Parental cancer as a risk factor for brain tumors (Sweden)

Ionizing radiation exposure during adulthood and risk of developing central nervous system tumors: systematic review and meta-analysis

Many studies on ionizing radiation (IR) exposure during childhood have shown deleterious effects on the central nervous system (CNS), however results regarding adult exposure are inconsistent, and no systematic reviews have been performed. The objectives are to synthesize the findings and draw evidence-based conclusions from epidemiological studies on the risk of benign and malignant brain and CNS tumors in humans exposed to low-to-moderate doses (< 0.5 Gy) of IR during adulthood/young adulthood. A systematic literature search of four electronic databases, supplemented by a hand search, was performed to retrieve relevant epidemiological studies published from 2000 to 2022. Pooled excess relative risk (ERR_pooled) was estimated using a random effect model. Eighteen publications were included in the systematic review and twelve out of them were included in a meta-analysis. The following IR sources were considered: atomic bombs, occupational, and environmental exposures. No significant dose-risk association was found for brain/CNS tumors (ERR_pooled at 100 mGy = − 0.01; 95% CI: − 0.05, 0.04). Our systematic review and meta-analysis did not show any association between exposure to low-to-moderate doses of IR and risk of CNS tumors. Further studies with histological information and precise dose assessment are needed.

Intracranial meningioma in two coeval adult cats from the same litter

Case summary

In this report we describe the occurrence of intracranial meningioma in two adult cats from the same litter. The location of the meningioma varied: one tumour was at the level of the brainstem, and the other was affecting the temporal and piriform lobes. The cat with the brainstem meningioma was treated with radiotherapy and the littermate had a rostrotentorial craniectomy for tumour removal. Both cats had a histopathological diagnosis of grade I meningioma of a predominantly fibrous subtype.

Relevance and novel information

Cases of familial meningioma in cats have not previously been described in the veterinary literature. However, familial meningioma is well described in humans and it is possible that cases are underestimated in animals. We discuss the possible genetic background and other causes, as well as challenges we may face in veterinary medicine in identifying these associations.

Tyrosine kinase inhibitors and their unique therapeutic potentialities to combat cancer

Cancer is one of the leading causes of death with a mortality rate of 12%. Although significant progress has been achieved in cancer research, the effective treatment of cancer remains the greatest global challenge in medicine. Dysregulation of tyrosine kinases (TK) is one of the characteristics of several types of cancers. Thus, drugs that target and inhibit these enzymes, known as TK inhibitors (TKIs), are considered vital chemotherapeutics to combat various types of cancer. The oral bioavailability of available TKIs and their targeted therapy are their potential benefits. Based on these characteristics, most TKIs are included in first/second-line therapy for the treatment of different cancers. This review aims to shed light on orally-active TKIs (natural and synthetic molecules) and their promising implication in the therapy of numerous types of tumors along with their mechanisms of action. Further, recent progress in the development of synthetic and isolation of natural TKIs is reviewed. A significant growth in research regarding the development of new-generation TKIs is made with time (23 FDA-approved TKIs from 2018) due to their better therapeutic response. Oral bioavailability should be considered as an important parameter while developing of new-generation TKIs; however, drug delivery systems can also be used to address issue of poor bioavailability to a certain extent. Moreover, clinical trials should be designed in consideration of the development of resistance and tumor heterogeneity.

Risk factors for gliomas. An extensive review

Primary brain tumors consist are a heterogenic group of malignancies. Gliomas represent subtypes which include all tumors arising from glial cells. The risk factors for gliomas are until today unclear. The aim of this study was to summarize all possible connections between suspected risk factors and glial brain tumors.

Description of selected characteristics of familial glioma patients - results from the Gliogene Consortium

BACKGROUND

While certain inherited syndromes (e.g. Neurofibromatosis or Li-Fraumeni) are associated with an increased risk of glioma, most familial gliomas are non-syndromic. This study describes the demographic and clinical characteristics of the largest series of non-syndromic glioma families ascertained from 14 centres in the United States (US), Europe and Israel as part of the Gliogene Consortium.

METHODS

Families with 2 or more verified gliomas were recruited between January 2007 and February 2011. Distributions of demographic characteristics and clinical variables of gliomas in the families were described based on information derived from personal questionnaires.

FINDINGS

The study population comprised 841 glioma patients identified in 376 families (9797 individuals). There were more cases of glioma among males, with a male to female ratio of 1.25. In most families (83%), 2 gliomas were reported, with 3 and 4 gliomas in 13% and 3% of the families, respectively. For families with 2 gliomas, 57% were among 1st-degree relatives, and 31.5% among 2nd-degree relatives. Overall, the mean (±standard deviation [SD]) diagnosis age was 49.4 (±18.7) years. In 48% of families with 2 gliomas, at least one was diagnosed at <40y, and in 12% both were diagnosed under 40y of age. Most of these families (76%) had at least one grade IV glioblastoma multiforme (GBM), and in 32% both cases were grade IV gliomas. The most common glioma subtype was GBM (55%), followed by anaplastic astrocytoma (10%) and oligodendroglioma (8%). Individuals with grades I-II were on average 17y younger than those with grades III-IV.

INTERPRETATION

Familial glioma cases are similar to sporadic cases in terms of gender distribution, age, morphology and grade. Most familial gliomas appear to comprise clusters of two cases suggesting low penetrance, and that the risk of developing additional gliomas is probably low. These results should be useful in the counselling and clinical management of individuals with a family history of glioma.

Family history of cancer in benign brain tumor subtypes versus gliomas

Purpose: Family history is associated with gliomas, but this association has not been established for benign brain tumors. Using information from newly diagnosed primary brain tumor patients, we describe patterns of family cancer histories in patients with benign brain tumors and compare those to patients with gliomas. Methods: Newly diagnosed primary brain tumor patients were identified as part of the Ohio Brain Tumor Study. Each patient was asked to participate in a telephone interview about personal medical history, family history of cancer, and other exposures. Information was available from 33 acoustic neuroma (65%), 78 meningioma (65%), 49 pituitary adenoma (73.1%), and 152 glioma patients (58.2%). The association between family history of cancer and each subtype was compared with gliomas using unconditional logistic regression models generating odds ratios (ORs) and 95% confidence intervals. Results: There was no significant difference in family history of cancer between patients with glioma and benign subtypes. Conclusion: The results suggest that benign brain tumor may have an association with family history of cancer. More studies are warranted to disentangle the potential genetic and/or environmental causes for these diseases.

Family and personal medical history and risk of meningioma

OBJECT

Little is known about the epidemiology of meningioma, the most frequently reported primary brain tumor in the US. The authors undertook a case-control study to examine the relationship between family and personal medical history and meningioma risk.

METHODS

The authors compared the personal and first-degree family histories of 1124 patients with meningioma (age range 20-79 years) in Connecticut, Massachusetts, North Carolina, the San Francisco Bay Area, and 8 Houston counties between May 1, 2006, and February 26, 2010, and the histories of 1000 control individuals who were frequency-matched for age, sex, and geography.

RESULTS

The patients were more likely than the controls to report a first-degree family history of meningioma (OR 4.4, 95% CI 1.6-11.5), and there was an even stronger association in younger cases. The patients were less likely than controls to report immune conditions including allergy (OR 0.6, 95% CI 0.5-0.7) but were more likely to report a history of thyroid cancer (OR 4.7, 95% CI 1.02-21.5) or leukemia (OR 5.4, 95% CI 1.2-24.1) (most after radiotherapy). Among women, patients were more likely than controls to report hormonally related conditions--uterine fibroid tumors (OR 1.2, 95% CI 1.0-1.5), endometriosis (OR 1.5, 95% CI 1.5-2.1), and breast cancer (OR 1.4, 95% CI 0.8-2.3).

CONCLUSIONS

The influence of genetics, the immune system, and radiation near the head on meningioma risk is suggested in the authors' findings; the role of hormones is intriguing but requires further study.

Familial aggregation of glioma: a pooled analysis

In genome-wide association studies, inherited risk of glioma has been demonstrated for rare familial syndromes and with common variants from 3-5 chromosomal regions. To assess the degree of familial aggregation of glioma, the authors performed a pooled analysis of data from 2 large glioma case-control studies in the United States (MD Anderson Cancer Center, Houston, Texas (1994-2006) and University of California, San Francisco (1991-2004)) and from the Swedish Cancer Registry (1958-2006) to measure excess cases of cancer among first-degree relatives of glioma probands. This analysis included 20,377 probands with glioma and 52,714 first-degree relatives. No overall increase was found in the expected number of cancers among family members; however, there were 77% more gliomas than expected. There were also significantly more sarcoma and melanoma cases than expected, which is supported by evidence in the literature, whereas there were significantly fewer-than-expected cases of leukemia, non-Hodgkin lymphoma, and bladder, lung, pancreatic, prostate, and uterine cancers. This large pooled analysis provided sufficient numbers of related family members to examine the genetic mechanisms involved in the aggregation of glioma with other cancers in these families. However, misclassification due to unvalidated cancers among family members could account for the differences seen by study site.

Links between private habits, psychological stress and brain cancer: a case-control pilot study in France

Numerous studies have increasingly suggested that medical history and lifestyle factors could be involved in the increase of cancer risk in adults. The issue whether psychological factors can influence the development of cancer has been discussed for many years. In the field of brain cancer, psychological stress has not so far been investigated. We conducted a French case-control pilot study with 122 adult incident cases and 122 controls free of any cancer diagnosis, matched for age and gender, to investigate links between malignant primitive brain tumours (MPBT) and medical history, private habits and psychological stress. Data were collected through self-administered questionnaires, and person-to-person interviews. To complete the psychological stress assessment, 100-mm visual analog scales were used. After adjustment for confounders, we found no significant effect of head trauma, aspartame, tobacco or alcohol consumption, place (rural or urban) of residence, sociodemographic data, and experience of psychological stress at work/home. Our results showed a significant association between MPBT risk and major life events over the past 5 years before diagnosis (OR = 1.90, 95% CI 1.13-3.20), family histories of cancer (OR = 1.90, 95% CI 1.12-3.22), fresh vegetable and fruit intake (OR = 0.29, 95% CI 0.09-0.95), and skipped meals several times per week (OR = 0.35, 95% CI 0.16-0.77). The present study suggests the role of genetic factors in glioma risk, and also suggests that an acute and sudden psychological stress might influence MPBT appearance. Additional large clinical studies are needed to confirm these findings.

Familial risks in nervous system tumours: joint Nordic study

Background:

Familial nervous system cancers are rare and limited data on familial aspects are available particularly on site-specific tumours.

Methods:

Data from five Nordic countries were used to analyse familial risks of nervous system tumours. Standardised incidence ratios (SIRs) were calculated for offspring of affected relatives compared with offspring of non-affected relatives.

Results:

The total number of patients with nervous system tumour was 63 307, of whom 32 347 belonged to the offspring generation. Of 851 familial patients (2.6%) in the offspring generation, 42 (4.7%) belonged to the families of a parent and at least two siblings affected. The SIR of brain tumours was 1.7 in offspring of affected parents; it was 2.0 in siblings and 9.4 in families with a parent and sibling affected. For spinal tumours, the SIRs were much higher for offspring of early onset tumours, 14.0 for offspring of affected parents and 22.7 for siblings. The SIRs for peripheral nerve tumours were 16.3 in offspring of affected parents, 27.7 in siblings and 943.9 in multiplex families.

Conclusion:

The results of this population-based study on medically diagnosed tumours show site-, proband- and age-specific risks for familial tumours, with implications for clinical genetic counselling and identification of the underlying genes.

Familial risks in nervous-system tumours: a histology-specific analysis from Sweden and Norway

BACKGROUND

There are limited data available on tumour subtype-specific familial risks for nervous-system tumours. We aimed to provide such data at the population level.

METHODS

We used data from the nationwide Swedish and Norwegian databases on familial cancer to calculate standardised incidence ratios (SIRs) for the familial risk of developing a nervous-system tumour in offspring born after 1931 (Sweden) or 1900 (Norway) whose parents or siblings were probands.

FINDINGS

54 195 patients had nervous-system tumours, 22 331 of whom belonged to the offspring generation aged 0-72 years in Sweden and 0-51 years in Norway. Of 709 familial patients in the offspring generation, 438 (61.8%) had a parent affected by a nervous-system tumour (SIR 1.66; 95% CI 1.51-1.82), 236 (33.3%) had a sibling affected by a nervous-system tumour (SIR 2.01; 95% CI 1.76-2.28), and 35 (4.9%) belonged to families with a parent and at least two siblings affected by a nervous-system tumour (multiplex families; SIR 13.40; 95% CI 9.33-18.66). The SIR for glioma was 1.8 (1.5-2.0) when a parent was a proband, but increased to 11.2 (5.7-19.5) in multiplex families. Early-onset neurinoma and haemangioma showed high familial risks; with an SIR for neurinoma of 1.7 (1.4-2.2) for offspring of affected parents, 2.7 (2.0-3.5) for siblings, and 27.2 (13.5-48.8) for multiplex families, and an SIR for haemangioma of 2.4 (1.4-3.8) for offspring of affected parents. Histology-specific population-based familial risks were shown for meningioma (1.6 for offspring of affected parents; 95% CI 1.3-2.0), ependymoma (2.7 for young offspring <20 years; 1.1-5.5), medulloblastoma (4.1 for siblings; 1.7-8.1), and neuroblastoma (3.2 for siblings; 1.1-6.9).

INTERPRETATION

Our results suggest a complex genetic background for nervous-system tumours, which differs depending on the age of onset and histological subtype of the tumour. High sibling risks might suggest recessive inheritance. As the high-penetrant multiplex families only accounted for about 5% of familial nervous-system tumours, most familial cases are probably caused by low-penetrance genes.

FUNDING

The Nordic Cancer Union, Deutsche Krebshilfe, the Swedish Cancer Society, and the Swedish Council for Working Life and Social Research.

Familiality in brain tumors

BACKGROUND

Familiality in brain tumors is not definitively substantiated.

METHODS

We used the Utah Population Data Base (UPDB), a genealogy representing the Utah pioneers and their descendants, record-linked to statewide cancer records, to describe the familial nature of primary brain cancer. We examined the familial clustering of primary brain tumors, including subgroups defined by histologic type and age at diagnosis. The UPDB includes 1,401 primary brain tumor cases defined as astrocytoma or glioblastoma, all with at least three generations of genealogy data. We tested the hypothesis of excess relatedness of brain tumor cases using the Genealogical Index of Familiality method. We estimated relative risks for brain tumors in relatives using rates of brain tumors estimated internally.

RESULTS

Significant excess relatedness was observed for astrocytomas and glioblastomas considered as a group (n = 1,401), for astrocytomas considered separately (n = 744), but not for glioblastomas considered separately (n = 658). Significantly increased risks to first- and second-degree relatives for astrocytomas were identified for relatives of astrocytomas considered separately. Significantly increased risks to first-degree relatives, but not second degree, were observed for astrocytoma and glioblastoma cases considered together, and for glioblastoma cases considered separately.

CONCLUSIONS

This study provides strong evidence for a familial contribution to primary brain cancer risk. There is evidence that this familial aspect includes not only shared environment, but also a heritable component. Extended high-risk brain tumor pedigrees identified in the UPDB may provide the opportunity to identify predisposition genes responsible for familial brain tumors.

Aggregation of cancer in first-degree relatives of patients with glioma

BACKGROUND

Previous studies have been inconclusive in estimating the risk of different cancer sites among close relatives of glioma patients; however, malignant melanoma has consistently been described.

METHODS

We obtained family history information from 1,476 glioma patients under age 75 years who registered at M. D. Anderson Cancer Center between June 1992 and June 2006. The number of observed cancers (N=1,001) among 8,746 first-degree relatives (FDR) was compared with the number expected from age-, sex-, and calendar year-specific rates from the Surveillance, Epidemiology, and End Results Program using standardized incidence ratios (SIR).

RESULTS

The overall SIR for any cancer was 1.21 (95% confidence interval, 1.14-1.29). Among FDRs under 45 years the overall SIR was 5.08, and for relatives >45 years the overall SIR was 0.95. The SIRs were significantly elevated for brain tumors (2.14), melanoma (2.02), and sarcoma (3.83). We observed an excess of pancreatic cancer, which was significantly higher only among mothers.

CONCLUSION

We observed an overall 21% increase in cancer among the FDRs of glioma patients including excess cases of brain tumors and melanoma, which could point to similar genetic contributions to these two malignancies. A large international linkage study is under way to examine potential genomic regions important for familial glioma.

Epidemiology of brain tumors

Brain tumors seemed to have increased in incidence over the past 30 years, but the rise probably results from use of new neuroimaging techniques. Treatments have not improved prognosis for rapidly fatal brain tumors. Established brain tumor risk factors (exposure to ionizing radiation, rare mutations of penetrant genes, and familial history) explain only a small proportion of brain tumors, and only one of these potentially is modifiable. Genetic and environmental characteristics likely play a role in familial aggregation of glioma and these factors are not identified. New concepts in brain tumor etiology and clinical management are the goal of research, with an aim at eradicating this devastating disease.

GLIOGENE an International Consortium to Understand Familial Glioma

Evidence for familial aggregation of glioma has been documented in both case-control and cohort studies and occurs apart from the well-described rare inherited genetic syndromes involving glioma: neurofibromatosis type 1 and 2, tuberous sclerosis, Turcot's syndrome, and Li-Fraumeni syndrome. Nonsyndromic glioma families have been studied but no genes have been identified in the two published linkage studies of familial glioma probably due to the small number of families. Because glioma is a rare but devastating cancer, and a family history of glioma has been observed in approximately 5% of the cases, we initiated an international consortium to identify glioma families not affected by syndromes to better understand the inherited factors related to this disease. The international consortium GLIOGENE is an acronym for "glioma gene" and includes 15 research groups in North America, Europe, and Israel to study familial glioma. The overarching goal is to characterize genes in glioma families using a genome-wide single-nucleotide polymorphism approach and conducting linkage analysis to identify new genomic regions or loci that could harbor genes important for gliomagenesis. Here, we review the rationale for studying familial glioma and our proposed strategy for the GLIOGENE study.

Anaplastic astrocytoma in adults

Anaplastic astrocytoma is an uncommon disease in the adult population. Prognosis is influenced by age, symptom duration, mental status and Karnofsky performance status. A truly complete resection, which is a recognized independent prognostic factor, is not possible and recurrence in the surgical cavity is common. Based on randomized data available, chemotherapy has consistently failed to improve the outcome of patients with anaplastic astrocytoma, while a meta-analysis showed a small, but significant improvement in survival favouring the use of chemotherapy. Outside a clinical trial, postoperative radiotherapy (30 x 2 Gy) remains the standard adjuvant therapy for most patients. For elderly patients, the application of treatment is usually based on performance status and neurological function. In recurrent disease, chemotherapy with temozolomide has been proven to be active and well-tolerated in phase II trials, but no comparative phase III trials of other cytotoxic drugs have been conducted.

Epidemiology of intracranial meningioma

Meningiomas are the most frequently reported primary intracranial neoplasms, accounting for approximately 25% of all such lesions diagnosed in the United States. Few studies have examined the risk factors associated with a diagnosis of meningioma with two categories of exposure, hormones (both endogenous and exogenous) and radiation, most strongly associated with meningioma risk. Limited data are also available on long-term outcomes for meningioma patients, although it is clear that the disease is associated with significant morbidity and mortality. Recent legislation passed in the United States (The Benign Brain Tumor Cancer Registries Amendment Act [H.R. 5204]) mandates registration of benign brain tumors such as meningioma. This will increase the focus on this disease over the coming years as well as likely increase the reported prevalence of the disease. The increased emphasis on research dedicated to the study of brain tumors coupled with the advent of new tools in genetic and molecular epidemiology make the current era an ideal time to advance knowledge for intracranial meningioma. This review highlights current knowledge of meningioma epidemiology and new directions for research efforts in this field.

Meningioma and schwannoma risk in adults in relation to family history of cancer

Relatively little is known about factors that contribute to the development of meningioma and vestibular schwannoma, two intracranial nervous system tumors. We evaluated the risk of these tumors in relation to family history of malignant or benign tumors. Incident cases of meningioma (n = 197) or schwannoma (n = 96) were identified at three U. S. referral hospitals between June 1994 and August 1998. Controls (n = 799) admitted to the same hospitals for nonmalignant conditions were matched to cases on age, sex, race/ethnicity, hospital, and proximity of residence to hospital. We found that risk of meningioma was increased among persons reporting a family history of a benign brain tumor (odds ratio [OR], 4.5; 95% confidence interval [CI], 1.0-21.0; n = 5) or melanoma (OR, 4.2; 95% CI, 1.2-15.0; n 5). A family history of breast cancer was associated with an elevated meningioma risk among participants aged 18 to 49 years (OR, 3.9; 95% CI, 1.4-11.0; n = 8) but a reduced risk among older respondents (OR, 0.2; 95% CI, 0.1-0.7; n = 3). Family history of cancer did not differ between schwannoma cases and controls, although the statistical power to detect associations was limited. Some relative risk estimates were based on a small number of observations and may have arisen by chance. Inheritance of predisposing genes, shared environmental factors, or both within families with a history of benign brain tumors, melanoma, or possibly breast cancer may be related to altered meningioma risk.

Association of brain tumours with other neoplasms in families

We used the nationwide Swedish Family-Cancer Database to analyse the association of histology-specific brain tumours with other cancers in family members. Among 0-68-year-old offspring, 9414 patients with brain tumours were identified from 1961 to 2000, of whom, 3387 parents were diagnosed with any primary neoplasm. Astrocytoma, meningioma and neurinoma were the main histological types. Increased standardised incidence ratios (SIRs) were found for brain tumours in association with cancers at sites that are known features in recognised syndromes, such as haemangioblastoma and renal cancer in von Hippel-Lindau disease. In addition, an association between astrocytoma and melanoma was recognised. Among as yet unknown clustering, neurinoma was associated with testicular cancer and myeloma; meningioma was associated with cervical cancer; astrocytoma was associated with prostate cancer; ependymoma was associated with breast cancer. Although some of these may feature a true tumour cluster, they need to be confirmed in another setting.

Genetic epidemiology of cancer: From families to heritable genes

A reliable determination of familial risks for cancer is important for clinical counseling, prevention and understanding cancer etiology. Family-based gene identification efforts may be targeted if the risks are well characterized and the mode of inheritance is identified. Medically verified data on familial risks have not been available for all types of cancer but they have become available through the use of the nationwide Swedish Family-Cancer Database, which includes all Swedes born in 1932 and later with their parents, totaling over 10 million individuals. Over 150 publications have emanated from this source. The familial risks of cancer have been characterized for all main cancers and the contribution of environmental and heritable effects to the familial aggregation has been assessed. Furthermore, the mode of inheritance has been deduced by comparing risks from parental and sibling probands. Examples are shown on familial clustering of cancers, for which heritable susceptibility genes are yet unknown, such as squamous cell carcinoma of the skin, intestinal carcinoids, thyroid papillary tumors, brain astrocytomas and pituitary adenomas. Some common cancers, such as lung and kidney cancers, appear to show an early-onset recessive component because familial risks among siblings are much higher than those in families where parents are probands. Many of the cancer sites showing high familial risks lack guidelines for clinical counseling or action level. In conclusion, we recommend that any future gene identification efforts, either using linkage or association designs, devise their strategies based on data from family studies. Clinical genetic counseling would benefit from reviewing established familial risks on all main types of cancer.

Familial and attributable risks in cutaneous melanoma: effects of proband and age

We studied familial risks in invasive and in situ cutaneous melanoma by comparing the occurrence of melanoma, or discordant cancer, between parents and offspring, and between siblings, based on the Swedish Family Cancer Database of over 10 million individuals. Offspring were 0-66 y of age. Cancers were obtained from the Swedish Cancer Registry from 1961 to 1998. The study was based on 24,818 invasive and 5510 in situ cases of melanoma. Standardized incidence ratios were calculated for familial risk. The standardized incidence ratios for offspring was 2.40 (95% confidence intervals: 2.10-2.72) when only the parent had melanoma and it was 2.98 (95% confidence intervals: 2.54-3.47) when only a sibling was affected; when both a parent and a sibling were affected the standardized incidence ratios was 8.92 (95% confidence intervals: 4.25-15.31). The respective population attributable risks were 1.38, 1.20, and 0.10%. The familial risk showed a clear age dependence and somewhat higher risk in in situ melanoma than in the invasive counterpart. The highest standardized incidence ratio of 61.78 (5.82-227.19) was noted for offspring whose parent had multiple melanomas. Superficially spreading melanoma showed the highest familial risk both among invasive and in situ tumors. Melanoma associated with breast, nervous system, and skin cancers, and in situ melanoma possibly also with connective tissue and thyroid tumors and multiple myeloma.

Familial risk of cancer by site and histopathology

Familial risks for histopathology-specific cancers have not been determined. We used the nationwide Swedish Family-Cancer Database on 10.2 million individuals and 1 million tumors to calculate standardized incidence ratios (SIRs) for familial cancers of specific histology and morphology among 0- to 66-year-old offspring. We used histology codes for both offspring and parents, but because of the limited number of cases, the morphology-specific classification could be used only for offspring by all site-specific cancers in parents, resulting in inflated risk estimates. A number of novel findings emerged in the histopathology-specific analysis of familial risks, in addition to some known associations. Overall, specific histology showed an SIR of 2.07 for all cancers compared to an SIR of 2.00 for any histology. However, the small effect was due to breast and prostate cancers, which showed a negligible effect of specific histology. Familial risks of over 4.0 were found for serous papillary cystadenocarcinoma of the ovary, papillary thyroid cancer and low-grade astrocytoma. Familial risks of over 3.0 were found for signet-ring gastric cancer, various forms of ovarian cancer and squamous cell skin cancer. Also noteworthy were familial risks of hepatocellular carcinoma (2.48), pancreatic adenocarcinoma (1.92), large cell carcinoma and adenocarcinoma of the lung (2.29 and 2.18, respectively) and clear cell carcinoma of the kidney (2.73). Many of the findings were novel and could be revealed only by applying codes for specific histopathology. These data call for a closer description of familial aggregations and probing for the underlying genetic mechanisms.

Different aetiology of familial low-grade and high-grade glioma? A nationwide cohort study of familial glioma

An increased risk for first-degree relatives (FDR) of glioma patients has previously been observed. The novel objective of this study was to investigate differences in familial risk among FDR of low-grade glioma (LGG) and high-grade glioma (HGG) cases, respectively. Two cohorts were constructed, one from 15,321 FDR of LGG cases and the other from 26,635 FDR of HGG cases calculating standardised incidence ratios (SIR). The risk for LGG among FDR of LGG cases was significantly increased, SIR 3.65 (95% CI 2.31-5.47). The risk was even higher in the cohort of siblings, SIR 7.00 (95% CI 3.35-12.87), and especially in the younger siblings (<40 years), SIR 9.01 (95% CI 4.31-16.57). When calculating the risk for HGG in the LGG cohort and the risk for HGG in the HGG cohort, there was a generally twofold increased risk, but no trends of increased risk in relatives of younger probands. Two different methods calculating familial risk displayed similar results. LGG families apparently have features manifesting a distinct pedigree pattern with sibpairs affected at a young age. These families could provide new insights into the aetiology of glioma.