Targeted treatment of differentiated and medullary thyroid cancer

Prognostic Factors for Differentiated Thyroid Carcinoma and Review of the Literature

Objective

Prognostic factors of differentiated thyroid carcinoma (DTC) are analyzed to justify the diagnostic and therapeutic modalities of DTC in current practice.

Methods

Patients undergoing curative resection for histologically diagnosed DTC (n = 150) were consecutively enrolled, and the clinical and pathological data were retrospectively reviewed.

Results

The DTC patient cohort consisted of 113 females (75.3%; mean age at the time of onset, 40.1 ± 12.0 yr) and 37 males (24.7%; 47.5 ± 16.2 yr). The pathological types of DTC included papillary thyroid carcinoma (n = 131, 87.3%) and follicular thyroid carcinoma (n = 19, 12.7%). The follow-up period ranged from 4.2 to 31 years, in which period 140 (93.3%) patients survived, 30 (20.0%) patients relapsed, and 10 (6.7%) patients died of DTC. Surgical procedures used for the curative resection consisted of near-total or subtotal thyroidectomy (n = 83, 55.3%), partial thyroidectomy (n = 64, 42.7%) and total thyroidectomy (n = 3, 2.0%). Out of those patients undergoing concomitant lymph node dissection (n = 63, 42.0%), 45 patients (71.4%) had detectable lymph node metastases. Postoperatively, 12 patients (8.0%) received external beam radiotherapy, 16 patients (10.7%) received chemotherapy, 37 patients (24.7%) received 131I therapy, and 66 patients (44.0%) received additional long-term L-T4 or thyroid hormone treatment. Age of onset, tumor size at initial visit, and rate of early metastasis showed statistically significant differences between the mortality group and the survival group (P <0.05) and between the recurrence group and the recurrence-free group (P <0.05).

Conclusions

Age, tumor size at initial visit, and early metastasis are prognostic factors for DTC, requiring a stratified management in clinical practice.

Evaluation of expression and function of vascular endothelial growth factor receptor 2, platelet derived growth factor receptors-alpha and -beta, KIT, and RET in canine apocrine gland anal sac adenocarcinoma and thyroid carcinoma

Background

Toceranib phosphate (Palladia) has a reported objective response rate of 25% in both canine apocrine gland anal sac adenocarcinoma (AGASACA) and thyroid carcinoma (TC), with stable disease occurring in an additional 50-60% of dogs. The basis for the observed responses to toceranib is not known. The purpose of this study was to evaluate AGASACA and TC samples for the expression and activation of VEGFR2, PDGFRα, PDGFRβ, KIT and RET to assess whether dysregulation of these receptor tyrosine kinases (RTKs) may contribute to the biologic activity of toceranib.

Results

mRNA for VEGFR2, PDGFRα/β, KIT and RET was detected in all AGASACA samples. mRNA for VEGFR2, PDGFRα/β, and KIT was detected in all TC samples, while mRNA for RET was amplified in 10/15 samples. No phosphorylation of VEGFR2, PDGFRα/β, or KIT was observed on the arrays. However, phosphorylation of RET was detected in 54% of the primary AGASACA and 20% of TC. VEGFR2 was expressed in 19/24 primary and 6/10 metastatic AGASACA and 6/15 TC samples. KIT was present in 8/24 primary and 3/10 metastatic AGASACA and 9/15 TC samples. PDGFRα expression was noted in all tumor samples. In contrast PDGFRβ expression was found in only a few tumor samples but was evident in the stroma of all tumor specimens.

Conclusions

Known targets of toceranib are expressed in both AGASAC and TC. Given the observed expression of VEGFR and PDGFRα/β and phosphorylation of RET, these RTKs merit investigation as to their roles in the biology of AGSACA and TC and their contribution to toceranib’s activity.

Increased T-allele frequency of 677 C>T polymorphism in the methylenetetrahydrofolate reductase gene in differentiated thyroid carcinoma

BACKGROUND

Epigenetic alterations in the global DNA methylation status may be associated with an increased risk of some cancer types in humans. The methylenetetrahydrofolate reductase (MTHFR) gene is involved in folic acid metabolism and plays an essential role in inherited DNA methylation profiles. The common 677 C>T and 1298 A>C polymorphisms in the MTHFR gene cause the production of a thermolabile enzyme with reduced function and, eventually, genomic DNA hypomethylation. The current preliminary study was designed to determine the association between germ-line polymorphism in the MTHFR gene and differentiated thyroid carcinoma (DTC).

METHODS

In the current case-control study of 60 thyroid carcinomas (TC); 45 papillary TC, 9 follicular TC, and 6 DTC of an uncertain malignant potential were examined. Genomic DNA was extracted from peripheral blood with EDTA, genotyped by a multiplex real-time polymerase chain reaction.

RESULTS

An elevated 2.33-fold risk was observed for DTC in individuals with the 677TT genotype when compared with the control group (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.03-3.58). Current DTC patients showed similar results as a control group for the 1298 A>C allele. No significant risk was detected for the homozygous 1298CC genotype (CC vs. AA or AC) (OR: 1.30, 95% CI: 0.73-2.29).

CONCLUSION

The current results are supportive of the hypothesis that the homozygous MTHFR 677TT genotype increases the risk factor of developing thyroid cancer, and further large-scale studies are needed to validate this association.