Long-Term Clinical Outcome in Familial and Sporadic Papillary Thyroid Carcinoma

FAMILIAL NON-MEDULLARY THYROID CARCINOMA

BACKGROUND

Familial non-medullary thyroid carcinoma (FNMTC) is defined as cancer developing in two or more first-degree relatives if predisposing factors, for example, radiation, are absent. The disease can be either syndromic, when it is a component of complex genetic syndromes, or non-syndromic (95% cases). The genetic basis of non-syndromic FNMTC is unknown; the clinical behavior of tumorsis unclear and, at times, contradictory.

AIM

To analyze clinical manifestations of FNMTC and compare them with the data for sporadic papillary thyroid carcinomas in patients of the same age groups.

MATERIALS AND METHODS

We examined 22 patients (a "parents" group and a "children" group) suffering from the non-syndromic FNMTC. For comparison, two groups of sporadic papillary carcinomas patients of the same age were drawn up("adult" and "young"). We analyzed tumor size and frequency of the distributionby the categoryof TNM system, invasiveness, multifocality, metastases to lymph nodes, type and extent of surgical and radioiodine treatment, and prognosis according to the MACIS criterion.

RESULTS

Whether sporadic or familial, the tumor size, metastatic potential, and invasive potential are higher in young people, asalready known. There was no significant difference between the "parents" and "adult" groups of patients in terms of tumor parameters. One exception was the higher frequency of multifocal tumors in the FNMTC patients. Meanwhile, compared to the "young" sporadic papillary carcinomas patients, the FNMTC "children" had a higher frequency of T2 tumors, metastasizing (N1a-N1ab), and multifocal tumors, but a lower frequency of carcinomas with intrathyroidal invasions.In the FNMTC "children" compared to FNMTC "parents" was a higher frequency of T2 tumors, metastasizing carcinomas, and tumors with capsular invasion.

CONCLUSION

FNMTC carcinomas are more aggressive than sporadic ones, especially in patients who are first-degree relatives in a family with parents already diagnosed with the disease.

Genetic susceptibility to hereditary non-medullary thyroid cancer

Non-medullary thyroid cancer (NMTC) is the most common type of thyroid cancer. With the increasing incidence of NMTC in recent years, the familial form of the disease has also become more common than previously reported, accounting for 5-15% of NMTC cases. Familial NMTC is further classified as non-syndromic and the less common syndromic FNMTC. Although syndromic NMTC has well-known genetic risk factors, the gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified. To date, several candidate genes have been identified as susceptibility genes in hereditary NMTC. This review summarizes genetic predisposition to non-medullary thyroid cancer and expands on the role of genetic variants in thyroid cancer tumorigenesis and the level of penetrance of NMTC-susceptibility genes.

Identification of NID1 as a novel candidate susceptibility gene for familial non-medullary thyroid carcinoma using whole-exome sequencing

The genetics underlying non-syndromic familial non-medullary thyroid carcinoma (FNMTC) is still poorly understood. To identify susceptibility genes for FNMTC, we performed whole-exome sequencing (WES) in a Brazilian family affected by papillary thyroid carcinoma (PTC) in three consecutive generations. WES was performed in four affected and two unaffected family members. Manual inspection in over 100 previously reported susceptibility genes for FNMTC showed that no variants in known genes co-segregated with disease phenotype in this family. Novel candidate genes were investigated using PhenoDB and filtered using Genome Aggregation (gnomAD) and Online Archive of Brazilian Mutations (ABraOM) population databases. The missense variant p.Ile657Met in the NID1 gene was the only variant that co-segregated with the disease, while absent in unaffected family members and controls. The allele frequency for this variant was <0.0001 in the gnomAD and ABbraOM databases. In silico analysis predicted the variant to be deleterious or likely damaging to the protein function. Somatic mutations in NID1 gene were found in nearly 500 cases of different cancer subtypes in the intOGen platform. Immunohistochemistry analysis showed NID1 expression in PTC cells, while it was absent in normal thyroid tissue. Our findings were corroborated using data from the TCGA cohort. Moreover, higher expression of NID1 was associated with higher likelihood of relapse after treatment and N1b disease in PTCs from the TCGA cohort. Although replication studies are needed to better understand the role of this variant in the FNMTC susceptibility, the NID1 variant (c.1971T>G) identified in this study fulfills several criteria that suggest it as a new FNMTC predisposing gene.

DICER1 tumor predisposition syndrome: an evolving story initiated with the pleuropulmonary blastoma

DICER1 syndrome (OMIM 606241, 601200) is a rare autosomal dominant familial tumor predisposition disorder with a heterozygous DICER1 germline mutation. The most common tumor seen clinically is the pleuropulmonary blastoma (PPB), a lung neoplasm of early childhood which is classified on its morphologic features into four types (IR, I, II and III) with tumor progression over time within the first 4-5 years of life from the prognostically favorable cystic type I to the unfavorable solid type III. Following the initial report of PPB, its association with other cystic neoplasms was demonstrated in family studies. The detection of the germline mutation in DICER1 provided the opportunity to identify and continue to recognize a number seemingly unrelated extrapulmonary neoplasms: Sertoli-Leydig cell tumor, gynandroblastoma, embryonal rhabdomyosarcomas of the cervix and other sites, multinodular goiter, differentiated and poorly differentiated thyroid carcinoma, cervical-thyroid teratoma, cystic nephroma-anaplastic sarcoma of kidney, nasal chondromesenchymal hamartoma, intestinal juvenile-like hamartomatous polyp, ciliary body medulloepithelioma, pituitary blastoma, pineoblastoma, primary central nervous system sarcoma, embryonal tumor with multilayered rosettes-like cerebellar tumor, PPB-like peritoneal sarcoma, DICER1-associated presacral malignant teratoid neoplasm and other non-neoplastic associations. Each of these neoplasms is characterized by a second somatic mutation in DICER1. In this review, we have summarized the salient clinicopathologic aspects of these tumors whose histopathologic features have several overlapping morphologic attributes particularly the primitive mesenchyme often with rhabdomyoblastic and chondroid differentiation and an uncommitted spindle cell pattern. Several of these tumors have an initial cystic stage from which there is progression to a high grade, complex patterned neoplasm. These pathologic findings in the appropriate clinical setting should serve to alert the pathologist to the possibility of a DICER1-associated neoplasm and initiate appropriate testing on the neoplasm and to alert the clinician about the concern for a DICER1 mutation.

Familial non-medullary thyroid cancer: a critical review

BACKGROUND

Familial non-medullary thyroid carcinoma (FNMTC), mainly of papillary histotype (FPTC), is defined by the presence of the disease in two or more first-degree relatives in the absence of other known familial syndromes. With the increasing incidence of PTC in the recent years, the familial form of the disease has also become more common than previously reported and constitutes nearly 10% of all thyroid cancers. Many aspects of FNMTC are debated, concerning both clinical and genetic aspects. Several studies reported that, in comparison with sporadic PTCs, FPTCs are more aggressive at disease presentation, while other authors reported no differences in the clinical behavior of sporadic and familial PTCs. For this reason, recent guidelines do not recommend screening of family members of patients with diagnosis of differentiated thyroid cancer (DTC). FNMTC is described as a polygenic disorder associated with multiple low- to moderate-penetrance susceptibility genes and incomplete penetrance. At the moment, the genetic factors contributing to the development of FNMTC remain poorly understood, though many putative genes have been proposed in the recent years.

PURPOSE

Based on current literature and our experience with FNMTC, in this review, we critically discussed the most relevant controversies, including its definition, the genetic background and some clinical aspects as screening and treatment.

Inherited Follicular Epithelial-Derived Thyroid Carcinomas: From Molecular Biology to Histological Correlates

Cancer derived from thyroid follicular epithelial cells is common; it represents the most common endocrine malignancy. The molecular features of sporadic tumors have been clarified in the past decade. However the incidence of familial disease has not been emphasized and is often overlooked in routine practice. A careful clinical documentation of family history or familial syndromes that can be associated with thyroid disease can help identify germline susceptibility-driven thyroid neoplasia. In this review, we summarize a large body of information about both syndromic and non-syndromic familial thyroid carcinomas. A significant number of patients with inherited non-medullary thyroid carcinomas manifest disease that appears to be sporadic disease even in some syndromic cases. The cytomorphology of the tumor(s), molecular immunohistochemistry, the findings in the non-tumorous thyroid parenchyma and other associated lesions may provide insight into the underlying syndromic disorder. However, the increasing evidence of familial predisposition to non-syndromic thyroid cancers is raising questions about the importance of genetics and epigenetics. What appears to be "sporadic" is becoming less often truly so and more often an opportunity to identify and understand novel genetic variants that underlie tumorigenesis. Pathologists must be aware of the unusual morphologic features that should prompt germline screening. Therefore, recognition of harbingers of specific germline susceptibility syndromes can assist in providing information to facilitate early detection to prevent aggressive disease.