Familial relationships in thyroid cancer by histo-pathological type

Clinical relevance and outcome of familial papillary thyroid cancer: a single institution study of 626 familial cases

Background

Whether familial thyroid cancer is more aggressive than sporadic thyroid cancer remains controversial. Additionally, whether the number of affected family members affects the prognosis is unknown. This study focused mainly on the comparison of the clinicopathological characteristics and prognoses between papillary thyroid cancer (PTC) patients with and without family history.

Methods

A total of 626 familial papillary thyroid cancer (FPTC) and 1252 sporadic papillary thyroid cancer (SPTC) patients were included in our study. The clinical information associated with FPTC and SPTC was recorded and analyzed by univariate analysis.

Results

Patients in the FPTC group had a higher rate of multifocality (p=0.001), bilaterality (p=0.000), extrathyroidal invasion (p=0.000), distant metastasis (p=0.012), lymph node metastasis (p=0.000), recurrence (p=0.000), a larger tumor size (p=0.000) and more malignant lymph nodes involved (central: p=0.000; lateral: p=0.000). In addition, our subgroup analysis showed no significant difference (p>0.05) between patients with only one affected family member and those with two of more group in all clinicopathological characteristics. In papillary thyroid microcarcinoma (PTMC) subgroup analysis, we found that FPTMC patients harbored significantly larger tumors (p=0.000), higher rates of multifocality (p=0.014), bilaterality (p=0.000), distant metastasis (p=0.038), lymph node metastasis (p=0.003), greater numbers of malignant lymph nodes (central: p=0.002; lateral: p=0.044), higher rates of I-131 treatment (p=0.000) and recurrence (p=0.000) than SPTMC patients.

Conclusion

Our results indicated that PTC and PTMC patients with a positive family history had more aggressive clinicopathological behaviors, suggesting that more vigilant screening and management for FPTC may be helpful.

Early mortality critically impedes improvements in thyroid cancer survival through a half century

OBJECTIVES

We analyze survival in thyroid cancer from Denmark (DK), Finland (FI), Norway (NO), and Sweden (SE) over a 50-year period (1971-2020), and additionally consider concomitant changes in incidence and mortality.

DESIGN

Population-based survival study.

METHODS

Relative 1-, 5/1 (conditional)-, and 5-year survival data were obtained from the NORDCAN database for years 1971-2020. Incidence and mortality rates were also assessed.

RESULTS

A novel consistent observation was that 1-year survival was worse than 5/1-year survival but the difference between these decreased with time. Relative 1-year survival in thyroid cancer (mean for the 4 countries) reached 92.7% for men and 95.6% for women; 5-year survival reached 88.0% for men and 93.7% for women. Survival increased most for DK which started at a low level and reached the best survival at the end. Male and female incidence rates for thyroid cancer increased 3- and 4-fold, respectively. In the same time, mortality halved for men and for women, it decreased by 2/3.

CONCLUSIONS

We documented worse relative survival in the first year than in the 4 subsequent years, most likely because of rare anaplastic cancer. Overall survival in thyroid cancer patients increased in the Nordic countries in the course of 50 years; 5-year survival was close to 90% for men and close to 95% for women. Even though overdiagnosis may explain some of 5-year survival increase, it is unlikely to influence the substantial increase in 1-year survival. The unmet need is to increase 1-year survival by diagnosing and treating aggressive tumors before metastatic spread.

Current Knowledge of Germline Genetic Risk Factors for the Development of Non-Medullary Thyroid Cancer

The thyroid is the most common site of endocrine cancer. One type of thyroid cancer, non-medullary thyroid cancer (NMTC), develops from follicular cells and represents approximately 90% of all thyroid cancers. Approximately 5%–15% of NMTC cases are thought to be of familial origin (FNMTC), which is defined as the occurrence of the disease in three or more first-degree relatives of the patient. It is often divided into two groups: Syndrome-associated and non-syndromic. The associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex and Werner syndrome. The hereditary factors contributing to the unfavorable course of FNMTC remain poorly understood; therefore, considerable effort is being expended to identify contributing loci. Research carried out to date identifies fourteen genes (DICER1, FOXE1, PTCSC2, MYH9, SRGAP1, HABP2, BRCA1, CHEK2, ATM, RASAL1, SRRM2, XRCC1, TITF-1/NKX2.1, PTCSC3) associated with vulnerability to FNMTC that are not related to hereditary syndromes. In this review, we summarize FNMTC studies to date, and provide information on genes involved in the development of non-syndromic familial non-medullary thyroid cancers, and the significance of mutations in these genes as risk factors. Moreover, we discuss whether the genetic polymorphism rs966423 in DIRC3 has any potential as a prognostic factor of papillary thyroid cancer.

The impact of family history on non-medullary thyroid cancer

INTRODUCTION

Around 10% of patients with non-medullary thyroid cancer (NMTC) will have a positive family history for the disease. Although many will be sporadic, families where 3 first-degree relatives are affected can be considered to represent true familial non-medullary thyroid cancer (FNMTC). The genetic basis, impact on clinical and pathological features, and overall effect on prognosis are poorly understood.

METHODS

A literature review identified articles which report on genetic, clinical, therapeutic and screening aspects of FNMTC. The results are presented to allow an understanding of the genetic basis and the impact on clinical-pathological features and prognosis in order to inform clinical decision making.

RESULTS

The genetic basis of FNMTC is unknown. Despite this, significant progress has been made in identifying potential susceptibility genes. The lack of a test for FNMTC has led to a clinical definition requiring a minimum of 3 first-degree relatives to be diagnosed with NMTC. Although some have shown an association with multi-centric disease, younger age and increased rates of extra-thyroidal extension and nodal metastases, these findings are not supported by all. The impact of FNMTC is unclear with all groups reporting good outcome, and some finding an association with more aggressive disease. The role of screening remains controversial.

CONCLUSION

FNMTC is rare but can be diagnosed clinically. Its impact on prognostic factors and the subsequent role in influencing management is debated. For those patients who present with otherwise low-risk differentiated thyroid cancer, FNMTC should be included in risk assessment when discussing therapeutic options.

Diagnosis and Management of Hereditary Thyroid Cancer

Thyroid cancers are largely divided into medullary (MTC) and non-medullary (NMTC) cancers , depending on the cell type of origin. Familial non-medullary thyroid cancer (FNMTC) comprises about 5-15% of NMTC and is a heterogeneous group of diseases, including both non-syndromic and syndromic forms. Non-syndromic FNMTC tends to manifest papillary thyroid carcinoma , usually multifocal and bilateral . Several high-penetrance genes for FNMTC have been identified, but they are often confined to a few or single families, and other susceptibility loci appear to play a small part, conferring only small increments in risk. Familial susceptibility is likely to be due to a combination of genetic and environmental influences. The current focus of research in FNMTC is to characterise the susceptibility genes and their role in carcinogenesis. FNMTC can also occur as a part of multitumour genetic syndromes such as familial adenomatous polyposis , Cowden's disease , Werner's syndrome and Carney complex . These tend to present at an early age and are multicentric and bilateral with distinct pathology. The clinical evaluation of these patients is similar to that for most patients with a thyroid nodule. Medullary thyroid cancer (MTC) arises from the parafollicular cells of the thyroid which release calcitonin. The familial form of MTC accounts for 20-25% of cases and presents as a part of the multiple endocrine neoplasia type 2 (MEN 2) syndromes or as a pure familial MTC (FMTC). They are caused by germline point mutations in the RET oncogene on chromosome 10q11.2. There is a clear genotype-phenotype correlation, and the aggressiveness of FMTC depends on the specific genetic mutation, which should determine the timing of surgery.

Risk of thyroid cancer in relatives of patients with medullary thyroid carcinoma by age at diagnosis

The familial risk of medullary thyroid carcinoma (MTC alone or as part of multiple endocrine neoplasms, MEN2A/MEN2B) is high, so we aimed to answer open questions about the lifetime cumulative risk of thyroid cancer (LCRTC at 0-79 years) among relatives of MTC patients by age and sex. For this nationwide study, a cohort of 3217 first-/second-degree relatives (FDRs/SDRs) of 389 MTC patients diagnosed in 1958-2010 in the Swedish Family-Cancer Database was followed for the incidence of thyroid cancer. The LCRTC in female relatives of patients with early-onset MEN2B (diagnosis age <25 years) was 44-57%, representing 140-520 times increase over the risk in their peers without a family history of endocrine tumors (men: LCRTC=22-52%, 320-750 times) depending on the number of affected FDRs/SDRs. The LCRTC in female relatives of patients with late-onset MEN2B (diagnosis age ≥25 years) was about 15-43% (men=24%). The LCRTC among relatives of early-onset MTC-alone patients was 3-20%. The LCRTC among relatives of late-onset MTC-alone patients was 5-26%. The LCRTC in female relatives of MEN2A patients was 16-63% (men=52%). The relatives of patients with early-onset MTC exhibited a high tendency to develop early-onset thyroid cancer. Simply available data on the number of FDRs and even SDRs affected with MTC and their age at diagnosis were quite informative for the estimation of the risk of thyroid cancer in probands. In settings where genetic testing is not available or affordable for all, evidence-based cumulative risks reported in this nationwide study may help physicians to identify very high-risk individuals.

Family history of cancer and risk of sporadic differentiated thyroid carcinoma

BACKGROUND

Thyroid cancer incidence in the United States, particularly in women, has increased dramatically since the 1980s. Although the causes of thyroid cancer in most patients remain largely unknown, evidence suggests the existence of an inherited predisposition to development of differentiated thyroid carcinoma (DTC). Therefore, the authors explored the association between sporadic DTC and family history of cancer.

METHODS

In a retrospective hospital-based case-control study of prospectively recruited subjects who completed the study questionnaire upon enrollment, unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) as estimates of the DTC risk associated with first-degree family history of cancer.

RESULTS

The study included 288 patients with sporadic DTC and 591 cancer-free controls. Family history of thyroid cancer in first-degree relatives was associated with increased DTC risk (adjusted OR, 4.1; 95% CI, 1.7-9.9). All DTC cases in patients with a first-degree family history of thyroid cancer were cases of papillary thyroid carcinoma (PTC) (adjusted OR, 4.6; 95% CI, 1.9-11.1). Notably, the risk of PTC was highest in subjects with a family history of thyroid cancer in siblings (OR, 7.4; 95% CI, 1.8-30.4). In addition, multifocal primary tumor was more common among PTC patients with first-degree family history of thyroid cancer than among PTC patients with no first-degree family history of thyroid cancer (68.8% vs 35.5%, P = .01).

CONCLUSIONS

The study suggests that family history of thyroid cancer in first-degree relatives, particularly in siblings, is associated with an increased risk of sporadic PTC.

Prevalence, clinicopathologic features, and somatic genetic mutation profile in familial versus sporadic nonmedullary thyroid cancer

BACKGROUND

Although hereditary nonmedullary thyroid cancer is recognized as a distinct and isolated familial syndrome, the precise prevalence and genetic basis are poorly understood. Moreover, whether familial nonmedullary thyroid cancer (FNMTC) has a more aggressive clinical behavior is controversial. The objectives of this study were to determine the prevalence of FNMTC, and compare the extent of disease and tumor somatic genetic alteration in patients with familial and sporadic papillary thyroid cancer.

METHODS

The main study entry criterion was patients who had a thyroid nodule that required a clinical evaluation with fine-needle aspiration biopsy and or thyroidectomy. A family history questionnaire was used to determine the presence of familial and sporadic thyroid cancer. Thyroid nodule fine-needle aspiration biopsy samples and tumor tissue at the time of thyroidectomy were used to test for somatic genetic mutations (BRAF V600E, NRAS, KRAS, NTRK1, RET/PTC1, and RET/PTC3).

RESULTS

There were 402 patients with 509 thyroid nodules enrolled in the study. The prevalence of FNMTC was 8.8% in all patients with thyroid cancer and 9.4% in patients with only papillary thyroid cancer. None of the patients with FNMTC had another familial cancer syndrome. There was no significant difference in gender, tumor size, lymph node metastasis, and overall stage between sporadic and familial cases of thyroid cancer. Patients with FNMTC were younger at diagnosis than patients with sporadic papillary thyroid cancer (p < 0.002). Seventy-nine of the 504 thyroid nodules had somatic genetic mutations (29 BRAF V600E, 29 NRAS, 8 KRAS, 1 NTRK1, 4 RET/PTC1, and 8 RET/PTC3). There was no significant difference in the number or type of somatic mutations between sporadic and hereditary cases of papillary thyroid cancer.

CONCLUSIONS

We found a higher prevalence of FNMTC in patients with papillary thyroid cancer than previously reported. Patients with FNMTC present at a younger age. Somatic mutations and extent of disease are similar in sporadic and FNMTC cases.

Familial thyroid neoplasia: impact of technological advances on detection and monitoring

PURPOSE OF REVIEW

To weigh the clinical impact of new technological insights into heritable thyroid malignancies.

RECENT FINDINGS

Medullary thyroid carcinoma and familial nonmedullary thyroid cancers represent the small minority of thyroid cancers that are inherited. New insights into the genetic alterations and molecular mechanisms implicated in these tumors are serving to refine the clinical tools available for their initial diagnosis as well as subsequent follow-up. In addition to an analysis of rearranged during transfection mutations and calcitonin profiles in medullary thyroid carcinoma, this review includes emphasis on familial nonmedullary thyroid cancer syndromes, including genetic findings in familial papillary thyroid cancer, familial adenomatous polyposis, Cowden syndrome, Carney complex, and Werner syndrome.

SUMMARY

Genetic mutational information is increasingly available on medullary and familial nonmedullary thyroid cancer and their associated syndromes. The clinical significance of this information for affected patients and their families continues to undergo evaluation.

The patient with a thyroid nodule

Nodular thyroid disease is common in the United States and throughout the world. Although most thyroid nodules are benign in nature, certain clinical, radiographic, and cytologic features are associated with an increased risk of malignancy. A clear understanding of these risk factors assists in the decision-making process when evaluating a patient with a thyroid nodule. It is this process that ultimately determines whether or not a patient is referred for surgery. This article provides a framework for clinicians to risk-stratify and appropriately manage patients with thyroid nodules.

Familial nonmedullary thyroid carcinoma-clinical relevance and prognosis. A European multicenter study. ESES Vienna presentation

PURPOSE

Approximately 5% of differentiated thyroid carcinomas are of familial origin. These familial nonmedullary thyroid carcinomas (FNMTC) have an increased risk of multifocal disease and lymph node involvement. Consequently, higher recurrence rates and decreased disease-specific survival rates are described. The best surgical approach is discussed controversially.

PATIENTS AND METHODS

A survey among the international members of the German Society of Endocrine Surgeons revealed 20 families with two or more first-degree relatives with FNMTC. The mean age of the 41 patients (30 female, 11 male) with FNMTC was 40.6 years (18-73 years).

RESULTS

Total thyroidectomy was performed in 31 of 41 patients (76%). Ninety-five percent of the tumors were papillary carcinomas. Two of 41 patients had follicular carcinomas. Ten patients (24%) with papillary carcinomas were diagnosed with Hashimoto's thyroiditis. The mean tumor size was 1.45 cm. FNMTC was multifocal in 12 patients (29%). A systematic lymph node dissection was performed in 21 of 41 patients (51%). Lymph nodes metastases were found in seven of these 21 patients. Twenty-eight of the patients (68%) underwent postoperative radioiodine ablation. After a mean follow-up of 7.2 years, 39 patients (95%) were disease free. One patient developed local recurrence and lung metastases, 10 and 25 years, respectively, after initial diagnosis. Another patient died 2 years postoperatively from advanced metastatic disease.

CONCLUSIONS

FNMTC is associated with an early onset of small, mostly papillary thyroid carcinomas and an increased risk of multifocality and lymph node involvement. Total thyroidectomy and systematic neck dissection are recommended together with radioiodine ablation. Screening for first-degree relatives should start at age 18 years.

Review Article: The Familial Counterparts of Follicular Cell—Derived Thyroid Tumors

The follicular cell—derived thyroid cancers (termed nonmedullary thyroid cancers—NMTCs) occur mostly sporadically, but intriguingly, NMTC has the highest familial risk among all cancer sites. This epidemiological observation is strengthened by the clinical occurrence of NMTC in familial aggregation (FNMTC) and by the detection of chromosomal loci in linkage with the disease phenotype. FNMTC loci have been proposed at 14q, 1q21, 19p13.2, 2q21, 8p23, 8q24, 1q21, and 6q22, but to date, no causative mutations have been linked to FNMTCs. In this review, the authors focus on the clinical, morphological, and molecular aspects that characterize familial tumors. Some morphological patterns may alert for a familial disease. FNMTCs share several of the somatic molecular changes associated with sporadic tumors. New genes affected by somatic changes have been disclosed within regions harboring FNMTC loci.

Family history of thyroid cancer and the risk of differentiated thyroid cancer in French polynesia

BACKGROUND

Differentiated thyroid carcinoma is considered to be the nonhereditary cancer for which familial inheritance is the highest. To date, no familial aggregation analysis of this cancer has been performed in Maohi populations, which exhibit a very high incidence rate. Therefore, we evaluate the risk of differentiated thyroid cancer associated with a family history of thyroid cancer in natives of French Polynesia.

METHODS

We investigated thyroid cancer incidence in the first-degree relatives of 225 cases of differentiated thyroid carcinomas diagnosed between 1979 and 2004 in patients born in French Polynesia, and 368 randomly selected population controls matched for sex and age, born and residing in French Polynesia. All but five thyroid cancers declared among relatives were validated.

RESULTS

Twenty-four cases declared a family history of thyroid cancer, when compared with 11 controls. Individuals with an affected first-degree relative had a 4.5-fold (95% confidence interval [CI], 1.9-10.6) increased risk of differentiated thyroid cancer. This odds ratio (OR) was not significantly higher when a male first-degree relative was affected (OR, 10.0; 95% CI, 1.3-74.8) compared with a female (OR, 4.0; 95% CI, 1.5-10.3) and was not different for patients who had a nonaggressive thyroid microcarcinoma (OR, 3.5; 95% CI, 0.6-16.4) than those who had a larger cancer (OR, 6.0; 95% CI, 1.8-20.5). This OR was borderline significantly (p, 0.07) higher in Maohis (OR, 11.0; 95% CI, 2.4-48.8) than in individuals of mixed origin (OR, 2.1; 95% CI, 0.8-5.9).

CONCLUSION

Our study shows that the familial inheritance of differentiated thyroid cancer is particularly high in Maohi populations.

Clinical features and genetic predisposition to hereditary nonmedullary thyroid cancer

BACKGROUND

Approximately 5% of the nonmedullary thyroid cancers are hereditary. Hereditary nonmedullary thyroid cancer may occur as a minor component of familial cancer syndromes (familial adenomatous polyposis, Gardner's syndrome, Cowden's disease, Carney's complex type 1, Werner's syndrome, and papillary renal neoplasia) or as a primary feature (familial nonmedullary thyroid cancer [FNMTC]). The goal of this article was to review our current knowledge on the hereditary nonmedullary thyroid cancer.

SUMMARY

Epidemiologic and clinical kindred studies have demonstrated that FNMTC is a unique clinical entity. Most studies suggest that FNMTC is associated with more aggressive disease than sporadic cases, with higher rates of multicentric tumors, lymph node metastasis, extrathyroidal invasion, and shorter disease-free survival. A hereditary predisposition to nonmedullary thyroid cancer is well established, but the susceptibility genes for isolated FNMTC have not been identified. However, additional susceptibility loci for FNMTC have been recently identified in classic isolated cases of FNMTC (1q21, 6q22, 8p23.1-p22, and 8q24).

CONCLUSIONS

More studies are needed to validate chromosomal susceptibility loci and identify the susceptibility genes for FNMTC. The discovery of the predisposing genes may allow for screening and early diagnosis, which could lead to improved outcomes for patients and their families.

Loss of heterozygosity at 19p13.2 and 2q21 in tumours from familial clusters of non-medullary thyroid carcinoma

Linkage studies have identified susceptibility loci for familial nonmedullary thyroid cancer (FNMTC), with and without cell oxyphilia, at chromosomal regions 19p13.2 and 2q21. There are few genetic analyses of FNMTC tumours reported at the present time and the eventual gene involved was not identified yet. The aim of this study was to assess the occurrence of loss of heterozygosity (LOH) at these loci in the tumours from familial clusters of NMTC. We have analysed LOH in 14 tumours from 9 two-case familial clusters of NMTC. Using paired blood (normal) and tumour DNA samples, we have genotyped ten microsatellite and one SNP markers throughout 19p13.2 and fourteen microsatellite markers at 2q21. Overall, eight (57%) and two (14%) out of the fourteen tumours analysed exhibited LOH at 19p13.2 and 2q21, respectively. In two families (22%), LOH for the same markers was demonstrable in the tumours of the two members of the same family. In one family (11%) LOH was demonstrable at both loci analysed. In four two-case familial clusters (44%), LOH at the 19p13.2 locus was found in only one of the tumour cases analysed. Detailed haplotype analysis showed that, in two families (22%), the pattern of LOH in tumours was consistent with selective retention of the haplotype shared by affected members. In the remaining cases, it was consistent with random allelic losses. In conclusion, we report the finding of LOH at the 19p13.2 and 2q21 loci in tumours from familial clusters of NMTC, providing evidence that inactivation of putative genes in these regions, acting as tumour-suppressors, may be involved in the development of tumours in the context of FNMTC.

Increasing incidence of thyroid cancer in Basilicata: an Italian study

OBJECTIVE

In recent years many authors have reported an increase in thyroid cancer (TC) incidence in several countries. The cause of such phenomenon remains unclear.

DESIGN

This study was designed to estimate the incidence of TC in Basilicata, the smallest region of Southern Italy with a population of 596,546 people, between 2001 and 2004.

MAIN OUTCOME

A total of 302 cases of TC were identified. The annual incidence of TC changed over the years, from 10.0 per 100,000 people in 2001 to 15.7 per 100,000 people in 2004. The number of new TC cases per 100,000 people increased an average of 16% per yr. Median age at diagnosis was 49 yr. The most frequent histotype was papillary TC (PTC) (73.2%). In 20 (6.6%) patients with PTC, we identified at least one first-degree relative affected by differentiated TC.

CONCLUSIONS

The present study shows a high incidence of sporadic and familial non-medullary TC in Basilicata. The reason for this finding may be related to several factors discussed in the paper. Further studies evaluating the trends in the incidence of TC in Basilicata in the future could provide some answers for the potential pathogenetic hypothesis.

Inherited aspects of papillary thyroid carcinoma

The presence of papillary carcinoma of the thyroid in multiple generations of one kindred is a statistical impossibility as an occurrence of chance. However, traditional and molecular genetic analyses to date have failed to support the notion of a single gene mutation or identify one, in distinct contrast to medullary carcinoma of the thyroid. Findings to date, outside of distinct multicancer syndromes, suggest the interplay of inherited susceptibility and other factors, such as environmental exposures. It is possible that the main identifiable genetic risk factors at this time are the presence of multinodular goiter or Hashimoto's thyroiditis within the family.

Familial nonmedullary thyroid carcinoma

BACKGROUND

Nonmedullary thyroid carcinomas (NMTCs) originate from the thyroid epithelial cells and, until recently, were thought to arise sporadically without an inherited genetic predisposition. However, evidence of a familial predisposition to NMTC is accumulating.

METHODS

This review addresses the strengths, weaknesses, and clinical implications of the observations indicating an inherited genetic predisposition to NMTC. These observations include epidemiologic studies, descriptions of large kindreds, and genetic analyses.

RESULTS

Familial NMTC (FNMTC) may be caused by an inherited genetic predisposition and can be divided into two groups. The first group has an increased prevalence of NMTC within a familial cancer syndrome with a preponderance of nonthyroidal tumors. In the second group the predominant neoplasm is NMTC, although other neoplasms may occur with increased frequency. These disorders are the focus of this review.

CONCLUSIONS

A family history in NMTC patients should be directed at detecting those familial tumor syndromes with a preponderance of NMTC as well as those familial tumor syndromes enriched in NMTC but with a preponderance of nonthyroidal tumors. Since the recurrence rates may be greater in FNMTC than in sporadic NMTC, careful monitoring is indicated for affected individuals. The advantages and disadvantages of screening asymptomatic members of FNMTC kindreds with thyroid ultrasound are discussed, and the final decision is deferred to the treating physicians and their patients. It is hoped that positional cloning research will identify the FNMTC susceptibility genes.

Familial papillary thyroid carcinoma

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

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.

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

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

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 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.

Gender effects in familial cancer

Very limited data are available on sex ratios in familial cancer. Such data would be valuable in the assessment of sex chromosome effects and of interactions between background and familial rates. We used the nationwide Swedish Family-Cancer Database on 10.2 million individuals and over 1 million neoplasms to analyze familial risks for male and female offspring by paternal and maternal concordant cancer. Sex ratios for familial cancer were derived for cancer at 15 sites shared by men and women. At 14 sites the sex ratio (male/female) for familial relative risk ranged between 0.78 and 1.41, with no evidence of sex preference, suggesting that sex chromosomes do not contribute to a noticeable extent to familial risks. Furthermore, in cancers where the background incidence varied extensively by sex, such as bladder cancer (sex ratio 2.82) and nonthyroid endocrine tumors (0.65), the familial effect was proportionate to the background incidence and the familial sex ratio was close to unity. In thyroid cancer, the familial sex ratio was 2.48 (1.54-3.98) and the background incidence ratio was 0.31. This was the first evidence of an inverse sex ratio in primary cancer, i.e., higher familial risk in the gender of low background risk. The high familial ratio, 2.85 (95% CI: 1.35-6.03), was due to thyroid adenocarcinoma, encompassing both papillary and follicular types.

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-Hodgkin's 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-Hodgkin's 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.

Environmental and heritable causes of cancer among 9.6 million individuals in the Swedish Family-Cancer Database

The genetic and environmental components in 15 common cancers were estimated using the nationwide Swedish Family-Cancer Database. Tetrachoric correlations were used to describe similarity in cancer liability among family members. Structural equation modeling was used to derive estimates of the importance of genetic and environmental effects. Statistically significant estimates of proportion of cancer susceptibility, accounted for by genetic effects, were obtained for all studied cancers except for leukemia. The estimate was highest in thyroid cancer (53%), followed by tumors at endocrine glands (28%), testis (25%), breast (25%), cervix (22%), melanoma (21%), colon (13%), nervous system (12%), rectum (12%), non-Hodgkin lymphoma (10%), lung (8%), kidney (8%), urinary bladder (7%), stomach (1%) and leukemia (1%). The estimates of shared environmental effects ranged from 0% (cervix) to 15% (stomach). The childhood shared environmental effects were most important in testicular cancer (17%), stomach cancer (13%) and cervix in situ (13%). Our results indicate that environment has a principal causative role in cancer at all studied sites except for thyroid. The relatively large effect of heritability in cancer at some sites, on the other hand, indicates that even though susceptibility genes have been described at many cancer sites, they are likely to explain only part of the genetic effects.

Characteristics of follicular cell-derived thyroid carcinomas occurring after external radiation exposure: results of a case control study nested in a cohort

Radiation exposure is the only well-established risk factor for follicular cell-derived thyroid carcinoma. To compare the clinical characteristics and outcome of thyroid carcinoma in patients with and without a history of radiation exposure, we performed a case control study nested in a cohort of 2,196 patients treated for a papillary or a follicular thyroid cancer at the Institut Gustave Roussy. The study was performed on 91 cases (71% females) and their 273 controls matched for gender, age at thyroid cancer diagnosis (+/-3 years), and period of initial thyroid cancer treatment (+/-6 years). More than 85% of the cases have been first exposed to external radiation before the age of 30 years. Thyroid cancers were more frequently multifocal in cases than in controls (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.3-4.8), and local residual tumor was more frequently observed in cases, but the other clinical features did not differ overall. Female cases with a history of radiation exposure more frequently had a tumor of follicular histology than female controls (OR = 2.7, 95% CI: 1.1-6.5), and conversely the frequency of follicular histology was similar in male cases and in male controls (OR = 0.3, 95% CI: 0.1-1.4). The risks of recurrence and of thyroid cancer related death were similar in cases and in controls.

Familial colorectal adenocarcinoma from the Swedish Family-Cancer Database

Familial risks for colorectal (CRC) adenocarcinoma were characterized from the Swedish Family-Cancer Database covering 9.6 million individuals, whose family relationships and cancers were obtained from registered sources, not sensitive to reporting or ascertainment bias. Cancer cases were retrieved from the Swedish Cancer Registry from years 1958-96. Standardized incidence ratios (SIRs) were calculated based on gender-, age-, period- and tumor type specific rates. A total of 4,794 and 67,925 CRCs were recorded in offspring and parents, respectively. For colon and rectal adenocarcinoma, the SIRs in offspring were 2.28 and 1.68 by parental CRC adenocarcinoma, giving attributable proportions of 6.45 and 3.31%, respectively. The SIR of CRC was over 10 when both offspring and parents were diagnosed at a young age. The risk for parental CRC adenocarcinoma was over 100 when 2 or more children were affected. The risk in siblings was also very high when a parent was affected. The familial cancer sites that associated with CRC were those typical of hereditary nonpolyposis colorectal cancer (HNPCC). This is the largest study published on familial CRC and the only one reporting specifically on adenocarcinoma. The data suggest that HNPCC is the largest single disease entity among CRCs, probably accounting for less than 50% of familial CRC. Other familial components appear heterogeneous, characterized by incomplete penetrance, recessive mode of inheritance and few associated tumor sites.

Increased risk for nonmedullary thyroid cancer in the first degree relatives of prevalent cases of nonmedullary thyroid cancer: a hospital-based study

The genetic basis for nonmedullary forms of thyroid cancer (NMTC) is less well established than that of medullary thyroid cancer. However, epidemiological and family studies suggest that a proportion of NMTC may be due to inherited predisposition. To estimate the familial risk of thyroid cancer, we conducted a hospital-based case-control study at the Princess Margaret Hospital in Toronto, Ontario, Canada, and at 2 university hospitals in Montréal, Québec, Canada. We obtained pedigrees from 339 unselected patients diagnosed with NMTC and from 319 unaffected ethnically matched controls. Family histories of cancer were obtained from the cases and controls for 3292 first degree relatives of cases and controls. Seventeen cases (5.0%) and 2 controls (0.6%) reported at least one first degree relative with thyroid cancer. In relatives of patients with thyroid cancer, the incidence of any type of cancer (including NMTC) was 38% higher than in relatives of controls (incidence rate ratio, 1.4; 95% confidence interval, 1.1-1.7). The relative risk for thyroid cancer was 10-fold higher in relatives of cancer patients than in controls (incidence rate ratio, 10.3; 95% confidence interval, 2.2-47.6). Our findings suggest that hereditary or other familial factors are important in a small proportion of NMTC. Molecular studies are needed to determine the genetic basis of cancer susceptibility in these families.

Second primary neoplasms after 19281 endocrine gland tumours: aetiological links?

The nationwide Swedish Family-Cancer Database of 9.6 million individuals was used to analyse the development of second neoplasia after 6909 thyroid and 12697 other endocrine tumours. Tumour cases were retrieved from the Swedish Cancer Registry from 1958 to 1996. The risk of a second endocrine tumour was markedly increased compared with first endocrine tumour; e.g. the standardised incidence ratios (SIRs) were well over 10 for adrenal tumours after thyroid cancer, and vice versa. Familial risks were higher for the development of second compared with first neoplasms, and the SIRs for men were usually higher than those for women. Many increases between different endocrine glands can probably be ascribed to known cancer syndromes. Even cancers at some other sites were increased after the development of primary endocrine tumours. Notably, small intestinal carcinoids were increased after thyroid and other endocrine tumours, and brain menigiomas were increased after parathyroid and pituitary adenomas. These novel associations suggest shared risk factors for these sites. However, many endocrine tumours are benign and the diagnosis of the first tumour may increase the likelihood of a second diagnosis.

Cohort study of thyroid cancer in a San Francisco Bay area population

Using data from a large health plan, we performed a cohort study of thyroid cancer among 204,964 persons (aged 10--89 at baseline in 1964--1973, 54% female) followed for a median of 20 years. There were 196 incident thyroid cancers (73 in men, 123 in women). Risk was independently and positively related to female gender [relative risk (RR) = 1.56, 95% confidence interval (CI) = 1.12--2.19], Asian race (RR = 2.86, 95% CI = 1.76--4.65), completed college or post-graduate education (RR = 1.76, 95% CI = 1.20--2.59), history of goiter (RR = 3.36, 95% CI = 1.82--6.20), radiation of the neck region (RR = 2.33, 95% CI = 1.28--4.23) and family history of thyroid disease (RR = 2.18, 95% CI = 1.17--4.05). An inverse association was found for black race (RR = 0.55, 95% CI = 0.33--0.91). Cigarette smoking, alcohol consumption, personal history of hyperthyroidism, hypothyroidism, overweight or obesity, weight gain since age 20, height, occupational exposures, reproductive factors, oral contraceptives and hormone use did not show statistically significant relations to thyroid cancer. These results provide further evidence for a role of female gender, radiation, goiter, Asian race, high educational attainment and family history of thyroid disease in the etiology of thyroid cancer.

Cancer risks to spouses and offspring in the Family-Cancer Database

It is generally accepted that cancer is caused by environmental and inherited factors but these are only partially identified. Family studies can be informative but they do not separate shared lifestyles and genes. We estimate familial risks for concordant cancers between spouses in common cancers of both sexes in order to quantify cancer risks from the shared environment. The risks are compared to those seen between parents and offspring in order to estimate the inherited component. The nation-wide Family-Cancer Database was used as the source of family and cancer data. Standardized incidence ratios (SIRs) were calculated for concordant cancer in offspring by parental cancer and in spouses. Among the 23 cancer sites considered, all but two showed an increased SIR for offspring by father or mother. Only two sites, stomach and lung, showed an increase in SIR of concordant cancer among spouses. Additionally, pancreatic cancer and melanoma were increased in couples where at least one spouse was diagnosed before age 50. If both spouses presented melanoma before age 40, SIR was 3.82 for husbands. SIRs of colon, renal, and skin (squamous cell) cancers were unchanged by spouses' concordant cancer. Shared lifestyle among spouses seems to explain only a small proportion of cancer susceptibility. Because lifestyles are likely to differ more between parents and offspring than between spouses, familial cancer risks between parents and offspring are likely to be more due to heritable rather than environmental effects.

Genetic epidemiology of multistage carcinogenesis

It is commonly believed that cancer is a multistage, polygenic disease. Even though conceptually appealing, the evidence supporting the multistage theory remains limited. Most known tumor suppresser genes are associated with monogenic dominant cancers following a two-hit pathway. We review results from a recent twin study on 90000 individuals that give support to the multistage theory. Statistically significant heritability estimates were shown for cancers of the colorectum (35%), breast (27%), and prostate (42%). These estimates are much higher than those obtained from family studies in which parents and offspring, or sibs are compared. The difference can be accounted for by the involvement of many genes. A polygenic cancer would show small effects in family studies but large effects in twin studies. We present calculations on the decrease in familial risks when the number of genes involved increases or when the penetrance decreases. We test the apparent number of stages involved in the main cancers from the Swedish Family-Cancer Database. The logarithms of the slopes suggest large differences in the apparent numbers of mutations involved in different cancers. The number of mutations required appears to be less in familial breast cancer compared to sporadic breast cancer. Study designs for gene identification should be revised to accommodate polygenic cancers.