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

Family history and the risk of prostate cancer

OBJECTIVES

Several studies have identified prostate cancer family history as a risk factor for prostate cancer incidence, typically associated with a twofold to fourfold increase in risk. A family history of breast cancer has also been implicated. We investigated the associations between prostate cancer incidence and family histories of prostate and breast cancer, controlling for possible confounding due to environmental factors.

METHODS

Data from the random sample-based Massachusetts Male Aging Study cohort (1987 to 1997) were used. Incidence rates were calculated as the number of cases per person-year of follow-up. Covariates were adjusted for using Poisson regression.

RESULTS

Among 1149 men with an average of 8.7 person-years of follow-up, 57 were diagnosed with prostate cancer, 110 men reported a prostate cancer family history, and 157 reported a breast cancer family history. The age-adjusted relative risk (RR) of prostate cancer incidence associated with prostate cancer family history was 3.29 (95% confidence interval [CI] 1.82 to 5.94). No evidence of heterogeneity was found across age levels (P = 0.83). Additional adjusting for environmental factors such as smoking, alcohol use, body mass index, physical activity, education, sexually transmitted disease history, diet, and hormone levels yielded a slightly higher RR (3.78, 95% CI 1.96 to 7.28). No association with a family history of breast cancer was evident (RR = 1.18, 95% CI 0.51 to 2.43).

CONCLUSIONS

We found an association between prostate cancer incidence and a family history of prostate cancer, independent of environmental factors. No association with a family history of breast cancer was evident.

Familial nonmedullary thyroid cancer

Familial nonmedullary thyroid cancer is more aggressive than sporadic nonmedullary thyroid cancer. It tends to affect younger patients, and the tumors are often multi-focal and bilateral. Histologically, 90% of these tumors are papillary cancers and the remaining are Hürthle cell cancers. We recommend total thyroidectomy to remove all the thyroid tissue, which harbors the genetic defect responsible for the disease (even in low-risk patients) due to the predisposition to develop thyroid cancer and the more aggressive nature of the disease. Careful exploration of the ipsilateral lymph nodes with ipsilateral central neck dissection is encouraged to decrease a high recurrence rate (44%). A complete modified radical neck dissection should be limited to a therapeutic role because there is no clear evidence that this procedure carries any survival benefit. We also recommend that patients receive radioactive iodine ablation post-operatively, including a prophylactic dose (30 mCi) for patients with no evidence of residual uptake on the postoperative iodine 131 whole body scan and in low-risk patients using any of the prognostic scoring systems. Patients should be placed on enough thyroid hormone to suppress thyroid-stimulating hormone (TSH) to approximately 0.1 mL/mL in low-risk patients and to less than 0.1 mL/mL in high-risk patients. Focal metastatic disease in patients with familial nonmedullary thyroid cancer is best dealt with by surgical excision followed by radioactive iodine ablation when appropriate. Redifferentiation therapy has a promising role in patients who have radioactive iodine-resistant tumors. The value of prevention, early detection, and targeted gene therapy once the gene or genes responsible for familial non-medullary thyroid cancer have been identified cannot be overemphasized.

Familial cancer risks in affected sibships: results from the Swedish family-cancer database

We used the nationwide Swedish Family-Cancer Database to assess familial risks to sibs in sibsibs where at least two sibs had concordant cancer and their parents either concordant or discordant cancer. Familial relative risks (FRRs) were calculated by comparing to concordant sib-pairs whose parents had no cancer. Cancer sites were included if at least ten such concordant sib-pairs were found. In situ cancers were included in order to increase the numbers of cases. Concordant triads, one parent and the sib-pair affected, had an FRR over 100 for thyroid (FRR 399), colon, all bowel, and ovarian cancer. In these cancers, some 40% or more of the concordant sib-pairs belonged to this group. Melanoma and cancer of the nervous system showed FRRs of about 20, and invasive breast cancer of only 2. 9; in these cancers no more than 10% of the concordant sib-pairs belonged to the concordant triads. Discordant family sets, one or two parents presenting with a cancer discordant from that of the sib-pair, showed an FRR of about 3.0 and breast cancer about 2.0, suggesting the involvement of familial effects shared by many forms of cancer.

Environmental and heritable factors in the causation of cancer--analyses of cohorts of twins from Sweden, Denmark, and Finland

BACKGROUND

The contribution of hereditary factors to the causation of sporadic cancer is unclear. Studies of twins make it possible to estimate the overall contribution of inherited genes to the development of malignant diseases.

METHODS

We combined data on 44,788 pairs of twins listed in the Swedish, Danish, and Finnish twin registries in order to assess the risks of cancer at 28 anatomical sites for the twins of persons with cancer. Statistical modeling was used to estimate the relative importance of heritable and environmental factors in causing cancer at 11 of those sites.

RESULTS

At least one cancer occurred in 10,803 persons among 9512 pairs of twins. An increased risk was found among the twins of affected persons for stomach, colorectal, lung, breast, and prostate cancer. Statistically significant effects of heritable factors were observed for prostate cancer (42 percent; 95 percent confidence interval, 29 to 50 percent), colorectal cancer (35 percent; 95 percent confidence interval, 10 to 48 percent), and breast cancer (27 percent; 95 percent confidence interval, 4 to 41 percent).

CONCLUSIONS

Inherited genetic factors make a minor contribution to susceptibility to most types of neoplasms. This finding indicates that the environment has the principal role in causing sporadic cancer. The relatively large effect of heritability in cancer at a few sites suggests major gaps in our knowledge of the genetics of cancer.

Evidence for a prostate cancer-susceptibility locus on chromosome 20

Recent studies suggest that hereditary prostate cancer is a complex disease involving multiple susceptibility genes and variable phenotypic expression. While conducting a genomewide search on 162 North American families with > or =3 members affected with prostate cancer (PRCA), we found evidence for linkage to chromosome 20q13 with two-point parametric LOD scores >1 at multiple sites, with the highest two-point LOD score of 2.69 for marker D20S196. The maximum multipoint NPL score for the entire data set was 3.02 (P=.002) at D20S887. On the basis of findings from previous reports, families were stratified by the presence (n=116) or absence (n=46) of male-to-male transmission, average age of diagnosis (<66 years, n=73; > or =66 years, n=89), and number of affected individuals (<5, n=101; > or =5, n=61) for further analysis. The strongest evidence of linkage was evident with the pedigrees having <5 family members affected with prostate cancer (multipoint NPL 3.22, P=.00079), a later average age of diagnosis (multipoint NPL 3.40, P=.0006), and no male-to-male transmission (multipoint NPL 3.94, P=.00007). The group of patients having all three of these characteristics (n=19) had a multipoint NPL score of 3.69 (P=.0001). These results demonstrate evidence for a PRCA susceptibility locus in a subset of families that is distinct from the groups more likely to be linked to previously identified loci.

Molecular mechanisms and pathways in bladder cancer development and progression

BACKGROUND

The basis for bladder cancer development and progression is complex and involves genetic abnormalities. These abnormalities yield phenotypic changes that allow normal transitional cells to become cancerous and finally acquire the "malignant phenotype."

METHODS

The authors review the most common genetic alterations in bladder cancer and the molecular mechanisms and pathways involved in the conversion of normal transitional cell into malignant transitional cancer cells.

RESULTS

There are several potential genetic changes of the urothelium that eventually cause bladder cancer initiation and tumor progression. Some of these alterations are also found in other malignancies suggesting that key common pathways exist in the development of cancer.

CONCLUSIONS

As the roles of certain genes or proteins are further elucidated, a better understanding of cancer development can aid in the prevention, diagnosis, and treatment of bladder cancer.

Increased cancer risk among relatives of nonsmoking lung cancer cases

Lung cancer has been shown to aggregate in families of nonsmoking lung cancer cases with an earlier age at onset. The current study evaluates whether relatives of nonsmoking lung cancer cases are at increased risk of cancers at sites other than lung. Families were identified through 257 population-based, nonsmoking lung cancer cases and 277 population-based, nonsmoking controls residing in metropolitan Detroit. Data were collected for 2,252 relatives of cases and 2,408 relatives of controls. First-degree relatives of nonsmoking lung cancer cases were at 1.52-fold (95% CI, 1.02-2.27) increased risk of cancer of the digestive system after adjustment for each relative's age, race, sex, and smoking status. Relative risk estimates also were elevated, but not significantly, for tobacco-related cancers (RR = 1.39) and breast cancer (RR = 1.72). Among first-degree relatives of younger probands (age 40-59), risk was non-significantly increased 72% (95% CI 0.95-3.10) for all cancers combined and 3.14-fold for cancers of the digestive system (95% CI 0.76-12.9). Nonsmoking relatives of cases were at increased risk of all cancer sites combined (RR = 1.32; 95% CI 1.003-1.73), cancers other than lung (RR = 1.37; 95% CI 1.03-1.82), and digestive system cancers (RR = 2.01; 95% CI 1.20-3.37). These findings of moderate familial aggregation for cancers of the lung, digestive system, breast, and tobacco-related sites suggest that common susceptibility genes may act to increase risk for a variety of cancers in families.

National database of familial cancer in Sweden

A family cancer database was constructed from the nationwide Swedish registries and includes approximately 6 million persons and >30,000 cancers in offspring diagnosed at ages 15-51 years and their parents. A particular advantage of the database is that the contribution of both parental lineages on cancer risk can be examined. Cancer risk in the offspring was increased approximately 1.1 times when the father had cancer, and no increase was noted when the mother had cancer. If both parents had cancer, the risk for sons was 1.4 and for daughters 1.3. The sites of increased cancer risk in the offspring were colorectum, breast, cervix, corpus uteri, ovary, testis, melanoma, eye, other endocrine glands, and multiple myeloma. The results among young and middle-age adults suggest that cancer in both parents increases the cancer risk in the offspring at many sites. The molecular genetic explanation may be that rare dominant single genes increase susceptibility at many sites, or that overlapping sets of genes control susceptibility at multiple sites.

Familial chronic lymphocytic leukaemia: a survey and review of published studies

B-cell chronic lymphocytic leukaemia (CLL) is the most common form of leukaemia. To gain insight into the role of inherited factors in the disease, we have conducted a survey of the family histories of 268 CLL patients and have reviewed published familial cases and epidemiological studies. The results of our survey and published studies strongly support the hypothesis that a subset of the disease can be ascribed to a genetic predisposition. The most likely genetic model for inherited predisposition appears to be dominantly acting genes with pleiotropic effects because in many families CLL appears to be associated with other lymphoproliferative disorders.

New insights and candidate genes and their implications for care of patients with hereditary prostate cancer

A positive family history is a risk factor for prostate cancer. Most studies based on segregation analysis suggest autosomal dominant transmission of susceptibility genes. Multiple loci on chromosome 1 and chromosome X have been associated with prostate cancer by linkage analysis. The candidate gene approach has also revealed multiple genetic markers that are associated with increased risk for the disease. The genetic studies in prostate cancer suggest there are multiple genes involved in the development and progression of prostate cancer.

Linkage analyses at the chromosome 1 loci 1q24-25 (HPC1), 1q42.2-43 (PCAP), and 1p36 (CAPB) in families with hereditary prostate cancer

Recent studies suggest that hereditary prostate cancer (PRCA) is a complex disease, involving multiple susceptibility genes and variable phenotypic expression. Through linkage analysis, potential prostate cancer susceptibility loci have been mapped to 3 regions on chromosome 1. To investigate the reported linkage to these regions, we conducted linkage studies on 144 PRCA families by using microsatellite markers in regions 1q24-25 (HPC1) and 1q42.2-43 (PCAP). We also examined the 1p36 (CAPB) region in 13 PRCA families with at least one case of brain cancer. No significant evidence of linkage to the HPC1 or PCAP region was found when the entire data set was analyzed. However, weak evidence for linkage to HPC1 was observed in the subset of families with male-to-male transmission (n=102; maximum multipoint nonparametric linkage [NPL] 1.99, P=.03). Weak evidence for linkage with heterogeneity within this subset was also observed (HLOD 1.21, P=.02), with approximately 20% of families linked. Although not statistically significant, suggestive evidence for linkage to PCAP was observed for the families (n=21) that met the three criteria of male-to-male transmission, average age of diagnosis <66 years, and >/=5 affected individuals (maximum multipoint NPL 1.45, P=.08). There was no evidence for linkage to CAPB in the brain cancer-prostate cancer subset. These results strengthen the argument that prostate cancer is a heterogeneous disease and that multiple genetic and environmental factors may be important for its etiology.

Familial prostate cancer from the family-cancer database

The aim of this study was to calculate the familial risk for prostate cancer (PC) for different family relationships. PC was studied in the Swedish Family-Cancer Database, updated in 1999 to cover individuals born after 1934 with their biological parents, totalling 9.6 million persons. Cancer data were obtained from the Swedish Cancer Registry from 1958 to 1996 and included 1035 PC cases amongst offspring. 188 families were identified where a father and a son had PC, giving a familial standardised incidence ratio (SIR) of 2.44 (2.10-2.80). The proportion of familial cancers was 18.2% amongst all PC amongst all PC amongst sons. There were only 5 pairs of affected brothers, of which 3 had an affected father. Age of onset modified familial risks modestly; the highest SIR of 4.43 (1.40-9.17) was for sons diagnosed before 50 years of age when the father was diagnosed before 65 years of age. When analysed across sites, an association of PC in one generation and stomach, liver and skin cancer and myeloma in another generation was observed. The link was most consistent for skin cancer. No maternal site was associated with a son's PC, although the SIR of breast cancer was 1.22 (0.95-1.53). No increased risk of malignancy was observed in wives of affected men excluding any shared environmental effect for PC and female cancers.

Familial associations between cancer sites

The Utah Population Database links together genealogical records, the Utah Cancer Registry, and Utah death certificates and allows identification of cancer clusters. Groups of individuals with cancers of some types tend to fall into related clusters within the genealogy. We examine the apparent tendency of cases of two types of cancer to cluster together and distinguish real clusters from chance occurrences. Some established associations are found, whereas some are surprisingly absent. Some new associations are also suggested.

Prostate cancer susceptibility locus HPC1 in Utah high-risk pedigrees

A prostate cancer susceptibility locus ( HPC1 ) at 1q24-25 has been identified. Subsequent analysis showed that the majority of the evidence for localization was provided by families with relatively young (<65 years) average age at diagnosis. We examined evidence for linkage to this region in a set of 41 extended multi-case prostate cancer pedigrees containing 440 prostate cancer cases. Genotyping of five short tandem repeat markers in the region was performed on DNA from 1724 individuals, including 284 prostate cancer cases. In comparison with the families reported in the initial localization, the Utah pedigrees are generally much larger (average of 10.7 versus 5.1 cases) and have an older average age at diagnosis (69 versus 65 years). Two- and three-point linkage analyses were conducted using a previously reported model and provided replication for HPC1 (two-point: LOD = 1.73, P = 0.005 at D1S196; three-point: LOD = 2.06, P = 0.002 for the interval D1S196-D1S416 ). The youngest quartile (by median age at diagnosis) yielded a maximum LOD of 2.82, P = 0. 0003 (at D1S215-D1S222 ), compared with a maximum LOD of 0.73, P = 0. 07 for the oldest quartile pedigrees at the same locus. Further analysis with an age-dependent model, specifying higher sporadic rates for older cases, suggests that the linkage evidence may be lower than expected given the power of the resource due to a high sporadic rate in the large Utah pedigrees.

Mapping of a gene predisposing to familial thyroid tumors with cell oxyphilia to chromosome 19 and exclusion of JUN B as a candidate gene

BACKGROUND

Familial nonmedullary thyroid carcinoma (FNMTC) is a clinical entity characterized by a more aggressive phenotype than the sporadic counterpart. The transmission of susceptibility of FNMTC is compatible with autosomal dominant inheritance. We report the identification of a new entity of FNMTC and the mapping of the responsible gene named TCO (for thyroid tumor with cell oxyphilia).

METHODS

In one family, multinodular goiters were diagnosed in six individuals and papillary thyroid carcinoma was diagnosed in three. Eight patients were operated on. Blood samples were collected from the nine affected patients and from eight unaffected relatives. The gene was mapped by linkage analysis with a whole-genome panel of microsatellite markers.

RESULTS

The neoplastic cells from all lesions showed characteristic faint to marked cytoplasmic oxyphilia. We found a logarithm of odd ratio (LOD) score of 2.41 at theta = 0 for marker D19S586. Additional markers were typed in the region and were found to be in linkage, with LOD scores peaking at markers D19S916 (Zmax = 3.01 at theta = 0) and D19S413 (Zmax = 2.95 at theta = 0). All these markers have been physically mapped to 19p13.2.

CONCLUSIONS

TCO was mapped to chromosome 19p13.2. Interestingly, both the benign and malignant thyroid tumors in this family exhibit some degree of oxyphilia, which has not been described until now in the familial forms of NMTC.

Family history of cancer, mutagen sensitivity, and increased risk of head and neck cancer

To evaluate individual cancer susceptibility, 170 previously untreated patients with pathologically-confirmed squamous cell carcinoma of the oral cavity, pharynx, and larynx, and 175 age- and sex-matched health controls were investigated for the occurrence of cancer in first-degree relatives along with other established risk factors for head and neck cancer. More than 54% of these subjects were assayed for mutagen sensitivity by quantifying in-vitro bleomycin-induced chromosomal breaks within peripheral blood lymphocytes. After adjusting for age, gender, education, family income, tobacco and alcohol consumption, the odds ratio associated with three or more first-degree relatives with cancer at any site was 3.79 (95% CI 0.9-15.9) with a linearly-increased trend in risk (P = 0.040). Significantly elevated risk was found to be associated with a history of cancer within siblings (OR = 2.61, 1.2-5.6, P = 0.014). Patients with a family cancer history and mutagen sensitivity were at greatest risk (OR = 7.88, 2.5-25.3, P = 0.005), indicating an additive interactive effect. The findings suggested that genetic familial influence is important in the causation of head and neck cancer.

Familial aggregation of breast cancer with early onset lung cancer

Site-specific familial aggregation and evidence supporting Mendelian codominant inheritance have been shown in lung cancer. In characterizing lung cancer families, a number of other cancers have been observed. The current study evaluates whether first-degree relatives of early onset lung cancer cases are at increased risk of breast cancer. Families were identified through population-based lung cancer cases and controls under 40 years of age. Cases were ascertained through the Metropolitan Detroit SEER registry; controls through random-digit dialing. Data were available for 384 female relatives of 118 cases and 465 female relatives of 161 controls. Breast cancer in relatives was evaluated after adjusting for age, race, sex, and smoking status of each family member and the sex and age of the probands. A positive family history of early onset lung cancer increased breast cancer risk among first-degree relatives 5. 1-fold (95% CI, 1.7-15.1). Relatives of cases with adenocarcinoma of the lung were at highest risk (RR = 6.3, 95% CI 2.0-20). Mean age of breast cancer diagnosis among relatives of cases was 52.2 years and not statistically different from relatives of controls. Three case families also reported early ovarian cancers (mean age of diagnosis of 35 years). These findings suggest that shared susceptibility genes may act to increase risk of early onset lung and breast cancer in families.

Familial risks in cervical cancer: is there a hereditary component?

The Swedish Family-Cancer Database was used to analyze familial relationships in mothers and daughters in invasive and in situ cervical cancers from years 1958-1994, including a total of 125,000 in situ and 14,000 invasive cancers. In situ cancers were diagnosed on average 10 years earlier than invasive cancers. Familial relative risks (FRRs) were calculated separately for mothers and daughters, and were between 1.8 and 2.3 for the 2 forms. The risks were only slightly modified by age of onset, except at higher ages where there was no familial risk; in mothers, the risks increased if more than one daughter was affected. Aggregation of in situ cases among sisters was observed in families. Heritability estimates were between 0.11 and 0.15 for in situ and 0.22 and 0.34 for invasive cervical cancer. A comparison of cancers in mothers and daughters showed an association between cervical cancer and many cancer types observed in immunosuppressed patients, suggesting a role for a mild form of immunosuppression, in addition to sexual behavior leading to human-papilloma-virus infections, in familial cervical cancer.

Familial testicular cancer in a single-centre population

Familial occurrence of testicular cancer suggests a genetic predisposition to the disease. A genetic susceptibility may also be reflected by the occurrence of bilateral testicular neoplasms and the high rates of urogenital developmental anomalies in families prone to testicular cancer. In this study, the proportion of familial testicular cancer cases was analyzed retrospectively in a single-centre population of 693 testicular cancer patients treated between 1977 and 1997 and the relative risk (RR) for first-degree relatives of patients was estimated. In addition, the existence of bilateral testicular neoplasms and urogenital developmental anomalies in familial testicular cancer patients was evaluated. 24 of the 693 patients (3.5%) had a first-degree relative with testicular cancer. These 24 cases belonged to 17 families; in 7 of these 17 families both affected first-degree family members were part of the study population of 693 patients. Consequently, the 693 studied patients belonged to a total of 686 families. Thus, the actual proportion of familial testicular cancer was 2.5% (17 of 686 families). The familial cases consisted of 11 brother pairs, including 2 pairs of identical twins and 1 pair which also had two affected cousins, and 6 father-son pairs (in total 36 cases, 12 treated elsewhere). Estimates of the RR to first-degree relatives showed a 9- to 13-fold increased RR to brothers (P < 0.001) and a 2-fold increased RR to fathers (P = non-significant (n.s)) of testicular cancer patients. Among the 36 patients with familial testicular cancer, 2 (5.6%) had bilateral testicular cancer, 4 (11.1%) had undescended testis, 3 (8.3%) had inguinal hernia, and 1 (2.8%) showed renal hypoplasia. The present data on familial occurrence of testicular cancer may lend support to a role of genetic factors in the aetiology of testicular cancer.

Familial risk in head and neck squamous cell carcinoma diagnosed before the age of 45: a population-based study

This population-based study analyses familial risk as a factor in the development of head and neck squamous cell carcinoma before the age of 45. Two different designs were used: (1) estimation of standardised incidence ratios (SIRs) for cancer among first-degree relatives of 127 young head and neck cancer probands; and (2) estimation of odds ratios (ORs) for developing head and neck cancer associated with cancer in a first-degree relative. SIRs of cancer of the respiratory and upper digestive tract (lungs, oesophagus, and smoking-related head and neck sites [RUDT]) for first-degree relatives were 4.3 (95% confidence intervals or 95% CI of 1.6-9.5) for female patients, 1.0 (95% CI = 0.3-2.6) for male patients and 1.9 (95% CI = 0.9-3.5) for both sexes combined. ORs for head and neck cancer before the age of 45, in association with cancer of RUDT in a first-degree relative were 5.0 (95% CI = 1.4-17.3) for women, 1.1 (95% CI = 0.3-3.3) for men, and 2.0 (95% CI = 0.9-4.4) for both sexes combined. Hence, when analysing both sexes combined, our familial risk estimates for head and neck cancer showed non-significant increases. An explanation for the unexpected sex asymmetry in familial risk could be an interaction between inherent cancer susceptibility and a female biological characteristic. Alternatively, it could be artefacts caused by differences in familial smoking habits.

Familial cancers in a nationwide family cancer database: age distribution and prevalence

We calculated sex- and age-specific familial relative risks (FRRs) of cancer in offspring of cancer probands at 19 male and 20 female cancer sites, based on the nationwide Family Cancer Database from Sweden. The proportion of familial cancers among all cancers was also determined. The database contained 550,000 primary cancers. The familial risk at known sites: colon, breast, ovary, testis, skin (melanoma), nervous system, thyroid and other endocrine glands were confirmed. The FRR of thyroid cancer exceeded any other cancer and was over twice as high for male as for female offspring, and appeared to constitute an early- and late-onset component. Novel register-based findings were familial risks in cervical and uterine cancer, and in male offspring of male probands kidney and skin (mainly squamous cell) cancer. Familial risks were noted also for lung cancer, lymphoma and leukaemia but they may have largely environmental causes. The proportion of familial cancers depended on the site, ranging from 11% in prostate to 8.7% in female breast and to well below 1% at many sites.

Familial cancer risks in offspring from discordant parental cancers

Analysis of familial cancer risks between discordant sites provides etiologic understanding on genetic and environmental risks factors of site-specific cancers. We used the Swedish nation-wide Family-Cancer Database to analyze familial risks in discordant cancers of offspring and parents. Familial risk ratios (FRRs) were calculated for cancer in offspring aged 15 to 53 years at 22 sites, discordant from parental sites. We confirmed many reported associations. Consistent novel findings associated parental-offspring sites of pancreas-breast, breast-testis and uterus-nervous system. For these, the FRRs were modest, 1.2 to 1.5 in the whole Database, but the FRRs increased in those whose parents were diagnosed before age 50. Pancreas and liver cancers showed FRRs of 2.5 to 3.3 in offspring of women and of 1.3 in offspring of men. One or both of these cancers was/were associated with cancers of stomach, colon, breast, uterus, ovary and prostate. Melanoma was associated with pancreas, breast, skin and nervous-system cancers and with leukemias. Myeloma showed a concordant FRR of about 4.0 and was associated with prostate cancer and non-thyroid endocrine-gland cancers. Mutations in known cancer-related genes may explain some of these findings, but new susceptibility genes are yet to be found. For melanoma, pancreatic and liver cancer, environmental factors are important etiologic factors and may contribute to the familial effects observed.

Familial papillary thyroid carcinoma is genetically distinct from familial adenomatous polyposis coli

Familial papillary thyroid carcinoma (fPTC) is an inherited tumor syndrome characterized by isolated papillary thyroid carcinoma (PTC) in affected subjects. Its etiology is unknown. Large multigeneration families with PTC are very rare, and therefore, modern genetic linkage studies have not been applied extensively to this disorder. Familial adenomatous polyposis coli (FAP) is an inherited tumor syndrome enriched in PTC. FAP is caused by germline mutations of the adenomatous polyposis coli (APC) gene that is located in the 5q21 region. It is not known if fPTC is a phenotypic variant of FAP, or if it is a genetically distinct disorder. We report a large 3-generation fPTC kindred and use linkage analysis to test the hypothesis that fPTC and FAP are genetically distinct. In this kindred there are 25 living informative subjects; 5 have PTC, and 1 is an obligate carrier. Inheritance is autosomal dominant with incomplete penetrance. There is vertical transmission, multifocal disease, an average age of onset of 36 years, and 1 subject has colon cancer. The probability is approximately 1 in 2 billion against the clustering of 5 sporadic PTC cases in this kindred. To test for linkage to the APC gene we used 2 highly polymorphic markers, D5S656 and D5S421, which are located within a maximum distance of 1.7 megabase (Mb) of the APC gene and within an estimated genetic region of less than 1 centimorgan (cM) from each other. After polymerase chain reaction (PCR) amplification 18 family members were genotyped. Construction and inspection of haplotypes showed that the affected subjects do not share the same allelic composition. Using a penetrance ratio of 75%, linkage was excluded at 2 cM and 3 cM on both sides of D5S656 and D5S421, respectively. The combined haplotype of these 2 markers provided an exclusion region of 4 cM. We conclude that fPTC is genetically distinct from FAP.

Familial risks in second primary breast cancer based on a family cancer database

The nationwide Swedish Family Cancer Database was used to analyse the risk of breast cancer in daughters of mothers presenting second, bilateral breast cancer. The database contained information on family relationships and cancers of mothers and daughters when the daughter was born after 1940, totalling 55,411 maternal and 9966 daughters' primary breast cancers. Some 95% of the second breast cancers were diagnosed in the contralateral breast. Familial risk of breast cancer in daughters was 1.70 when the mothers had first breast cancer and 3.28 when the mothers had bilateral breast cancer. Thus, the increased familial effect of the second breast cancer was 1.93. The risk was highest in daughters diagnosed at a young age when the mother was diagnosed before 50 years of age. If the mothers had breast cancer following any other type of cancer, the familial effect was as for the first breast cancer (1.03). The age of onset for breast cancer in daughters was 0.7 years younger for those whose mother had bilateral as compared with unilateral breast cancer, although the difference was not statistically significant. The mothers with bilateral breast cancer whose daughters also had breast cancer were diagnosed with the first breast cancer 3.8 years younger than mothers whose daughters did not have breast cancer. The present results apply to a relatively young population of daughters (< 54 years of age).

Evidence for a rare prostate cancer-susceptibility locus at chromosome 1p36

Combining data from a genomic screen in 70 families with a high risk for prostate cancer (PC) with data from candidate-region mapping in these families and an additional 71 families, we have localized a potential hereditary PC-susceptibility locus to chromosome 1p36. Because an excess of cases of primary brain cancer (BC) have been observed in some studies of families with a high risk for PC, and because loss of heterozygosity at 1p36 is frequently observed in BC, we further evaluated 12 families with both a history of PC and a blood relative with primary BC. The overall LOD score in these 12 families was 3.22 at a recombination fraction (theta) of .06, with marker D1S507. On the basis of an a priori hypothesis, this group was stratified by age at diagnosis of PC. In the younger age group (mean age at diagnosis <66 years), a maximum two-point LOD score of 3.65 at straight theta = .0 was observed, with D1S407. This linkage was rejected in both early- and late-onset families without a history of BC (LOD scores -7.12 and -6.03, respectively, at straight theta = .0). After exclusion of 3 of the 12 families that had better evidence of linkage to previously described PC-susceptibility loci, linkage to the 1p36 region was suggested by a two-point LOD score of 4.74 at straight theta = .0, with marker D1S407. We conclude that a significant proportion of these families with both a high risk for PC and a family member with BC show linkage to the 1p36 region.

Familial and hereditary prostate cancer in southern Sweden. A population-based case-control study

The objectives of this study were to investigate the effect of family history on prostate cancer risk, to estimate the incidence of hereditary prostate cancer in southern Sweden and to assess the reliability of self-reported family history of prostate cancer. The study included consecutive prostate cancer patients and age-matched control subjects from a geographically defined population. The controls consisted of 1 male patient with malignant melanoma or non-Hodgkin's lymphoma and 1 male from the community per prostate cancer case. Family history was assessed with questionnaires, and diagnoses of fathers and brothers of cases were validated by the Southern Swedish Regional Tumour Registry. Among fathers and brothers whose names and birth dates were available, 56 (92%) of the 61 reported prostate cancer diagnoses were verified. Fifteen per cent of 356 cases and 5.0% of 712 controls reported at least 1 case of prostate cancer among their brothers or fathers, giving a relative risk of 3.2 (95% confidence interval 2.1-5.1). The relative risk increased with decreasing age at diagnosis of the patient. Based on the pedigree, 3.1% of the 356 patients were classified as having hereditary prostate cancer. This proportion was significantly higher among patients diagnosed before the age of 60 years (7.1%) than among older patients (2.2%). We conclude that there is a substantially increased risk of prostate cancer for sons and brothers of prostate cancer patients. The risk increases with decreasing age at diagnosis of the patient as an effect of a higher prevalence of hereditary prostate among early onset cases. Furthermore, we found self-reported family history of prostate cancer to be a valid estimate of the true incidence of prostate cancer in fathers and brothers of men with prostate cancer.

Cancer risk in close relatives of women with early-onset breast cancer--a population-based incidence study

Inherited susceptibility to breast cancer is associated with an early onset and bilateral disease. The extent of familial risks has not, however, been fully assessed in population-based incidence studies. The purpose of the study was to quantify the risks for cancers of the breast, ovary and other sites of close relatives of women in whom breast cancer was diagnosed at an early age. Records collected between 1943 and 1990 at the Danish Cancer Registry were searched, and 2860 women were found in whom breast cancer was diagnosed before age 40. Population registers and parish records were used to identify 14 973 parents, siblings and offspring of these women. Cancer occurrence through to 31 December 1993 was determined within the Cancer Registry's files and compared with national incidence rates. Women with early-onset breast cancer were at a nearly fourfold increased risk of developing a new cancer later in life (268 observed vs. 68.9 expected). The excess risk was most evident for second cancer of the breast (181 vs. 24.5) and for ovarian cancer (20 vs. 3.3). For mothers and sisters, risks for cancers of the breast and ovary were significantly increased by two- to threefold. Bilateral breast cancer and breast-ovarian cancer were very strong predictors of familial risks, with one in four female relatives predicted to develop breast and/or ovarian cancer by age 75. Mothers had a slightly increased risk of colon cancer, but not endometrial cancer. The risk for breast cancer was also increased among fathers (standardized incidence ratio 2.5; 95% CI 0.5-7.4) and especially brothers (29; 7.7-74), although based on small numbers. The risk for prostatic cancer was unremarkable. In this large population-based survey, the first-degree relatives of women who developed breast cancer before age 40 were prone to ovarian cancer as well as male and female breast cancer, but not other tumours that may share susceptibility genes with breast cancer.

Genetic epidemiology of prostate cancer

A family history of prostate cancer is a consistent risk factor for prostate cancer, and can also be used to predict the presence of prostate cancer among asymptomatic men who undergo PSA screening. Approximately 5% of cases of prostate cancer have a familial component. The genetic epidemiology of prostate cancer is complex, and genes on chromosome 1 and X chromosome contribute to familial aggregation. Neither of these prostate cancer susceptibility genes have been identified, but are the subject of an active search. Hereditary prostate cancer resembles non-hereditary cancer in terms of age of onset, pathologic appearance and grade.

Familial nonmedullary thyroid carcinoma

It is well-known that medullary thyroid carcinoma occurs in a familial form as part of the multiple endocrine neoplasia (MEN) 2 syndromes. However, it is less well-recognized that nonmedullary thyroid carcinoma (NMTC) sometimes is familial. Arising from the thyroid epithelial cell, the NMTCs include papillary, follicular, and anaplastic thyroid carcinoma. Although most NMTC are sporadic, there is increasing evidence for a familial form. When inherited, NMTC is autosomal dominant with partial penetrance, and it is not associated consistently with other malignancies. The average age of onset is about 38 years, and in some cases, it may be more aggressive than sporadic PTC; up to 5% of subjects with NMTC have a family history positive for the same disorder. The etiologic gene(s) have not been identified, although positional cloning of these genes may be possible. The evidence for and characteristics of familial NMTC will be reviewed, and the clinical and research implications will be discussed.

A gene predisposing to familial thyroid tumors with cell oxyphilia maps to chromosome 19p13.2

Familial nonmedullary thyroid cancer (FNMTC) is a clinical entity characterized by a phenotype more aggressive than that of its sporadic counterpart. Families with recurrence of nonmedullary thyroid cancer (NMTC) have been repeatedly reported in the literature, and epidemiological data show a very high relative risk for first-degree relatives of probands with thyroid cancer. The transmission of susceptibility to FNMTC is compatible with autosomal dominant inheritance with reduced penetrance, or with complex inheritance. Cases of benign thyroid disease are often found in FNMTC kindreds. We report both the identification of a new entity of FNMTC and the mapping of the responsible gene, named "TCO" (thyroid tumors with cell oxyphilia), in a French pedigree with multiple cases of multinodular goiter and NMTC. TCO was mapped to chromosome 19p13.2 by linkage analysis with a whole-genome panel of microsatellite markers. Interestingly, both the benign and malignant thyroid tumors in this family exhibit some extent of cell oxyphilia, which, until now, had not been described in the FNMTC. These findings suggest that the relatives of patients affected with sporadic NMTC with cell oxyphilia should be carefully investigated.

Acute promyelocytic leukaemia: epidemiology and risk factors. A report of the GIMEMA Italian archive of adult acute leukaemia. GIMEMA Cooperative Group

Acute promyelocytic leukaemia (APL) exhibits peculiar epidemiological, clinical, cytogenetic and molecular features, compared to the other acute myeloid leukaemias (AML). Data on epidemiology and occupational risk factors for APL desumed from the GIMEMA archive are reported and compared with those of the other AML. An exploratory case-case study was designed on AML patients from 56 haematology centres in Italy. Overall, 4296 patients older than 15 yr with a new diagnosis of acute leukaemia were recorded between July 1992 and July 1997. Of these, 335 were classified as APL, and 2894 as other AML. The median age of APL patients was 43 compared to 59 yr for the other AML (p < 0.00001). In order to identify peculiar risk factors for APL development, different parameters were compared in the 2 groups. After adjusting by age no significant differences were observed with regard to education, lifetime prevalence of cancer among siblings and previous diseases in the patient's history. Occupational exposure as a possible risk factor for APL showed no increased risk compared to other AML among farmers, builders and leather workers. A significant association was found in electricians (OR=4.4, 95% CI=2.0-9.7) and a weak association was found in wood workers (OR=3.2, 95% CI=0.8-10.8). The proportion of APL with respect to other AML was significantly higher in the north east of Italy compared to the rest of the country (OR=1.7, 95% CI=1.3-2.2). These data confirm the younger age of APL patients compared to the other AML. A possible role of electromagnetic fields is suggested by the higher risk of APL in electrical workers and in the more industrialized areas of the country.

Familial prostate cancer and possible associated malignancies: nation-wide register cohort study in Sweden

There is a familial aggregation of prostate cancer, and 5 to 10% of all prostate cancers are estimated to be inherited in an autosomal-dominant mode. A population-based cohort study was performed in order to study familial prostate cancer and associated malignancies. A nation-wide register cohort study was conducted using an unselected study population. The cohort of 5,595 sons and 5,089 daughters of Swedish men found to have prostate cancer between 1959 and 1963 was identified. All types of cancer reported between 1958 and 1992 in this cohort were identified through linkage to the Swedish Cancer Registry. The expected number of different cancers was calculated using incidence rates obtained from the Registry. A highly significant increased overall standardized incidence ratio (SIR) of 1.65 (95% CI, 1.49-1.83) was obtained for prostate cancer, with 370 observed cases compared with 224 expected prostate cancers. The SIR was 3.18 among cases 45 to 49 years old at diagnosis, with the risk gradually decreasing to a SIR of 1.45 among cases over 80 years of age. Among sons and daughters with a father whose prostate cancer was diagnosed at an early age (<70 years), an increased risk for colorectal cancer SIR 1.48 (1.10-1.95) was observed. No significant difference in cancer risk for other sites was observed among the daughters and sons of men with prostate cancer. This cohort study confirms earlier studies that a positive family history of prostate cancer is an important risk factor for developing this disease. Though increased risk was found for all ages, it was more pronounced in younger men. Since no other malignancy was significantly associated with prostate cancer, it is most likely that familial prostate cancer is "site-specific".

Age-specific familial risks in common cancers of the offspring

Quantitative data on familial cancer risks are important for clinical, psychological and scientific reasons. The available estimates carry many uncertainties due to sample size and possible bias in data collection and often refer to first-degree relatives of unspecified age and sex. We calculated sex- and age-specific familial hazard ratios (FHRs) of cancer in offspring aged 15-53 years of cancer probands at 16 male and 17 female cancer sites, based on registered nation-wide data, free from bias. The familial risks in offspring were high, > 5 for thyroid (FHR 10.7 in all offspring, CI 95% 6.9-16.6), and testicular cancer (FHR 5.4, CI 95% 2.6-11.3), or intermediate, FHR 2-5, for colon, rectal, lung, breast, cervical, uterine, ovarian, skin (melanoma and squamous cell) and other endocrine gland cancers. FHRs < 2.0 were observed for stomach, renal and nervous system cancers, lymphomas and leukemias. Some sex differences were observed: FHRs for male breast (only 2 cases) and thyroid cancers were over 2 times higher than the respective female ones. When parents were diagnosed before age 50 years, offspring were at an increased risk of familial breast, renal, skin (melanoma), nervous system, thyroid and non-thyroid endocrine gland cancers, particularly affecting young (< 40 years) individuals. The parental diagnostic age also affected offspring's risk of colon, rectal, uterine and ovarian cancers, but young individuals were not at a particular risk. No effect of age was noted for cervical cancer and lymphoma.

Immunohistochemical expression of BRCA2 protein and allelic loss at the BRCA2 locus in prostate cancer. CRC/BPG UK Familial Prostate Cancer Study Collaborators

Many epidemiological studies have reported an association between breast and prostate cancer. BRCA2 functions as a tumour-suppressor gene in about 35% of large familial breast-cancer clusters; its role in the pathogenesis of sporadic breast cancer is less clear. We have evaluated immunohistochemical expression of BRCA2 protein and allelic loss of markers at the BRCA2 locus in tissue derived both from sporadic and from familial cases of prostate cancer. Immunohistochemical analysis was performed in 167 paraffin-embedded archival specimens. Normal prostate and 75% (120/160) of prostate-cancer tissue did not express BRCA2 protein. However, 25% (40/160) of cancer cases did express patchy staining; of these, 17% (2711 60) expressed positive nuclear staining in normal glandular tissue adjacent to tumour (either in addition to, or, independent of tumour). Allelic loss is the hallmark of a tumour-suppressor gene. Markers flanking (D13S267, D13S260) and within (D13S171) the BRCA2 gene indicated allelic loss in at least one locus in 23% (17/73) of tumours analyzed. There was no difference in the rates of allelic loss between sporadic and familial tumours, nor was there any association between immunohistochemical staining and allelic loss. Although immunohistochemical staining provided no useful prognostic information, allelic loss at BRCA2 was shown in univariate analysis to be associated with poorer survival (log-rank test, p = 0.046).

Biological aggressiveness of hereditary prostate cancer: long-term evaluation following radical prostatectomy

PURPOSE

We answer the question of whether, following radical prostatectomy, prostate cancer in patients with a family history of prostate cancer relapses biochemically at the same rate as prostate cancer in appropriately matched patients with no family history.

MATERIALS AND METHODS

The study was performed in 2 parts. In both parts prostate specific antigen (PSA) progression was defined as a postoperative elevation in serum PSA greater than 0.2 ng./ml. Part 1 included 656 patients who underwent radical prostatectomy by the same surgeon. Men with a family history of prostate cancer in a father or brother (94) were compared to those with no history of prostate cancer in a father or brother (562). Part 2 comprised 52 men with a family history of prostate cancer consistent with hereditary prostate cancer (HPC). HPC is defined as a family with 3 generations affected, 3 first-degree relatives affected or 2 relatives affected before age 55 years. Each member of this HPC group was matched by postoperative Gleason score and postoperative pathological stage with a patient who also underwent radical prostatectomy in the same time frame by the same surgeon but who reported no family history of prostate cancer by telephone interview and questionnaire.

RESULTS

In part 1, 94 probands (14%) reported a history of prostate cancer in the father or in at least 1 brother. The remaining 562 probands (85%) reported no known history of prostate cancer in the father or brother(s). There was no statistically significant difference in the probability of maintaining an undetectable PSA between these 2 groups. In part 2, 45 of 52 pairs (87%) were matched identically for all matching criteria. Mean follow time for the sporadic and hereditary groups was 5.4 and 5.1 years, respectively. There was no statistically significant difference in the probability of maintaining an undetectable PSA between the 2 groups.

CONCLUSIONS

Men with an affected father or brother, or those with a family history consistent with HPC have the same outcome following radical prostatectomy as men with no family history of the disease. Combined with our previous studies, these findings suggest that there is no biologically important difference between hereditary and sporadic prostate cancers.

Familial breast cancer in the family-cancer database

We use the population-based Family-Cancer Database from Sweden to study familial breast cancer. The size of the population and the nation-wide registration of cancer offer unique possibilities for epidemiological studies of familial cancer, including complete and unbiased identification of cases in the probands and in their relatives, and complete and unbiased identification of the family relationships. Using the Database, we wanted to answer the following questions: (i) proportion of familial breast cancer among all breast cancers; (ii) familial relative risks in breast cancer alone or in combination with another cancer, defined either through the mother or the daughter; (iii) modification of familial risk by age; and (iv) effects of paternal breast cancer alone or in combination with maternal breast cancer. The proportion of familial female breast cancer among all breast cancers before 54 years of age in Sweden was 8.7%. The familial relative risk was about 1.8, but is likely to decrease to about 1.5 in the ageing population. The higher familial relative risks were evident in young women, being 4.0 when both the mothers and their daughters were diagnosed at ages <40 years. Paternal breast cancer, in combination with maternal breast cancer, caused a large (but not statistically significant) risk in the daughters. In mothers and daughters, ovarian but not colon cancer was increased in combination with breast cancer.

Evidence for autosomal dominant inheritance of prostate cancer

A family-history cancer survey was conducted on 5,486 men who underwent a radical prostatectomy, for clinically localized prostate cancer, in the Department of Urology at the Mayo Clinic during 1966-95; 4,288 men responded to the survey. Complex segregation analysis was performed to assess the genetic basis of age at diagnosis and the familial clustering of prostate cancer. For the total group, no single-gene model of inheritance clearly explained familial clustering of disease, which could be partly explained by lack of Hardy-Weinberg equilibrium, with an excess of homozygotes. After accounting for deviations from Hardy-Weinberg equilibrium, the best-fitting model that explained the familial aggregation and age at diagnosis was a rare autosomal dominant susceptibility gene, and this model fitted best when probands were diagnosed at <60 years of age. The model predicts that the frequency of the susceptibility gene in the population is .006 and that the risk of prostate cancer by age 85 years is 89% among carriers of the gene and 3% among noncarriers. A strength of our study is its large size, such that genetic models could be fitted within strata defined by the age of the proband. Although the autosomal dominant model was consistently the best model, the parameter estimates differed somewhat (P=.03) across the different age groups, suggesting genetic heterogeneity. Additional evidence that the hereditary basis of prostate cancer is likely to be genetically complex was provided by the following: (1) there was a significantly elevated age-adjusted risk of prostate cancer among brothers of probands, compared with their fathers (relative risk 1.5 [95% confidence interval 1.4-1.7]); (2) the autosomal dominant model predicted an excess of homozygotes, over that predicted by Hardy-Weinberg equilibrium; and (3) the model-predicted risk of prostate cancer among relatives was inadequate when probands were diagnosed at age >=70 years.