The possible association between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) is a still debated issue. We analyzed the frequency of PTC, TSH levels and thyroid autoantibodies (TAb) in 13 738 patients (9824 untreated and 3914 under l-thyroxine, l-T4). Patients with nodular-HT (n=1593) had high titer of TAb and/or hypothyroidism. Patients with nodular goiter (NG) were subdivided in TAb−NG (n=8812) with undetectable TAb and TAb+NG (n=3395) with positive TAb. Among untreated patients, those with nodular-HT showed higher frequency of PTC (9.4%) compared with both TAb−NG (6.4%; P=0.002) and TAb+NG (6.5%; P=0.009) and presented also higher serum TSH (median 1.30 vs 0.71 μU/ml, P<0.001 and 0.70 μU/ml, P<0.001 respectively). Independently of clinical diagnosis, patients with high titer of TAb showed a higher frequency of PTC (9.3%) compared to patients with low titer (6.8%, P<0.001) or negative TAb (6.3%, P<0.001) and presented also higher serum TSH (median 1.16 vs 0.75 μU/ml, P<0.001 and 0.72 μU/ml, P<0.001 respectively). PTC frequency was strongly related with serum TSH (odds ratio (OR)=1.111), slightly related with anti-thyroglobulin antibodies (OR=1.001), and unrelated with anti-thyroperoxidase antibodies. In the l-T4-treated group, when only patients with serum TSH levels below the median value (0.90 μU/ml) were considered, no significant difference in PTC frequency was found between nodular-HT, TAb−NG and TAb+NG. In conclusion, the frequency of PTC is significantly higher in nodular-HT than in NG and is associated with increased levels of serum TSH. Treatment with l-T4 reduces TSH levels and decreases the occurrence of clinically detectable PTC.
E Fiore, T Rago, F Latrofa, M A Provenzale, P Piaggi, A Delitala, M Scutari, F Basolo, G Di Coscio, L Grasso, A Pinchera and P Vitti
F Cetani, E Pardi, E Ambrogini, P Viacava, S Borsari, M Lemmi, L Cianferotti, P Miccoli, A Pinchera, A Arnold and C Marcocci
Early onset of primary hyperparathyroidism (PHPT) and multiglandular involvement suggest a familial form in which germline mutation of a PHPT-related gene(s) and a somatic event at the same locus can be often demonstrated. We investigated the involvement of multiple endocrine neoplasia type 1 (MEN1) and HRPT2 genes in a 39-year-old man with recurrent PHPT. PHPT was firstly diagnosed at the age of 21 and the patient had two recurrences separated by extended periods of normocalcemia. This unusual history prompted us to investigate other family members and study the MEN1 and HRPT2 genes. An HRPT2 germline missense mutation in exon 3 (R91P) was found in the index case, which was associated with different HRPT2 somatic alterations in each of the three examined parathyroid tumors. These findings are consistent with Knudson’s ‘two hit’ concept of biallelic inactivation of classical tumor suppressor genes. Screening of 15 asymptomatic relatives was negative for the R91P germline mutation. All the three abnormal parathyroid specimens showed cystic features at histology and were negative for parafibromin immunostaining. In one specimen, diffuse parafibromin staining was evident in a rim of normal parathyroid tissue surrounding the adenomatous lesion. Our study shows that different somatic genetic events at the HRPT2 locus are responsible for the asynchronous occurrence of multiple adenomas in a patient carrying an HRPT2 germline mutation. The finding of diffuse parafibromin staining in a rim of normal parathyroid tissue, but not in the contiguous adenomatous lesion, reinforces the concept that loss of parafibromin expression is responsible for the development of parathyroid tumors in this setting.
E Fiore, T Rago, M A Provenzale, M Scutari, C Ugolini, F Basolo, G Di Coscio, P Miccoli, L Grasso, A Pinchera and P Vitti
The risk of papillary thyroid cancer (PTC) is related to serum TSH, and the development of thyroid autonomy by reducing TSH levels decreases the frequency of PTC in patients with nodular goiter. Our aim was to investigate the effect of l-thyroxine (l-T4) on the frequency of PTC diagnosed by cytology in a large series of patients with nodular goiter untreated (n=20 055) or treated with l-T4 (n=7859). l-T4-treated patients with respect to untreated patients presented significantly lower serum TSH (median, interquartile range: 0.30 μU/ml, 0.08–0.62 μU/ml versus 0.70 μU/ml, 0.38–1.14 μU/ml; P<0.0001) and prevalence of PTC (3.2 vs 5.1%; P<0.0001). The frequency of PTC was closely related to serum TSH, with it being lowest in patients with TSH below the normal range (<0.4 μU/ml; 189/10 059, 1.9%) and highest in patients with TSH above the normal range (>3.4 μU/ml; 21/127, 16.5%), also showing a progressive increase from the lower to the upper quartile of normal range. A significantly higher proportion of l-T4-treated patients (6650/7859, 84.6%) had serum TSH below the median (0.90 μU/ml) with respect to untreated patients (12 599/20 055, 62.8%; χ 2 P value <0.0001), with it being included in the range of TSH associated with a lower frequency of PTC. The relationship between serum TSH and frequency of PTC was unrelated to the type of nodularity (solitary versus multinodular) and was not age dependent. In conclusion, patients with nodular goiter, treatment with l-T4 is responsible for the reduction of serum TSH and is associated with a decreased frequency of PTC.
F Cetani, E Pardi, C Banti, P Collecchi, P Viacava, S Borsari, G Fanelli, A G Naccarato, F Saponaro, P Berti, P Miccoli, A Pinchera and C Marcocci
Aberrant accumulation of β-catenin has been found in various types of human tumors. The aim of this study was to evaluate whether Wnt/β-catenin signaling is activated in parathyroid carcinomas and adenomas. We studied 154 parathyroid tumors (18 carcinomas (13 with distant metastases), six atypical adenomas, and 130 adenomas). Three normal parathyroid tissues were used as control. Direct sequencing of exon 3 of the CTNNB1 gene showed absence of stabilizing mutations in all the tumors. Immunostaining of β-catenin was performed in all carcinomas and in 66 adenomas (including three atypical). Normal parathyroid showed a homogeneous distinct outer cell membrane staining in the majority of cells and no nuclear staining. A weak cytoplasmic staining was observed in one case. All tumors showed negative nuclear staining. With the exception of one carcinoma, which had a negative membrane staining, all other samples showed a membrane staining which was similar to that of the normal parathyroid. β-Catenin expression was heterogeneous with a range of positive cells between 5 and 80%, independently of tumor type. Our results suggest that the Wnt/β-catenin signaling pathway is not involved in the development of parathyroid carcinomas and adenomas.
E Fiore, T Rago, M A Provenzale, M Scutari, C Ugolini, F Basolo, G Di Coscio, P Berti, L Grasso, R Elisei, A Pinchera and P Vitti
Higher TSH values, even within normal ranges, have been associated with a greater risk of thyroid malignancy. The relationship between TSH and papillary thyroid cancer (PTC) has been analyzed in 10 178 patients submitted to fine needle aspiration of thyroid nodules with a cytology of PTC (n=497) or benign thyroid nodular disease (BTND, n=9681). In 942 patients, submitted to surgery (521 from BTND and 421 from PTC), the histological diagnosis confirmed an elevated specificity (99.6%) and sensitivity (98.1%) of cytology. TSH levels were significantly higher in PTC than in BTND both in the cytological and histological series and also in patients with a clinical diagnosis of multinodular goiter (MNG) and single/isolate nodule (S/I). A significant age-dependent development of thyroid autonomy (TSH <0.4 μU/ml) was observed in patients with benign thyroid disease, but not in those with PTC, diagnosed both on cytology and histology. In patients with MNG, the frequency of thyroid autonomy was higher and the risk of PTC was lower compared to those with S/I. In all patients, the presence of thyroid auto-antibodies (TAb) was associated with a significant increase of TSH. However, both in TAb positive and TAb negative patients TSH levels were significantly higher in PTC than in BTND. Our data confirm a direct relationship between TSH levels and risk of PTC in patients with nodular thyroid diseases. Thyroid autonomy conceivably protects against the risk of PTC, while thyroid autoimmunity does not play a significant role.
B Cosci, A Vivaldi, C Romei, F Gemignani, S Landi, R Ciampi, A Tacito, E Molinaro, L Agate, V Bottici, V Cappagli, D Viola, P Piaggi, P Vitti, A Pinchera and R Elisei
Germline and somatic RET oncogene mutations are found in 98% hereditary and 40% sporadic medullary thyroid carcinomas. Our aim was to analyse by in silico and in vitro assays the transforming activity of six rare RET mutations (T338I, V648I, M918V, A883T, S904F and M848T). Six known RET mutations were used as controls. The in silico analysis showed the highest score value (i.e. 65) for S904F, M848T, M918T and C634R, whereas L790F, G691S, T338I and V648I had 0 score. Intermediate score values were obtained by A883T (score=55), M918V, V804M and Y791F (score=15). The in vitro focus formation assay showed that cells transfected with S904F, M918T, M848T or C634R generated the largest number of focus formation units (FFU). Intermediate numbers of FFU were observed in cells transfected with M918V, V804M, Y791F or A883T, while cells transfected with L790F, G691S, T338I or V648I showed a number of FFU similar to control cells. A positive correlation between the in silico score and in vitro FFU was found (P=0.0005). Only cells transfected with M918T or C634R grew faster and generated higher number of colonies in soft agar than control cells. However, the cells that were transfected with V804M produced an intermediate number of colonies. In conclusion, two of the six rare RET mutations, S904F and M848T possessed a relatively high transforming activity but a low aggressiveness; the other four mutations T338I, V648I, M918V and A883T were low or non-transforming, and their ability to induce tumoural transformation might be related to particular genetic conditions.
L Fugazzola, E Puxeddu, N Avenia, C Romei, V Cirello, A Cavaliere, P Faviana, D Mannavola, S Moretti, S Rossi, M Sculli, V Bottici, P Beck-Peccoz, F Pacini, A Pinchera, F Santeusanio and R Elisei
Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype–phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of χ2/Fisher’s exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF V600E mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF V600E was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF V600E and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF V600E (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38–40%. Furthermore, B-RAF V600E was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.