTC cases has yet to be identified. Members of FNMTC cohorts should be followed longitudinally with physical examination and ultrasonography, and aggressively treated when cancer is diagnosed. When cancer is diagnosed, total thyroidectomy should be performed, and most patients should have a prophylactic central neck dissection and a therapeutic lateral functional neck dissection, postoperative radioiodine ablation and thyroid-stimulating hormone (TSH) suppressive therapy. Close follow-up with stimulated thyroglobulin levels, neck ultrasounds, and radioiodine scans are also central to the management strategy.

Family History of Cancer, Its Combination with Smoking and Drinking, and Risk of Squamous Cell Carcinoma of the Esophagus

We analyzed the association between history of cancer in first-degree relatives and the risk of squamous cell carcinoma of the esophagus (SCCE) using data from three case-control studies conducted in Italy and Switzerland on 805 incident, histologically confirmed SCCE, and 3,461 hospital controls. The alcohol- and tobacco-adjusted odds ratio (OR) for a family history of esophageal cancer was 3.2 [95% confidence interval (CI), 1.7-6.2], and the OR was higher when the affected relative was a brother or was diagnosed at age <55 years. Compared to subjects without family history of esophageal cancer, non-current smokers, drinking <49 drinks per week, the OR was 2.9 (95% CI, 1.1-7.5) for family history alone, 15.5 (95% CI, 11.7-20.5) for current smokers drinking > or = 49 drinks per week without family history of esophageal cancer, and 107.0 (95% CI, 13.0-880.2) for current smokers drinking > or = 49 drinks per week who also had a family history of esophageal cancer. The risk of SCCE was also increased in subjects with a family history of cancer of the oral cavity/pharynx (OR, 3.7; 95% CI, 1.5-9.0) and stomach (OR, 2.0; 95% CI, 1.1-3.6), but not of other cancers, nor for a family history of any cancer (OR, 1.0; 95% CI, 0.8-1.4). These data show that, as for many other epithelial cancers, the risk of SCCE is increased in subjects with a family history of the disease, and that--in Western countries--avoidance of alcohol and tobacco is also the best way to prevent SCCE in subjects with a family history of the disease.

Clinical genetic counselling for familial cancers requires reliable data on familial cancer risks and general action plans

Familial cancer clustering, without obvious heritability, poses a major challenge for current cancer risk assessment and management. Reliable determination of familial risks for cancer is important for clinical genetic counselling, but medically verified data on familial risks for many malignancies have been limited. However, the nationwide Swedish Family-Cancer Database allows a reliable characterisation of familial risk for all major neoplasms. Even though alert genetic counsellors and certainly clinical cancer geneticists will consider familial cancer clustering in their purview, the standard medical referral systems, which have already been shown to be poor in capturing and referring families at high risk for heritable cancers, are unlikely to ascertain familial aggregations of other cancers that are not known to belong to an inherited cancer syndrome. The data will be helpful in implementing evidence based guidelines for helping the general medical system to ascertain and refer even familial cancer clusters to cancer genetics professionals.

Familial risk for non-Hodgkin lymphoma and other lymphoproliferative malignancies by histopathologic subtype: the Swedish Family-Cancer Database

Non-Hodgkin lymphoma (NHL) consists of a heterogeneous group of tumors. Population-based data on the familial risk for specific histopathologic subtypes have not been established. Such data are useful for clinical counseling and for searching tumor subtypes sharing common genetic pathways. We used the Swedish Family-Cancer Database to calculate standardized incidence ratios (SIRs) for histopathology-specific subtypes of NHL in 4455 offspring with NHL whose parents or siblings were affected with different types of lymphoproliferative malignancies. A familial history of NHL significantly increased the risk for NHL (SIRparent = 1.8; SIRsibling = 1.9) and for diffuse large B-cell lymphoma (SIRparent = 2.3), follicular lymphoma (SIRsibling = 2.3), and B-cell lymphoma not otherwise specified (NOS) (SIRsibling = 3.4). For a parental history of histopathology-specific concordant cancer, the risks were significantly increased for diffuse large B-cell lymphoma (SIR = 11.8), follicular NHL (SIR = 6.1), plasma cell myeloma (SIR = 2.5), and chronic lymphocytic leukemia (SIR = 5.9). Familial clusters for NHL seemed stronger in females and in siblings. Our study provides the first quantification of the familial risks for NHL by histopathology. The present findings give evidence for a strong familial association of NHL, with little differences in the magnitude of risks for various histopathologic subtypes. The patterns of risks in parents and siblings support the hypothesis of an autosomal-dominant component for diffuse large B-cell NHL and a recessive one for follicular NHL.

Hereditary Predisposition and Prostate Cancer

A genetic component in prostate cancer (PCa) has been recognized for decades, and much evidence has been accumulated in favor of a significant, but heterogeneous hereditary component in PCa.

Purpose

We studied the incidence of the familial and hereditary forms of PCa in our population of patients with a diagnosis of PCa clinically localized and age at diagnosis <65 yrs. Materials and methods: We administered a questionnaire to 667 patients submitted to radical prostatectomy from July 1978 to December 2002, obtaining a complete familial oncological anamnesis in 499 patients. The patients were followed-up until death or until 30 June 2004. Patients were classified into three categories according to Carter: familial, hereditary and sporadic PCa.

Results

A positive family history for PCa was found in 72 patients (14.4%). In 15 patients (3%), we observed a hereditary form of PCa and in 57 patients (11.4%) a familial form. Patients with hereditary PCa had a lower age at diagnosis (55 yrs). Genealogical pedigrees ruled out mendelian dominant autosomical transmission. No difference was found in the preoperatory, clinical and pathological features among the three PCa groups. A statistically significant familial association was found between PCa and cancer of breast and uterus.

Conclusions

This study supports evidence of a hereditary predisposition to PCa and the suggestion that an excess familial risk of PCa is due to the inheritance of multiple moderate-risk genetic variants.

CLL family ‘Pedigree 14’ revisited: 1947–2004

The notion that inherited predisposition contributes to the development of haematological malignancies is generally thought of as being a relatively new idea. However, Videbaek made a clear enunciation of such a hypothesis in 1947, from a study of tumour incidence in relatives of patients with different leukaemias. To gain further insight into inherited susceptibility to chronic lymphocytic leukaemia (CLL), we followed up the descendants of Videbaek's 'Pedigree 14' series of families. Using the Danish medical and pedigree databases, complete tracing of 222 descendants of the original 57 family members was achieved. To date, 10 family members have been diagnosed with CLL, one with T-cell lymphoma and 17 with nonhaematological cancers, including five with breast cancer. The detailed follow up of this family provides further support for inherited predisposition to CLL and illustrates the value of follow-up studies of previously published family material for genetic analyses.

Gastric adenocarcinoma: review and considerations for future directions

OBJECTIVE

This update reviews the epidemiology and surgical management, and the controversies of gastric adenocarcinoma. We provide the relevance of outcome data to surgical decision-making and discuss the application of gene-expression analysis to clinical practice.

SUMMARY BACKGROUND DATA

Gastric cancer mortality rates have remained relatively unchanged over the past 30 years, and gastric cancer continues to be one of the leading causes of cancer-related death. Well-conducted studies have stimulated changes to surgical decision-making and technique. Microarray studies linked to predictive outcome models are poised to advance our understanding of the biologic behavior of gastric cancer and improve surgical management and outcome.

METHODS

We performed a review of the English gastric adenocarcinoma medical literature (1980-2003). This review included epidemiology, pathology and staging, surgical management, issues and controversies in management, prognostic variables, and the application of outcome models to gastric cancer. The results of DNA microarray analysis in various cancers and its predictive abilities in gastric cancer are considered.

RESULTS

Prognostic studies have provided valuable data to better the understanding of gastric cancer. These studies have contributed to improved surgical technique, more accurate pathologic characterization, and the identification of clinically useful prognostic markers. The application of microarray analysis linked to predictive models will provide a molecular understanding of the biology driving gastric cancer.

CONCLUSIONS

Predictive models generate important information allowing a logical evolution in the surgical and pathologic understanding and therapy for gastric cancer. However, a greater understanding of the molecular changes associated with gastric cancer is needed to guide surgical and medical therapy.

Organizing population data into complex family pedigrees: application of a second-order data linkage to state birth defects registries

Researchers and health officials are increasingly using electronic linkage of large-scale health data systems as a tool for assembling a comprehensive picture of birth defects at a population level. Current linkage and database techniques are limited to first-order linkage--linking information on a single individual in one database with information on that same individual in another database. For example, while current strategies may indicate whether a child with a certain birth defect also has a specific metabolic disorder or risk factor, they are unable to readily determine whether he or she also has any siblings or other relatives with the same pattern. In contrast, the current manuscript proposes a second-order linkage--one that organizes data so that individual-level data can readily be organized into families or extended family pedigrees across an entire population. The ability to link and organize population data into family pedigrees can have significant, broad impact upon health research and service delivery. This can lead to large-scale analysis of genetic factors and, with the linking of environmental data, the potential for large-scale studies of gene-environment interactions. In addition, it expands the potential for epidemiological research by readily allowing the examination of familial effects upon population rates of birth defects, and provides valuable information that can assist in applied public health. An example of a second order database incorporating an electronic birth defects registry is presented.

Clonal lymphocytes in persons without known chronic lymphocytic leukemia (CLL): implications of recent findings in family members of CLL patients

Several genetic abnormalities have been characterized in chronic lymphocytic leukemia (CLL) but these are predominantly secondary events and the initiating phenomena in the etiology of the disease are yet to be established. Studies of inherited susceptibility have identified the early oncogenic events in both familial and "sporadic" forms of several malignant disorders, and this may also be possible in CLL. However, the utility of linkage analysis in identifying a predisposition locus for the disease is limited because large multigenerational families segregating CLL are rare, while the more frequent small nuclear CLL families contain insufficient numbers of affected individuals. The power to detect predisposition gene(s) could be greatly increased by extending the number of affected individuals within a particular family, for example, by identifying family members with subclinical levels of disease. High-sensitivity flow cytometry techniques, developed to monitor disease in CLL patients undergoing treatment, have allowed accurate enumeration of subclinical levels of CLL cells in healthy individuals from the general population and CLL families. Emerging evidence confirms the phenotypic, genotypic, and clinical associations between the aberrant cells in healthy individuals and those in CLL patients. The data suggest that inherited factors increase the susceptibility to both indolent and aggressive CLL, and they provide unbiased demonstration that the age of onset in CLL families is younger than in the general population.

The Swedish family-cancer database: update, application to colorectal cancer and clinical relevance

The Swedish Family-Cancer Database has been used for almost 10 years in the study of familial risks at all common sites. In the present paper we describe some main features of version VI of this Database, assembled in 2004. This update included all Swedes born in 1932 and later (offspring) with their biological parents, a total of 10.5 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry from 1958-2002, including over 1.2 million first and multiple primary cancers and in situ tumours. Compared to previous versions, only 6.0% of deceased offspring with a cancer diagnosis lack any parental information. We show one application of the Database in the study of familial risks in colorectal adenocarcinoma, with defined age-group and anatomic site specific analyses. Familial standardized incidence ratios (SIRs) were determined for offspring when parents or sibling were diagnosed with colon or rectal cancer. As a novel finding it was shown that risks for siblings were higher than those for offspring of affected parents. The excess risk was limited to colon cancer and particularly to right-sided colon cancer. The SIRs for colon cancer in age matched populations were 2.58 when parents were probands and 3.81 when siblings were probands; for right-sided colon cancer the SIRs were 3.66 and 7.53, respectively. Thus the familial excess (SIR-1.00) was more than two fold higher for right-sided colon cancer. Colon and rectal cancers appeared to be distinguished between high-penetrant and recessive conditions that only affect the colon, whereas low-penetrant familial effects are shared by the two sites. Epidemiological studies can be used to generate clinical estimates for familial risk, conditioned on numbers of affected family members and their ages of onset. Useful risk estimates have been developed for familial breast and prostate cancers. Reliable risk estimates for other cancers should also be seriously considered for routine clinical recommendations, because practically all cancers show a familial effect and the risks are high for some of the rare neoplasms. The implementation of a unified management plan for familial cancers at large will be a major challenge to the clinical genetic counselling community.

Family history of cancer and the risk of prostate cancer and benign prostatic hyperplasia

We analysed the relation between family history of cancer in first-degree relatives and risk of prostate cancer (PC) and benign prostatic hyperplasia (BPH) using data from a multicentric case-control study conducted in Italy from 1991 to 2002 on 1,294 cases of incident, histologically confirmed PC, 1,369 cases of BPH and 1,451 men admitted to the same network of hospitals for acute, nonneoplastic conditions. Unconditional logistic regression was used to estimate odds ratios (OR) of PC and BPH, adjusted for age and other confounders. Men with a family history of PC had an OR of PC of 4.0 (95% confidence interval [CI] 2.5-6.5), and the risk was higher when the proband was younger, when 2 or more relatives were affected or when the affected relative was a brother. The risk of PC was also increased in men with a family history of cancer of the ovary (OR = 6.2, 95% CI 1.2-32), bladder (OR = 3.5, 95% CI 1.6-7.4) and kidney (OR = 3.1, 95% CI 1.1-8.5). An involvement of breast/ovarian cancer predisposition genes in a small proportion of PCs was suggested by the cluster of these cancers in female relatives of a few PC cases. The risk of BPH was increased in men with a family history of bladder cancer (OR = 2.2, 95% CI 1.0-5.0) but not PC (OR = 1.2, 95% CI 0.7-2.2). Our study adds further information on the association of family history of cancer and risk of PC and is, to our knowledge, the first comprehensive epidemiologic information on family history of cancer and risk of BPH.

Familial association of colorectal adenocarcinoma with cancers at other sites

Data on the familial associations of colorectal cancer (CRC) of adenocarcinoma histology are limited, but they are of interest because they may give us clues about as yet unknown family clusters. We calculated standardised incidence ratios (SIRs) for right- and left-sided colon cancer and rectal cancer in offspring using data from the Swedish Family-Cancer Database covering familial tumours from 1991 to 2000. The offspring were at an increased risk of developing colon adenocarcinoma when parents presented with CRC (SIR 1.81), endometrial (SIR 1.52) and kidney (SIR 1.42) cancers. The SIRs in siblings were increased when a co-sibling was diagnosed with CRC (SIR 3.26), myeloma (SIR 2.65) and leukaemia (SIR 2.53). Right-sided colon cancer was associated with familial pancreatic, squamous cell skin cancers, thyroid gland cancer and Hodgkin's disease. Left-sided colon cancer was associated with testicular cancers. Rectal cancer was associated with cervical and genital cancers in mothers. Most of the findings were consistent with data on known cancer syndromes. A new association was noted where rectal cancer in offspring was related to cervical and female genital cancers in mothers through an unknown mechanism. Hodgkin's disease and myeloma were also associated with right-sided colon cancer in offspring. The association with carcinoma of the testis, renal parenchyma, skin and leukaemia need to be confirmed in an independent series.

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

BACKGROUND

The contribution of low-penetrant susceptibility variants to cancer is not clear. With the aim of searching for genetic factors that contribute to cancer at one or more sites in the body, we have analyzed familial aggregation of cancer in extended families based on all cancer cases diagnosed in Iceland over almost half a century.

METHODS AND FINDINGS

We have estimated risk ratios (RRs) of cancer for first- and up to fifth-degree relatives both within and between all types of cancers diagnosed in Iceland from 1955 to 2002 by linking patient information from the Icelandic Cancer Registry to an extensive genealogical database, containing all living Icelanders and most of their ancestors since the settlement of Iceland. We evaluated the significance of the familial clustering for each relationship separately, all relationships combined (first- to fifth-degree relatives) and for close (first- and second-degree) and distant (third- to fifth-degree) relatives. Most cancer sites demonstrate a significantly increased RR for the same cancer, beyond the nuclear family. Significantly increased familial clustering between different cancer sites is also documented in both close and distant relatives. Some of these associations have been suggested previously but others not.

CONCLUSION

We conclude that genetic factors are involved in the etiology of many cancers and that these factors are in some cases shared by different cancer sites. However, a significantly increased RR conferred upon mates of patients with cancer at some sites indicates that shared environment or nonrandom mating for certain risk factors also play a role in the familial clustering of cancer. Our results indicate that cancer is a complex, often non-site-specific disease for which increased risk extends beyond the nuclear family.

Descriptive epidemiology and risk factors for head and neck cancer

Although more common in developing countries, over 11,000 deaths will occur in the United States from head and neck cancer in 2004. Squamous cell carcinomas account for the vast majority of cases in the United States and the majority of these are related to exposure to tobacco and alcohol. Newer data suggest a genetic contribution. This group is the focus of primary and secondary preventative efforts.

Finding prostate cancer susceptibility genes

Prostate cancer is a heterogeneous disease with multiple loci contributing to susceptibility. Traditionally, genome-wide scans using high-risk families have utilized stratification by number of affected individuals, family history of other cancers, or family age at diagnosis to improve genetic homogeneity. In addition to locus heterogeneity, for later onset diseases such as prostate cancer, a major limitation to mapping efforts is that key parental DNA samples are rarely available. The lack of available samples from upper generations reduces inheritance information, and as a result, the standard 10-cM genome scan does not provide full power to detect linkage. To increase the ability to find disease-associated loci, much denser genome-wide scans must be undertaken in multiple ethnic groups. In addition, new ways of defining homogenous subsets of families need to be developed.

Evidence for a Heritable Component in Death Resulting From Aortic and Mitral Valve Diseases

Background— Cardiac valvular diseases contribute to >42 000 deaths yearly in the United States, but the role of genetics in these deaths is unknown. This study evaluated the familiality of death resulting from aortic, mitral, and all valvular diseases using a population-based genealogy linked to death records.

Methods and Results— The Utah Population Database contains >2 million individual records with genealogy data and 250 000 linked death certificates. Nonrheumatic aortic (n=932), mitral (n=1165), and all valvular (n=2504) disease deaths and rheumatic heart disease deaths (n=4713) were studied. Familial relative risks (FRRs) were assessed for first- and second-degree relatives. Familiality was also evaluated with the genealogical index of familiality, which considers all relationships in the Utah Population Database. FRRs were increased only for mitral valve death in both first-degree (FRR, 2.55; P <0.0001) and second-degree (FRR, 1.67; P <0.0001) relatives. Genealogical index of familiality analysis showed significant excess relatedness for all groups ( P <0.001). Genealogical index of familiality results ( P <0.001) for early age at death cases showed higher mean relatedness, a common characteristic of heritable disorders. Excess familiality extended to distant relatives for mitral (second-degree relatives) and aortic (beyond second-degree relatives) valve death.

Conclusions— Deaths resulting from nonrheumatic mitral and aortic diseases clustered among both close and distant relatives, especially among early age at death cases, suggesting a significant genetic component in death resulting from valvular diseases. Future studies should focus on gene discovery.

Hereditary risk factors for the development of gastric cancer in younger patients

BACKGROUND

It is believed that the development of gastric cancer (GC) before the age of 50 has a hereditary basis. Blood group A and history of gastric cancer in first-degree relatives have been shown to be risk factors for GC.

METHODS

In this case-control study, we enrolled patients with GC who were diagnosed before the age of 50. Patients who were diagnosed as having GC were selected. A total of 534 cases were found; of these, 44 diagnosed before the age of 50 were included in the case group. For the control group, 22 males and 22 females were randomly selected from the remaining subjects, who had diagnoses of GC after the age of 50. All the surviving patients and family members of the dead patients were interviewed about the history of cancer in the family and the age at which other family members developed cancer. The blood group of each subject was also obtained.

RESULTS

forty-four cases under 50 years old (mean age: 36.2 years) and forty-four controls (mean age: 67.1 years) were enrolled in the study. At the time of the study, 59.1% of the study group and 50% of the control group were alive (P value = NS). In the study group, 68.1%, 13.6%, 13.6% and 4.5% had blood groups O, A, B and AB, respectively. In the control group the corresponding figures were 27.7%, 63.6%, 6.8% and 4.5%. First or second-degree relatives with cancer, including gastric (the most frequent), breast, lung, gynecological and hematological malignancies, were noted in 54.5% of the cases and 11.4% of the controls (p < 0.01). Family histories of cancer were accepted as valid provided that they were based on valid medical documents.

CONCLUSIONS

It seems that the development of GC before the age of 50 is likely to be accompanied by familial susceptibility. Interestingly, our study showed a significant correlation between blood group O and the development of gastric cancer under the age of 50.

Molecular biology of prostate cancer

Development of any cancer reflects a progressive accumulation of alterations in various genes. Oncogenes, tumour suppressor genes, DNA repair genes and metastasis suppressor genes have been investigated in prostate cancer. Here, we review current understanding of the molecular biology of prostate cancer. Detailed understanding of the molecular basis of prostate cancer will provide insights into the aetiology and prognosis of the disease, and suggest avenues for therapeutic intervention in the future.

Genetic predisposition to colorectal cancer

High-penetrance mutations in several genes have been identified that contribute to hereditary colorectal cancer. The role of these mutations in cancer pathogenesis is well understood and their detection is successfully used in clinical diagnosis. In stark contrast, our understanding of the influence of low-penetrance mutations that account for most of the remaining familial cases of colorectal cancer, as well as an unknown proportion of sporadic cases, is far less advanced. Extensive ongoing research into low-penetrance, multifactorial predisposition to colorectal cancer is now beginning to bear fruit, with important implications for understanding disease aetiology and developing new diagnostic, preventive and therapeutic strategies.

Evidence for interaction between the TCO and NMTC1 loci in familial non-medullary thyroid cancer

BACKGROUND

Familial non-medullary thyroid cancer (fNMTC) is a complex genetic disorder that is more aggressive than its sporadic counterpart. Thus far, three genetic loci have been implicated in susceptibility to fNMTC by linkage analysis.

METHODS

We used linkage analysis to test the significance of two of the known susceptibility loci for fNMTC, TCO on 19p13 and NMTC1 on 2q21 in 10 fNMTC families, nine of which present with cell oxyphilia, a rare histological phenotype associated with TCO. Furthermore, we used two-locus linkage analysis to examine the possibility that the TCO and NMTC1 loci interact to increase the risk of NMTC.

RESULTS

The 10 families provided evidence for linkage at both TCO and NMTC, with LOD scores of 1.56 and 2.85, respectively. Two-locus linkage analysis, using a multiplicative risk model for the development of NMTC, achieved a maximum LOD of 3.92, with an LOD of 4.51 when assuming 70% of families were linked, indicating that the segregation in these families is consistent with an interaction model. Most of this evidence came from a large Tyrolean family that singularly achieved a two-locus LOD of 3.21.

CONCLUSIONS

These results provide further evidence that susceptibility genes for fNMTC exist at 19p13 and 2q21, and furthermore, raise the possibility that in a subset of fNMTC pedigrees, these loci interact resulting in significantly increased risk of NMTC for patients that carry both susceptibility loci.

Unravelling the genetics of prostate cancer

This review describes what is currently known about the genetics of prostate cancer. Traditionally, the genetics of a suspected inherited cancer predisposition have generally been thought of in terms of a single, high-risk gene with a dominant mode of inheritance. Such a gene might be observed in families, as has been documented in familial breast cancer (BRCA1/2), familial colorectal cancer (HNPCC), retinoblastoma (RB1), and Wilms tumor (WT1). This review investigates the evidence for the existence, first of familial prostate cancer, and second, for the presence of such a high-risk gene in those families by epidemiological and experimental approaches. Another current area of interest in prostate cancer is the investigation of the contribution of common lower penetrance genes to the disease. This alternative approach has become popular, as it raises the issue of frequently seen genetic variations such as single nucleotide polymorphisms (SNPs) having relevance to the risk of developing the disease. Finally, this article will explore the way forward, with emphasis on worldwide collaboration from teams attempting to find the genes responsible for the disease and investment in new technologies that will aid in their discovery.

Risk of Non-Hodgkin's Lymphoma and Family History of Lymphatic, Hematologic, and Other Cancers

Background: An elevated risk of developing non-Hodgkin's lymphoma (NHL) has been associated with a family history of NHL and several other malignancies, but the magnitude of risks and mechanisms are uncertain. Methods: We used self-reported family history data from a recent multicenter U.S.-based case-control studies of NHL to evaluate familial aggregation of NHL with various hematolymphoproliferative and other cancers. Estimates of familial aggregation were obtained as hazard ratios (HR) that compare incidence of different cancers in first-degree relatives of NHL cases with that in the first-degree relatives of NHL controls. Limitations of the study included low participation rates (76% for cases and 52% for controls) and potential differential accuracy of recall. Results: Risk of NHL was elevated in relatives of NHL cases [HR, 2.9; 95% confidence interval (95% CI), 0.95–8.53]; the aggregation seems to be stronger for siblings (HR, 7.6; 95% CI, 0.98–58.8) and for male relatives (HR, 6.2; 95% CI, 0.77–50.0). Risk of Hodgkin's lymphoma seems to be also elevated among relatives of early-onset (&lt;50 years) NHL cases (HR, 3.2; 95% CI, 0.88–11.6). Evaluation of family history of other cancers provided modest evidence for an increased risk of melanoma of the skin (HR, 2.9; 95% CI, 1.08–7.75), pancreatic cancer (HR, 2.1; 95% CI, 0.96–4.43), stomach cancer (HR, 1.8; 95% CI, 0.91–3.63), and prostate cancer (HR, 1.3; 95% CI, 0.87–1.99). Conclusions: These results are consistent with previous findings of familial aggregation of NHL, Hodgkin's lymphoma, and a few other cancers. The pattern of male-specific and sibling-specific familial aggregation of NHL we observed, if confirmed, may shed new light on the possible mechanisms that underlie familial aggregation of the disease.

Lifestyle and prostate cancer among older African-American and Caucasian men in South Carolina

OBJECTIVE

We investigated the association between lifestyle and prostate cancer risk among Caucasian and African-American men, separately.

METHODS

This population-based case-control study of prostate cancer among men aged 65-79 years was conducted between 2000 and 2002 in South Carolina. Telephone interviews were completed with 416 incident prostate cancer cases ascertained through the South Carolina Central Cancer Registry, and 429 controls identified through the Health Care Financing Administration Medicare beneficiary file (with respective response rates of 71% and 64%).

RESULTS

Caucasian men working in production, transportation, and material moving had increased prostate cancer risk (odds ratio [OR] = 2.04, 95% confidence interval [CI] 1.17-3.54), while African-American men in the military had reduced prostate cancer risk (OR = 0.19, 95% CI 0.05-0.76). Having five or more prostate specific antigen (PSA) tests within the past five years was associated with prostate cancer among Caucasian men; however, African-American men with prostate cancer tended to have fewer PSA tests. Increasing lycopene consumption was associated with a reduced risk of prostate cancer among Caucasian men (p = 0.03), but not among African-American men.

CONCLUSIONS

In this population-based case-control study conducted in South Carolina we did not find marked differences in lifestyle factors associated with prostate cancer by race.

Methods for testing familial aggregation of diseases in population-based samples: application to hodgkin lymphoma in swedish registry data

We use data on lymphoma in families of Hodgkin lymphoma (HL) cases from the Swedish Family Cancer Database (Hemminki et al. 2001) to illustrate survival methods for detecting familial aggregation in first degree relatives of case probands compared to first degree relatives of control probands, from registries that permit sampling of all cases. Because more than one case may occur in a given family, the first degree relatives of case probands are not necessarily independent, and we present procedures that allow for such dependence. A bootstrap procedure also accommodates matching of case and control probands by resampling the matching clusters, defined as the combined set of all first degree relatives of the matched case and control probands. Regarding families as independent sampling units leads to inferences based on "sandwich variance estimators" and accounts for dependencies from having more than one proband in a family, but not for matching. We compare these methods in analysis of familial aggregation of HL and also present simulations to compare survival analyses with analyses of binary outcome data.

Family history of hematopoietic and other cancers in children with acute lymphoblastic leukemia

It has been difficult to show a genetic contribution for many cancers, resulting in the belief that rare cancers such as leukemia are sporadic. We carried out a population-based case-control study including 701 incident cases of acute lymphoblastic leukemia (ALL) aged 0-14 years and diagnosed between 1980 and 1998 in Québec (Canada); 701 healthy controls were matched on age and sex. Cancer family history in the child's relatives was reported by parents. A positive family history of hematopoietic malignancies among first- or second-degree relatives was associated with a slight increase of risk for childhood ALL (odds ratio 2.06; 95% confidence interval=1.22-3.49); the excess was attributable to second-degree relatives, and observed for grandparents as well as for uncles/aunts. The risk of ALL was not increased in children with a family history of cancers other than hematopoietic cancers. The data suggest a modest familial contribution to childhood ALL.

Clinical characteristics of familial vs. sporadic non-Hodgkin lymphoma in patients diagnosed at the Mayo Clinic (1986-2000)

There are few data on the clinical characteristics of familial vs. sporadic non-Hodgkin lymphoma (NHL). Using the NHL registry at the Mayo Clinic, we compared age of diagnosis, gender, tumor site and histologic subtype between patients with sporadic and familial NHL. In 2001, we identified all new cases of adult NHL diagnosed between 1986 and 2000 in the Mayo Clinic NHL database (n = 2289) and mailed out a family history questionnaire to all living patients with a current address (n = 1043). Each NHL patient was categorized according to their self-report of leukemia or lymphoma in first-degree (1 degree) relatives. We received complete FH information on 740 patients (71%). Age at diagnosis of NHL ranged from 18-88 years (mean = 59 years) and 53% of our cases were male. First-degree FH of lymphoma was reported by 43 patients (6%), 1 degree FH of leukemia by 27 patients (4%) and 1 degree FH of both in 4 (1%). There was a nonstatistically significant later age at diagnosis for cases with any family history of lymphoma or leukemia (mean age = 61.3 and 61.7 years, respectively) vs. no family history (59.0 years) (P = 0.58). The male to female ratio for those with a FH of leukemia (ratio = 2.9) was higher compared to those with FH lymphoma (0.95) or no FH (1.1) (P = 0.08). No differences were apparent between 1 degree FH and site of NHL (nodal vs. extranodal) (P = 0.53). Among recently diagnosed cases (since 1995), there was some suggestion of a greater proportion of aggressive tumors for those with any family history (69% and 55%) vs. none (50%) (P = 0.20). We found little evidence of large differences between familial and sporadic NHL with regard to age, gender, site or histologic subtype.

The clinical genetics of prostate cancer

Prostate cancer is the most common cancer in men and the second highest cause of cancer-related mortality in the U.K. A genetic component in predisposition to prostate cancer has been recognized for decades. One of the strongest epidemiological risk factors for prostate cancer is a positive family history. The hunt for the genes that predispose to prostate cancer in families has been the focus of many research groups worldwide for the past 10 years. Both epidemiological and twin studies support a role for genetic predisposition to prostate cancer. Familial cancer loci have been found, but the genes that cause familial prostate cancer remain largely elusive. Unravelling the genetics of prostate cancer is challenging and is likely to involve the analysis of numerous predisposition genes. Current evidence supports the hypothesis that excess familial risk of prostate cancer could be due to the inheritance of multiple moderate-risk genetic variants. Although research on hereditary prostate cancer has improved our knowledge of the genetic aetiology of the disease, a lot of questions still remain unanswered.

This article explores the current evidence that there is a genetic component to the aetiology of prostate cancer and attempts to put into context the diverse findings that have been shown to be possibly associated with the development of hereditary prostate cancer. Linkage searches over the last decade are summarised. It explores issues as to why understanding the genetics of prostate cancer has been so difficult and why despite this, it is still a major focus of research. Finally, current and future management strategies of men with Hereditary Prostate Cancer (HPC) are discussed.

Familial malignant melanoma - overview

Approximately 3-15% of all malignant melanomas (MM) are familial cases. MM is a highly heterogeneous tumour type from a genetic perspective. Pedigrees with disease confined to a single generation of siblings or MM occurring among second- or third-degree relatives suggest multifactorial polygenic inheritance. However, not infrequently, within large families aggregations of MM are consistent with autosomal dominant inheritance, suggesting a hereditary syndrome caused by germline alterations of a single gene. Several different genes are involved in the development of MM. However, even when taken together they are responsible for less than 20% of all MM cases. It is thus necessary to perform association studies focused on genetic markers that could be used in identifying patients with a high risk of MM. Evaluation of aggregations of MM and other malignancies, like breast cancer, could be essential in identifying relatives of MM probands being at high risk of developing malignancies other than MM. The ultimate goal is to apply in these cases prevention recommendations and surveillance protocols to reduce the disease risk.

TNR/11q#1 Trinucleotide (GCC)n Repeat Alleles and Predisposition to Acute and Chronic Leukemia

TNR/11q#1 is a polymorphic trinucleotide (GCC)n repeat located within the minimal region of the 11q deletion in chronic lymphocytic leukemia (CLL). It was recently shown that certain alleles of this repeat are associated with a worse prognosis in CLL patients. To investigate the role of TNR/11q#1 variants as risk-modifying factors in leukemogenesis, we conducted a case-control study on 113 acute lymphotic leukemia (ALL) patients, 82 CLL patients and 146 healthy controls of Russian origin. Comparison of allele and genotype distributions in the control, ALL and CLL groups, performed by Fisher's exact test with two-sized P-value, showed significant decrease in the presence of the GCC(6) allele in the ALL and CLL groups compared to controls. Moreover, 'rare' alleles GCC(7-8) and GCC(13-14) were significantly overrepresented in the ALL group versus controls. We found that CLL risk genotypes were those with both alleles containing more than 6 GCC repeats (P = 0,0212, odds ratio = 1,68 (95% CI, 1,121...2,531)). ALL risk genotypes include three allele combination variants: 1) both alleles containing more than 6 GCC repeats (P = 0,0019, odds ratio = 1,756 (95% CI 1,223...2,502)); 2) one of the alleles containing 7 or 8 repeats (P = 0,0155, odds ratio = 18,22 (95% CI 1,93...136.37)); 3) one of the alleles containing more than 12 repeats (P = 0,0209, Odds ratio = 2,599 (95% CI 1,161...5,815)). Association of certain alleles and genotypes of the TNR/11q#1 repeat with both acute and chronic lymphocytic leukemia suggests the presence of a cancer related gene, involved in a wide spectrum of neoplasia, in the vicinity of this repeat.

Age-specific familial risks for renal cell carcinoma with evidence on recessive heritable effects

BACKGROUND

Systematic comparisons of mode of inheritance for renal cell carcinoma (RCC) have not been carried out. The occurrence of cancer in parents and offspring may be due to dominant causes, whereas cancer affecting only siblings may indicate a recessive causation. Environmental effects need to be excluded.

METHODS

The Swedish Family-Cancer Database includes all Swedes born after 1931 with their biologic parents, totaling 10.2 million persons. Cancer data were retrieved from the Swedish Cancer Registry from years 1961 to 2000, included 2415 cases of RCC in offspring and 18531 in parents. Standardized incidence ratios (SIRs) and 95% CI limits were calculated for offspring whose parents or sibling were diagnosed with RCC.

RESULTS

The SIRs for siblings for RCC depended on their age difference. SIR was 7.63 (95% CI 3.63-14.08) when the age difference was less than 3 years and compared to 3.43 (95% CI 1.77-6.02) for large age difference. SIRs for familial risk of RCC were 1.73 (95% CI 1.31-2.26) when a parent and 4.58 (95% CI 2.87-6.94) when a sibling had RCC. Age-specific analysis of familial RCC among siblings revealed maxima at ages 40 to 49 and 60 to 68 years.

CONCLUSION

The findings in the present study offer evidence on recessive effects in early onset RCC.

Familial aggregation of Hodgkin lymphoma and related tumors

BACKGROUND

The importance of genetic factors in the etiology of Hodgkin lymphoma (HL) has been suggested by family and population studies. However, the spectrum of malignancies associated with common genetic etiology and the effects of gender and age on familial risk have not been established.

METHODS

Diagnoses of lymphoproliferative malignancies were compared in 15,799 first-degree relatives of 5047 patients with HL versus 32,117 first-degree relatives of 10,078 control probands from Sweden and in 7185 first-degree relatives of 2429 patients with HL versus 27,434 first-degree relatives of 8,495 control probands from Denmark using marginal survival models.

RESULTS

The risk of HL in relatives of patients with HL was increased significantly in both populations, with relative risks of 3.47 (95% confidence interval [95% CI], 1.77-6.80) in Sweden and 2.55 (95% CI, 1.01-6.45) in Denmark and a pooled estimate of 3.11 (95%CI, 1.82-5.29). In Sweden, risks for relatives of patients also were increased significantly for chronic lymphocytic leukemia and non-Hodgkin lymphoma (in males). Relative risks were higher in males compared with females and in siblings of patients compared with parents and offspring of patients. Relatives of patients with earlier-onset disease were at higher risk for HL.

CONCLUSIONS

HL has an important familial component, which is stronger in families of affected individuals age < 40 years, in males, and in siblings, and it is shared with some (but not other) lymphoproliferative malignancies. The cumulative lifetime risks are very small, however, for the development of HL de novo or in first-degree relatives of affected patients.

Family history of benign thyroid disease and cancer and risk of thyroid cancer

In a population-based study of 313 case-control pairs in Kuwait, we evaluated whether a family history of benign thyroid disease (BTD) and thyroid or other cancers was associated with an increased risk of thyroid cancer, the second most common neoplasm among women in this and several other Arab countries in the Gulf region. Family history of BTD was reported by 78 (24.9%) cases and 40 (12.8%) controls in 132 and 57 relatives, respectively. There was an approximately 2-fold increased risk of thyroid cancer in individuals who had a mother (Odds Ratio (OR)=2.3; 95% Confidence Intervals (95% CI): 1.1-5.1), sister(s) (OR=2.6; 95% CI: 1.3-5.3) or aunt(s) (OR=2.1; 95% CI: 0.9-5.3) with BTD; there was also a significant trend in increasing risk with an increasing number of affected female relatives (P<0.0001). Stratification by age at diagnosis of the case showed that individuals aged </= 35 years, who had an affected first- or second/third-degree relative(s), had an approximately 3-fold increased risk of the cancer. Family history of thyroid cancer was reported by 9 (2.9%) cases in 13 relatives (11 females, 2 males) and by 3 controls in 3 relatives (all females) (OR=3.0; 95% CI: 0.8-11.1). The OR for all hormone-related cancers combined was 1.5 (95% CI: 0.8-2.6). There was no clear association with family history of breast or any other common cancer. Our data suggest that a family history of BTD is associated with an increased risk of thyroid cancer, and point to the role of familial susceptibility to BTD and thyroid cancer in the Kuwaiti population.