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

Risk-adapted starting age of breast cancer screening in women with a family history of ovarian or other cancers: A nationwide cohort study

BACKGROUND

There is a lack of evidence-based recommendations for the age at which women with a family history of cancers other than breast cancer should start breast cancer screening.

METHODS

Using Swedish family cancer data sets, the authors conducted a nationwide cohort study including 5,099,172 Swedish women born after 1931 (follow-up, 1958-2015). Accounting for calendar time, they calculated the relative risk of breast cancer for women with a family history of a discordant cancer in 1 first-degree relative. Furthermore, the authors used 10-year cumulative risk to determine the ages at which women with a family history of discordant cancer reached risk thresholds at which women in the general population were recommended to start breast cancer screening.

RESULTS

A family history of cancer at 15 sites was associated with an increased risk of breast cancer. Among women younger than 50 years, the highest risk of breast cancer was observed for those with a family history of ovarian cancer (standardized incidence ratio, 1.44; 95% confidence interval, 1.26-1.64). In these women, the risk of breast cancer associated with a family history at other cancer sites ranged from 1.08-fold for prostate cancer to 1.18-fold for liver cancer. When breast cancer screening was recommended to be started at the age of 50 years for the general population, women with 1 first-degree relative with ovarian cancer attained the threshold risk for screening at the age of 46 years. Women with a family history of other discordant cancers did not reach the risk thresholds for screening at younger ages.

CONCLUSIONS

Many cancers showed familial associations with breast cancer, but women with a family history of these cancers (except for ovarian cancer) did not reach risk thresholds for screening at younger ages.

Risk-Adapted Starting Age of Screening for Relatives of Patients With Breast Cancer

Importance

Breast cancer screening guidelines acknowledge the need for earlier screening for women at increased risk but provide limited guidance for women with a family history of breast cancer. A risk-adapted starting age of screening for relatives of patients with breast cancer may help supplement current screening guidelines.

Objective

To identify the risk-adapted starting age of breast cancer screening on the basis of a woman's detailed family history.

Design, Setting, and Participants

This nationwide cohort study analyzed data recorded in the Swedish family-cancer data sets. All women born from 1932 onward and with at least 1 known first-degree relative (FDR) were included (N = 5 099 172). Data from January 1, 1958, to December 31, 2015, were collected. Data were analyzed from October 1, 2017, to March 31, 2019.

Exposures

Family history of breast cancer in FDRs and second-degree relatives (SDRs).

Main Outcomes and Measures

Primary invasive breast cancer diagnosis and the age at which women with different constellations of family history attained the risk level at which breast screening is usually recommended.

Results

Of the 5 099 172 women included in the study, 118 953 (2.3%) received a diagnosis of primary invasive breast cancer. A total of 102 751 women (86.4%; mean [SD] age at diagnosis, 55.9 [11.1] years) did not have family history of breast cancer in FDRs and SDRs at the time of their diagnosis. Risk-adapted starting age of breast cancer screening varied by number of FDRs and SDRs with breast cancer diagnosis and the age at diagnosis of the FDRs. For example, for screening recommendation at age 50 years for the general population (2.2% 10-year cumulative risk), women with multiple affected FDRs, with the youngest affected relative receiving a diagnosis before age 50 years, reached the benchmark risk level at age 27 years. When the youngest relative received a diagnosis after age 50 years, however, this risk level was attained at age 36 years.

Conclusions and Relevance

This study identifies possible risk-based starting ages for breast cancer screening based on population-based registers. These results may serve as high-quality evidence to supplement current screening guidelines for relatives of patients with breast cancer.

Analysis of 153 115 patients with hematological malignancies refines the spectrum of familial risk

Estimating familial cancer risks is clinically important in being able to discriminate between individuals in the population at differing risk for malignancy. To gain insight into the familial risk for the different hematological malignancies and their possible inter-relationship, we analyzed data on more than 16 million individuals from the Swedish Family-Cancer Database. After identifying 153 115 patients diagnosed with a primary hematological malignancy, we quantified familial relative risks (FRRs) by calculating standardized incident ratios (SIRs) in 391 131 of their first-degree relatives. The majority of hematological malignancies showed increased FRRs for the same tumor type, with the highest FRRs being observed for mixed cellularity Hodgkin lymphoma (SIR, 16.7), lymphoplasmacytic lymphoma (SIR, 15.8), and mantle cell lymphoma (SIR, 13.3). There was evidence for pleiotropic relationships; notably, chronic lymphocytic leukemia was associated with an elevated familial risk for other B-cell tumors and myeloproliferative neoplasms. Collectively, these data provide evidence for shared etiological factors for many hematological malignancies and provide information for identifying individuals at increased risk, as well as informing future gene discovery initiatives.

Family history and the natural history of colorectal cancer: systematic review

PURPOSE

Family history of colorectal cancer (CRC) is a known risk factor for CRC and encompasses both genetic and shared environmental risks.

METHODS

We conducted a systematic review to estimate the impact of family history on the natural history of CRC and adherence to screening.

RESULTS

We found high heterogeneity in family-history definitions, the most common definition being one or more first-degree relatives. The prevalence of family history may be lower than the commonly cited 10%, and confirms evidence for increasing levels of risk associated with increasing family-history burden. There is evidence for higher prevalence of adenomas and of multiple adenomas in people with family history of CRC but no evidence for differential adenoma location or adenoma progression by family history. Limited data regarding the natural history of CRC by family history suggest a differential age or stage at cancer diagnosis and mixed evidence with respect to tumor location. Adherence to recommended colonoscopy screening was higher in people with a family history of CRC.

CONCLUSION

Stratification based on polygenic and/or multifactorial risk assessment may mature to the point of displacing family history-based approaches, but for the foreseeable future, family history may remain a valuable clinical tool for identifying individuals at increased risk for CRC.

Mutator/Hypermutable fetal/juvenile metakaryotic stem cells and human colorectal carcinogenesis

Adult age-specific colorectal cancer incidence rates increase exponentially from maturity, reach a maximum, then decline in extreme old age. Armitage and Doll (1) postulated that the exponential increase resulted from "n" mutations occurring throughout adult life in normal "cells at risk" that initiated the growth of a preneoplastic colony in which subsequent "m" mutations promoted one of the preneoplastic "cells at risk" to form a lethal neoplasia. We have reported cytologic evidence that these "cells at risk" are fetal/juvenile organogenic, then preneoplastic metakaryotic stem cells. Metakaryotic cells display stem-like behaviors of both symmetric and asymmetric nuclear divisions and peculiarities such as bell shaped nuclei and amitotic nuclear fission that distinguish them from embryonic, eukaryotic stem cells. Analyses of mutant colony sizes and numbers in adult lung epithelia supported the inferences that the metakaryotic organogenic stem cells are constitutively mutator/hypermutable and that their contributions to cancer initiation are limited to the fetal/juvenile period. We have amended the two-stage model of Armitage and Doll and incorporated these several inferences in a computer program CancerFit v.5.0. We compared the expectations of the amended model to adult (15-104 years) age-specific colon cancer rates for European-American males born 1890-99 and observed remarkable concordance. When estimates of normal colonic fetal/juvenile APC and OAT gene mutation rates (∼2-5 × 10(-5) per stem cell doubling) and preneoplastic colonic gene loss rates (∼8 × 10(-3)) were applied, the model was in accordance only for the values of n = 2 and m = 4 or 5.

Familial risk of early and late onset cancer: nationwide prospective cohort study

OBJECTIVE

To determine whether familial risk of cancer is limited to early onset cases.

DESIGN

Nationwide prospective cohort study.

SETTING

Nationwide Swedish Family-Cancer Database.

PARTICIPANTS

All Swedes born after 1931 and their biological parents, totalling >12.2 million individuals, including >1.1 million cases of first primary cancer.

MAIN OUTCOME MEASURES

Familial risks of the concordant cancers by age at diagnosis.

RESULTS

The highest familial risk was seen for offspring whose parents were diagnosed at an early age. Familial risks were significantly increased for colorectal, lung, breast, prostate, and urinary bladder cancer and melanoma, skin squamous cell carcinoma, and non-Hodgkin's lymphoma, even when parents were diagnosed at age 70-79 or 80-89. When parents were diagnosed at more advanced ages (≥ 90), the risk of concordant cancer in offspring was still significantly increased for skin squamous cell carcinoma (hazard ratio 1.9, 95% confidence interval 1.4 to 2.7), colorectal (1.6, 1.2 to 2.0), breast (1.3, 1.0 to 1.6), and prostate cancer (1.3, 1.1 to 1.6). For offspring with a cancer diagnosed at ages 60-76 whose parents were affected at age <50, familial risks were not significantly increased for nearly all cancers.

CONCLUSION

Though the highest familial risks of cancer are seen in offspring whose parents received a diagnosis of a concordant cancer at earlier ages, increased risks exist even in cancers of advanced ages. Familial cancers might not be early onset in people whose family members were affected at older ages and so familial cancers might have distinct early and late onset components.

The Swedish Family-Cancer Database 2009: prospects for histology-specific and immigrant studies

The Swedish Family-Cancer Database comprises a total of 11.8 million individuals covering the Swedish population of the past 100 years. Version VIII of the Database is described in the present article. Cancer cases were retrieved from the Swedish Cancer Registry for the period 1958-2006, including more than 1 million first primary cancers. The number of familial cancers in offspring is 14,000 when a parent was diagnosed with a concordant (same) cancer and the number of concordant siblings was 6,000. From the year 1993 onwards histopathological data according to the SNOMED classification were used, which entails advantages for certain cancers, such as breast cancer. Even though the specific morphological classification only covers a limited number of years, it does cover most familial cancers in the offspring generation. The Database records the country of birth for each subject. A total of 1.79 million individuals were foreign born, Finns and other Scandinavians being the largest immigrant groups. The cancer incidence in the first-generation immigrants was compared to that in native Swedes using standardised incidence ratios (SIRs) to measure relative risk. The SIRs ranged widely between the immigrant groups, from 1.9-fold for myeloma to 25-fold for melanoma. The differences in SIRs were smaller in the second-generation immigrants. The usefulness and the possible applications of the Family-Cancer Database have increased with increasing numbers of cases, and the numerous applications have been described in some 300 publications. Familial cancer studies are in the stimulating interphase of the flourishing disciplines of genetics and epidemiology.

Inheritance of Colorectal Cancer

Inheritance is involved in up to one third of colon cancer cases. Highly penetrant inherited syndromes account for approximately 3%, while more common, but less penetrant inherited factors play a role in the remainder. Approaches to recognizing each of these categories and syndromes, using genetic testing for diagnosis where indicated, and accomplishing proper cancer screening and surveillance will be outlined in this review.

Familial risks for asthma among twins and other siblings based on hospitalizations in Sweden

BACKGROUND

Asthma is a common disabling condition, with known environmental and familial risk factors and with their assumed interactions. We wanted to carry out a family study on asthma to address gene-environment interactions at a population level.

METHODS

We conducted a nation-wide study on familial risks for asthma. An asthma database was constructed by linking the Multigeneration Register on 0-72-year-old subjects to the Hospital Discharge Register for diagnosed asthma cases in Sweden from years 1987 to 2004. Standardized incidence ratios (SIRs) were calculated for affected singleton siblings, twins and spouses by comparing with those whose siblings or spouses had no asthma.

RESULTS

A total of 67 370 hospitalized cases and 5638 affected siblings were identified with a familial SIR of 3.70, which was independent of sex, diagnostic age and age differences between the siblings. The SIR for different-sex twins was 5.17 and for same-sex twins it was 13.38. There was a low correlation between spouses for asthma.

CONCLUSIONS

Asthma shows a higher familial risk than many common diseases. The higher difference in familial excess risk between singleton siblings and different-sex twins provides strong genetic epidemiological evidence for gene-environment interactions in asthma. The concept of gene-environment interactions needs to be accommodated in future aetiological studies on asthma. Data on environmental factors and family history are important for clinical risk estimation.

Familial blood vessel tumors and subsequent cancers

BACKGROUND

Population-based data on the familial risk for vascular tumors are largely lacking. Such data are important for clinical counseling and cancer genetics.

METHODS

We used the Swedish Family-Cancer Database to calculate standardized incidence ratios for specific subtypes of vascular tumors in offspring using parents as probands. In addition, risks for second cancers were analyzed.

RESULTS

Offspring hemangioblastoma in the nervous system was associated with parental kidney cancer and nervous system hemangioblastoma and hemangioma. Offspring nervous system hemangiopericytoma was associated with parental pituitary adenomas. Offspring angiosarcoma in the trunk and extremities was associated with maternal breast cancer. Second Kaposi's sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease and myeloma were increased following primary skin Kaposi's sarcoma. Kidney and endocrine gland tumors and nervous system hemangioblastomas and hemangiomas were in excess following primary nervous system hemangioblastoma and hemangioma.

CONCLUSIONS

Our data showed that familial clustering of nervous system hemangioblastoma and hemangioma and the risks of subsequent cancers were primarily related to von-Hippel-Lindau disease. As a novel association, offspring nervous system hemangiopericytomas were in excess when parents were diagnosed with pituitary adenoma. Similarly, offspring angiosarcoma is associated with maternal breast cancer. Immunodeficiency may explain the excess of lymphoproliferative diseases after skin Kaposi's sarcoma.

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

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

Lifestyle and cancer: effect of parental divorce

According to previous studies, divorced individuals have increased risks of cancers related to alcohol and tobacco consumption and sexual habits, but the increases are balanced with decreased risks of many common cancers. In the present study, cancer risks were analyzed for 0-70-year-old offspring of divorced parents, on the basis the Swedish Family-Cancer Database with cancer data from the years 1958 to 2002. We calculated standardized incidence ratios for cancer among offspring of divorced parents (19,000 cancer patients) and compared them with offspring of stably married parents (121,000 cancer patients). Standardized incidence ratios were adjusted for many factors, including socio-economic status. Offspring of divorced parents were divided into groups depending on whether their mothers, fathers or both had had children with different partners. Offspring of divorced parents had an increased risk of upper aerodigestive tract, esophageal, anal, pancreatic, lung and cervical cancers. Decreased risks were noted for Hodgkin's disease and bone cancer. For Hodgkin's disease, the data suggest protective effects through early exposure to childhood pathogens but for bone cancer mechanisms remain to be established. The overall cancer risk for offspring of divorced parents was at or above unity. The results show that offspring of divorced parents have increased cancer risks at tobacco-related, alcohol-related and sex-related sites, in analogy to their parent, but they lack decreased risks at common sites, experienced by their parents. Divorce is becoming increasingly common in many countries and any deviant cancer patterns among offspring of divorced parents will have an impact on the population risk.

Familial risk for histology-specific bone cancers: an updated study in Sweden

We used the nation-wide Swedish Family-Cancer Database to examine the familial risks of histology-specific bone cancers in offspring by parental or sibling probands. Adjusted standardised incidence ratios (SIRs) were used to measure the risk. Among the 1327 offspring bone cancers, only two parent-offspring pairs and one sibling pair were noted with concordant bone cancer but the SIRs were not significant. Significant associations were observed in specific histological types or specific age groups, some of which may be chance findings arising from multiple comparisons. However, the risk of early-onset (< 25 years) osteosarcoma in offspring was significantly increased when mothers presented with breast cancer (1.7) and melanoma (2.9), suggesting that Li-Fraumeni syndrome could partly explain this familial aggregation. Other associations, such as childhood osteosarcoma with parental liver cancer, Ewing's sarcoma with kidney cancer and giant cell sarcoma with maternal breast cancer, were novel findings and may be related to other familial diseases.

Incidence of multiple primary malignancies among patients with bone cancers in Sweden

PURPOSE

The present study aimed at quantifying risks for second malignancies in patients with bone cancers, and risks for second bone cancers after other primary tumors.

METHODS

Adjusted standardized incidence ratios (SIRs) were used as a measure of risk.

RESULTS

Among 2,546 primary bone cancer patients, a total of 171-second malignancies occurred. Besides second bone cancers, other cancer sites with an increased SIR were the soft tissues and endocrine glands. The overall risk of second malignancies following Ewing's sarcoma was 5.63, followed by chordoma (1.99), osteosarcoma (1.54), and chondrosarcoma (1.51). Patients diagnosed before age 20 years showed an increased SIR of 3.11. The increased occurrence of second bone cancers was noted after the cancer sites of upper aerodigestive tract, kidney and nervous system.

CONCLUSIONS

The incidence of second primary malignancies in bone cancer patients was moderately increased. Among histological types, Ewing's sarcoma showed the highest risk of developing second cancers. Young age was also associated with an increased risk. Besides therapeutic effects, the observed excesses of a second bone or soft tissue tumor may be related to Li-Fraumeni syndrome. Increases at other sites may be related to unknown factors or spurious findings.

Second primary malignancies among patients with soft tissue tumors in Sweden

Survival from soft tissue tumors (STTs) has been improved because of the successful treatment. One of the late sequelae in STT survivors is the development of a second malignancy. The present study aimed at quantifying risks for second malignancies in patients with STTs, and risks for second STTs after other primary malignancies. Adjusted standardized incidence ratios (SIRs), calculated from the Swedish Family-Cancer Database, were used as a measure of risk. Among 6,671 primary STT patients, a total of 650 second malignancies occurred. Besides second STTs, other cancer sites with an increased SIR were the nervous system, endocrine glands, skin (melanoma and squamous cell carcinoma) and prostate; the risk for non-Hodgkin lymphoma (NHL) was also increased. The overall risk of second malignancies decreased in the following order: fibrosarocma (1.63) > myxosarcoma (1.48) > leiomyosarcoma (1.44) > liposarcoma (1.21). An increased risk of second STTs after primary cancers of the bone, ovary, nervous system, cervix, thyroid gland, skin, endometrium, breast, upper aerodigestive tract, and after Hodgkin disease, NHL and leukemia was also noted. This study showed that the incidence of second primary malignancies in patients with STTs was increased, but the SIRs varied among specific cancer sites. Besides therapeutic effects, the associations between STTs and bone and nervous system tumors suggested that cancer syndromes, such as neurofibromatosis type 1 and Li-Fraumeni syndrome, may partly explain the excesses. The associations of STTs with cancers of the skin (squamous cell carcinoma and melanoma) and with NHL may be related to immunodeficiency.

Heritable and environmental components in cervical tumors

The familial risk of 18,199 women with invasive and/or in situ cervix cancers when compared with that of 72,796 women free of cervical tumors was analyzed. The risk of cervical tumors was significantly higher for women with a mother and/or sister(s) with cervical tumors (odds ratio (OR) = 1.79, 95% CI: 1.71-1.88) than with an affected grandmother and/or aunt(s) (OR = 1.28, 1.22-1.35). This risk did not differ according to the family side of the affected relative. Taking the familial risk of 1.28 for second-degree relatives as the best estimate of a true heritable effect for 25% of gene sharing, the calculated heritable effect for full siblings, sharing 50% of their genes, would correspond to an OR of 1.56. This model suggests, as a best estimate, a heritable component of 71% and an environmental component of 29% in young familial cervical tumors. The data imply that familial risks for cervical tumors are best explained by complex multifactorial mechanisms.

Cancer characteristics in Swedish families fulfilling criteria for hereditary nonpolyposis colorectal cancer

BACKGROUND & AIMS

The present study quantified the prevalence of families that fulfill the Amsterdam or Bethesda criteria for hereditary nonpolyposis colorectal cancer (HNPCC) in the whole Swedish population and investigated the extent to which tumors in the classified families are HNPCC-related.

METHODS

The families of the Swedish Family-Cancer Database with at least 4 generations (N = 566,877) were classified according to the Amsterdam and the Bethesda criteria. Survival methods were used to assess the risk of cancer in the classified families, the prognosis of cancer patients, and the risk of subsequent malignancies after colorectal adenomas and after colorectal/endometrial adenocarcinomas.

RESULTS

The Bethesda criteria identified 0.9% of all Swedish families and 11.2% of patients with colorectal cancer. Families that fulfilled the Bethesda criteria showed increased risks of cancer in the colorectum, endometrium, small bowel, ovary, stomach, bile ducts, renal pelvis, and ureter; members of Bethesda criteria families were at decreased risks of lung and cervical cancers. The prognosis of cancer in the ureter, renal pelvis, stomach, ovary, and colorectum, but not in the endometrium, was better in Bethesda criteria than in nonclassified families.

CONCLUSIONS

Most malignancies in the classified families reflect typical features of HNPCC (association with subsequent malignancies, accelerated adenoma-carcinoma sequence, and better survival). The data presented in this study should help to define surveillance strategies for members of families that fulfill the criteria for HNPCC testing.

Familial Risk of Cancer Shortly After Diagnosis of the First Familial Tumor

BACKGROUND

The diagnosis of the first cancer in a family may lead to the medical examination of the patient's relatives and the subsequent identification of additional familial cancers. If detection bias is present, familial risks could be overestimated soon after first diagnosis.

METHODS

We followed 1,677,722 offspring/siblings of 846,448 probands from the year of diagnosis of the first familial tumor to the diagnosis of first cancer, death, emigration, or December 31, 2002, using the Swedish Family Cancer Database. The risks of cancer among the offspring and siblings of patients with melanoma and cancers of the breast, prostate, colorectum, cervix, and lung were compared with those in the general population. Relative risks (RRs) were determined using Poisson regression, according to the time after first diagnosis. All statistical tests were two-sided.

RESULTS

Daughters of women with breast cancer had a statistically significantly higher relative risk of in situ breast cancer during the year of the mother's diagnosis than they did 5 or more years later (RR = 4.78, 95% confidence interval [CI] = 2.16 to 10.6, 26.6 cases per 100,000, versus RR = 1.97, 95% CI = 1.65 to 2.37, 27.2 cases per 100,000; P = .033). Daughters diagnosed the same year as their mothers were younger and were diagnosed earlier in the calendar year than daughters of women diagnosed 5 or more years after their mothers. Similarly, the risk of invasive melanoma among the offspring of individuals with invasive melanoma was higher during the year of the parent's diagnosis than it was 5 or more years afterward (RR = 8.27, 95% CI = 3.82 to 17.9, 57.0 cases per 100,000, versus RR = 3.18, 95% CI = 2.55 to 3.97, 37.6 cases per 100,000; P = .019). Sibling risks of in situ breast cancer, in situ cervical cancer, and invasive prostate cancer also decreased with time after diagnosis of the first familial tumor.

CONCLUSIONS

Increased surveillance may result in the earlier detection of asymptomatic familial cancers, i.e., in detection bias. The possibility of overestimated familial risks of cancer shortly after diagnosis of the first familial tumor should be considered before a patient's clinical and genetic counseling is implemented.

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.