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.
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
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.