Xinjun Li

The nation-wide Swedish family-cancer database updated structure and familial rates

The Swedish Family-Cancer Database was expanded to include all Swedes born in 1932 and later (offspring) with their parents, totaling 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry from the years 1958 to 1998, including over 1 million primary cancers and in situ tumors. Some 10% of offspring diagnosed with cancer lack any parental information. Incidence rates of cancers were similar in the database and in the Cancer Registry to age 70, but at higher ages the rates in the Database were lower, probably because of selection. The familial risk for all types of cancer in offspring was 1.73 when a parent had the same type of cancer. The familial rates were increased for all main cancer sites, except for the upper aerodigestive tract, stomach, liver, pancreas and bone marrow (leukemia). The rates were 7.47 for thyroid, 4.69 for testis, and over 2.00 for melanoma, ovary, prostate, skin, endocrine glands and endometrium.The Swedish Family-Cancer Database was expanded to include all Swedes born in 1932 and later (offspring) with their parents, totaling 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry from the years 1958 to 1998, including over 1 million primary cancers and in situ tumors. Some 10%, of offspring diagnosed with cancer lack any parental information. Incidence rates of cancers were similar in the database and in the Cancer Registry to age 70, but at higher ages the rates in the Database were lower, probably because of selection. The familial risk for all types of cancer in offspring was 1.73 when a parent had the same type of cancer. The familial rates were increased for all main cancer sites, except for the upper aerodigestive tract, stomach, liver, pancreas and bone marrow (leukemia). The rates were 7.47 for thyroid, 4.69 for testis, and over 2.00 for melanoma, ovary, prostate, skin, endocrine glands and endometrium.

Incidence trends and risk factors of carcinoid tumors

Carcinoids are rare indolent neuroendocrine tumors, mainly located in bowel, stomach, and lung. Their etiology is virtually unknown although a family history is a minor cause.

Familial aggregation of Hodgkin lymphoma and related tumors

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.

Cancer risks in first-generation immigrants to Sweden

We used the nationwide Swedish Family‐Cancer Database to analyse cancer risks in 613,000 adult immigrants to Sweden. All the immigrants had become parents in Sweden and their median age at immigration was 24 years for men and 22 years for women. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for 18 cancer sites using native Swedes as a reference. Data were also available from compatriot marriages. All cancer was decreased by 5% and 8% for immigrant men and women, respectively. However, most of the male increase was due to lung cancer for which male immigrants showed a 41% excess. Among individual cancer sites and immigrant countries, 110 comparisons were significant, 62 showing protection and 48 an increased risk. Most of the differences between the rates in immigrants and Swedes could be ascribed to the variation of cancer incidence in the indigenous populations. Some high immigrant SIRs were 5.05 (n = 6, 95% CI 1.82–11.06) for stomach cancer in Rumanian women and 2.41 (41, 1.73–3.27) for lung cancer in Dutch men. At some sites, such as testis, prostate, skin (melanoma), kidney, cervix and nervous system, the SIRs for immigrants were decreased; in some groups of immigrants SIRs were about 0.20. The highest rates for testicular cancer were noted for Danes and Chileans. Women from Yugoslavia and Turkey had an excess of thyroid tumours. All immigrant groups showed breast, endometrial and ovarian cancers at or below the Swedish level but the differences were no more than 2‐fold.

Familial associations of rheumatoid arthritis with autoimmune diseases and related conditions

OBJECTIVE In the era of genome-wide association studies, familial risks are used to estimate disease heritability and the likelihood of candidate-gene identification. This study was undertaken to estimate associations of rheumatoid arthritis (RA) with any of 33 autoimmune diseases and related conditions among parents and offspring, singleton siblings, twins, and spouses. METHODS The Multigeneration Register in Sweden was used as a reliable source of information on Swedish families throughout the last century. Data on autoimmune diseases in individual family members were obtained through linkage to the Hospital Discharge Register. The standardized incidence ratio (SIR) was calculated as a measure of the relative risk of RA in family members of patients with RA or any of 33 other autoimmune diseases or related conditions, as compared with the relative risk of RA in those lacking an affected family member. RESULTS Among a total of 447,704 patients, 47,361 were diagnosed as having RA. The SIRs for RA were 3.02 in offspring of affected parents, 4.64 in siblings, 9.31 in multiplex families, 6.48 in twins, and 1.17 in spouses. Significant associations with the familial risk of RA in offspring according to parental proband were observed for ankylosing spondylitis (SIR 2.96), localized scleroderma (SIR 2.40), Sjögrens syndrome (SIR 2.25), systemic lupus erythematosus (SIR 2.13), systemic sclerosis (SIR 1.65), Hashimoto thyroiditis/hypothyroidism (SIR 1.54), pernicious anemia (SIR 1.53), sarcoidosis (SIR 1.40), psoriasis (SIR 1.36), Wegeners granulomatosis (SIR 1.34), and asthma or polymyalgia rheumatica (SIR 1.32). CONCLUSION This is the first study to compare the familial risks of RA in relation to a large number of autoimmune diseases and related conditions using data from a single population. The high discordant familial risks in this population suggest that there is extensive genetic sharing between RA and the associated diseases.

Cancer risks in second-generation immigrants to Sweden

We used the nationwide Swedish Family‐Cancer Database to analyze cancer risks in Sweden‐born descendants of immigrants from European and North American countries. Our study included close to 600,000 0–66‐year‐old descendants of an immigrant father or mother. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for 17 cancer sites using native Swedes as a reference. All cancer was marginally below the Swedish incidence in offspring of immigrant origin. Decreased SIRs were observed for breast cancer among Norwegian descendants, melanoma among descendants of Hungarian fathers and ovarian and bladder cancer among descendents of Finnish mothers, all consistent with the difference in cancer incidence between Swedes and the indigenous populations. Cervical cancer was increased in daughters of Danish men, whereas thyroid cancer and non‐Hodgkins lymphoma were in excess in offspring of parents of Yugoslav and Asian descent. Even these results agreed with the high incidence rates in parents compared to Swedes, except that for non‐Hodgkins lymphoma other explanations are needed; these may be related to immune malfunction. Comparison of the results between the first‐ and the second‐generation immigrants suggest that the first 2 decades of life are important in setting the pattern for cancer development in subsequent life. Birth in Sweden sets the Swedish pattern for cancer incidence, irrespective of the nationality of descent, while entering Sweden in the 20s is already too late to influence the environmentally imprinted program for the cancer destiny.

Familial carcinoid tumors and subsequent cancers : a nation-wide epidemiologic study from Sweden

Carcinoids are rare neuroendocrine tumors, mainly located in the bowel, stomach and lung. Familial risks in carcinoid tumours are not well known apart from multiple endocrine neoplasia 1 (MEN1). We used the nation‐wide Swedish Family‐Cancer Database on 10.1 million individuals for assessment. Carcinoid tumors were retrieved from the Cancer Registry covering the years 1958–1998. The offspring generation, aged 0–66 years, accumulated 190 million person‐years at risk. The age‐adjusted incidence rates were 0.76 for men and 1.29/100,000 for women. Standardized incidence ratios (SIRs) were calculated for offspring when their parents had a carcinoid or any other cancer. When parents presented with carcinoids, SIRs for offspring were 4.35 (n = 8, 95% CI 1.86–7.89) for small intestinal and 4.65 (n = 4, 95% CI 1.21–10.32) for colon carcinoids. If both offspring and parents presented with small intestinal carcinoids, the SIR was 12.31 (n = 4, 95% CI 3.20–27.34). Offspring carcinoids were also increased if parents presented with bladder and endocrine gland tumors, the latter association probably partially due to MEN1. Risks for second cancers were increased, particularly at sites where familial risks were found, including carcinoids in the small intestine.

Familial and second primary pancreatic cancers: a nationwide epidemiologic study from Sweden.

Familial risk of pancreatic cancer has been mainly assessed through case‐control studies based on reported but not medically verified cancers in family members. We used the nationwide Swedish Family‐Cancer Database on 10.2 million individuals and 21,000 pancreatic cancers to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for pancreatic cancer in 0‐ to 66‐year‐old offspring of parents with pancreatic or other specified tumors. Additionally, SIRs for second primary pancreatic cancers were analyzed after any first neoplasm. SIRs for pancreatic cancer (1.68, 95% CI 1.16–2.35) and pancreatic adenocarcinoma (1.73, 95% CI 1.13–2.54) were increased when a parent presented with pancreatic cancer. The risk was not dependent on diagnostic age of offspring or parents. Pancreatic cancer was associated with parental lung, rectal or endometrial cancer and with melanoma. SIRs for pancreatic cancer were 10.01 and 7.96 among offspring who were diagnosed before age 50 years when parents were diagnosed with squamous cell and adenocarcinoma of the lung, respectively, before age 60 years. The population‐attributable proportion of familial pancreatic cancer was 1.1%. Risks for second pancreatic cancers were increased in men and women after small intestinal, colon and bladder cancer. The degree of familial clustering for pancreatic cancer and its population‐attributable proportion were lower than the data cited in the literature. Clustering of pancreatic cancer with sites presenting in hereditary nonpolyposis colorectal cancer was noted. The strong association of pancreatic and lung cancers is puzzling, and it remains unclear to what extent this represents familial sharing of smoking habits.

Familial risk of cancer: Data for clinical counseling and cancer genetics

Familial risks for cancer are important for clinical counseling and understanding cancer etiology. Medically verified data on familial risks have not been available for all types of cancer. The nationwide Swedish Family‐Cancer Database includes all Swedes born in 1932 and later (0–to 68‐year‐old offspring) with their parents, totaling over 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry up to year 2000. Standardized incidence ratios (SIR) and 95% confidence limits (CI) were calculated for age‐specific familial risk in offspring by an exact proband status. The familial risks for offspring cancer were increased at 24/25 sites from concordant cancer in only the parent, at 20/21 sites from a sibling proband and at 12/12 sites from a parent and sibling proband. The highest SIRs by parent were for Hodgkins disease (4.88) and testicular (4.26), non‐medullary thyroid (3.26), ovarian (3.15) and esophageal (3.14) cancer and for multiple myeloma (3.33). When a sibling was affected, even prostate, renal, squamous cell skin, endocrine, gastric and lung cancer and leukemia showed SIRs in excess of 3.00. The highest cumulative risks were found for familial breast (5.5%) and prostate (4.2%) cancers. We identified reliable familial risks for 24 common neoplasms, most of which lack guidelines for clinical counseling or action level. If, for example, a familial SIR of 2.2 would be use as an action level, counseling would be needed for most cancers at some diagnostic age groups. The present data provide the basis for clinical counseling.

Age- and Gender-Specific Familial Risks for Venous Thromboembolism A Nationwide Epidemiological Study Based on Hospitalizations in Sweden

Background— This nationwide study sought to determine age- and gender-specific familial risks in siblings hospitalized for venous thromboembolism (VTE). Methods and Results— The Swedish Multigeneration Register on 0- to 75-year-old subjects was linked to the Hospital Discharge Register for the years 1987–2007. Standardized incidence ratios were calculated for individuals whose siblings were hospitalized for VTE compared with those whose siblings were not affected. Among a total of 45 362 hospitalized cases with VTE, 2393 affected siblings were identified, with a familial standardized incidence ratio of 2.45 (95% confidence interval [CI], 1.66 to 3.61). Gender-specific differences in incidence rates were observed. The familial risks were significantly increased from the age of 10 to 69 years, with a familial standardized incidence ratio of 4.77 (95% CI, 1.96 to 10.83) at ages 10 to 19 years, which decreased to 2.08 (95% CI, 1.35 to 3.20) at ages 60 to 69 years, although the absolute risk increased with age. The familial standardized incidence ratios for siblings with 2 and ≥3 affected probands were 51.87 (95% CI, 31.47 to 85.00) and 53.69 (95% CI, 25.59 to 108.50), respectively. Spouses had low familial risks (standardized incidence ratio=1.07; 95% CI, 1.04 to 1.10; observed spouse cases=3900). Conclusions— Familial factors, although influenced by age and gender, are important risk factors for VTE. The present study shows that VTE is aggregated in families and suggests that uncovering the sources of familial aggregation (genetic and nongenetic) may be worthwhile. Moreover, in a small fraction of siblings, the familial risk was very high, suggesting segregation of rare but strong genetic risk factors.Background— This nationwide study sought to determine age- and gender-specific familial risks in siblings hospitalized for venous thromboembolism (VTE). Methods and Results— The Swedish Multigeneration Register on 0- to 75-year-old subjects was linked to the Hospital Discharge Register for the years 1987–2007. Standardized incidence ratios were calculated for individuals whose siblings were hospitalized for VTE compared with those whose siblings were not affected. Among a total of 45 362 hospitalized cases with VTE, 2393 affected siblings were identified, with a familial standardized incidence ratio of 2.45 (95% confidence interval [CI], 1.66 to 3.61). Gender-specific differences in incidence rates were observed. The familial risks were significantly increased from the age of 10 to 69 years, with a familial standardized incidence ratio of 4.77 (95% CI, 1.96 to 10.83) at ages 10 to 19 years, which decreased to 2.08 (95% CI, 1.35 to 3.20) at ages 60 to 69 years, although the absolute risk increased with age. The familial standardized incidence ratios for siblings with 2 and ≥3 affected probands were 51.87 (95% CI, 31.47 to 85.00) and 53.69 (95% CI, 25.59 to 108.50), respectively. Spouses had low familial risks (standardized incidence ratio=1.07; 95% CI, 1.04 to 1.10; observed spouse cases=3900). Conclusions— Familial factors, although influenced by age and gender, are important risk factors for VTE. The present study shows that VTE is aggregated in families and suggests that uncovering the sources of familial aggregation (genetic and nongenetic) may be worthwhile. Moreover, in a small fraction of siblings, the familial risk was very high, suggesting segregation of rare but strong genetic risk factors. # Clinical Perspective {#article-title-47}