McIver, Bryan

Abstract Anaplastic thyroid carcinoma (ATC) is a highly aggressive form of the disease for which new therapeutic options are desperately needed. Previously, we showed that the high-affinity peroxisome proliferator–activated receptor γ (PPARγ) agonist, RS5444, inhibits cell proliferation of ATC cells via induction of the cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21). We show here that up-regulation of RhoB is a critical step in PPARγ-mediated activation of p21-induced cell stasis. Using multiple independently derived ATC cell lines, we found that treatment with RS5444 leads to the up-regulation of RhoB and subsequent activation of p21, and that silencing of RhoB by RNAi blocks the ability of RS5444 to induce p21 and to inhibit cell proliferation. Our results show that transcriptional regulation of RhoB by the nuclear transcription factor PPARγ is responsible for the induction of p21 mRNA and protein. We further implicate RhoB as a key signaling effector for the growth inhibition of ATC, as treatment with a histone deacetylase inhibitor shown to increase RhoB expression in lung cancer cells caused the up-regulation of RhoB in ATC cells accompanied by increased expression of p21 and inhibition of cell proliferation; this effect occurred even in ATC cells that were unresponsive to RS5444 due to a lack of expression of PPARγ. Our results implicate RhoB as a novel intermediate in critical signaling pathways and as an additional target for therapeutic intervention in ATC. [Cancer Res 2009;69(4):1536–44]

Abstract The PAX8/PPARγ (PPFP) fusion-oncogene is moderately specific for follicular thyroid carcinomas (FTC). It remains unknown whether this can be translated into improved diagnosis, classification, or outcome prediction. We studied a cohort of well-characterized follicular adenomas (FA), FTC, and Hürthle cell carcinomas (HCC) from patients with complete clinical follow-up, to determine whether PPARγ immunohistochemistry (as a surrogate of PAX8/PPARγ expression) helps to distinguish FA from FTC and to assess its diagnostic accuracy as an adjunct to frozen section. We also correlated PPARγ staining with clinical outcomes to assess its role as a prognostic marker. PPARγ staining was more common in FTC (31 of 54; 57%) than in HCC (one of 23; 4%) or FA (four of 31; 13%) (P < 0.000001). Adjunctive use of PPARγ immunohistochemistry improved diagnostic sensitivity of intraoperative frozen section from 84% to 96% (P < 0.05) but reduced specificity from 100% to 90% (P < 0.05). PPARγ staining was associated with favorable prognostic indicators (female gender, better tumor differentiation, and lesser risk of metastases). PPARγ staining may be helpful in the differential diagnosis of FA, FTC, and HCC, particularly when diagnostic sensitivity of histomorphology is reduced (e.g. during intraoperative frozen section). PPARγ staining also shows an association with favorable prognosis and may have a role in risk stratification.

Abstract Background Papillary thyroid cancer (PTC) has a generally favourable prognosis, but elderly patients with distant metastases or extracapsular invasion fair poorly. In small studies with short follow-up, young patients presenting with such extracapsular invasion and pulmonary metastases have faired well. This retrospective study was undertaken to clarify the long-term prognosis of such patients with advanced PTC. Methods Twenty-one children and young adults (median age 14 (range 6–20) years) presenting with PTC and pulmonary metastases were treated at a single institution between 1947 and 1998. Mean maximal tumour diameter was 4·65 cm. Initial surgical treatment consisted of total thyroidectomy (n = 16), subtotal thyroidectomy (n = 4) and isthmectomy (n = 1), coupled with a variety of lymph node dissections (n = 20). After operation, 19 patients were treated with ablative and incremental doses of iodine-131 until disease free. All patients were placed on suppressive thyroid hormone after operation. Mean length of follow-up was 21 years (range 3 months to 47 years). Follow-up was less than 3 years in four patients. All patients have undergone post-treatment radionucleotide and radiological evaluation. Results Nine of the 21 patients developed recurrent disease. The risk of recurrence at 5 years was 39 (95 per cent confidence interval 14–57) per cent. Eight had cervical lymph node recurrence and no patient developed recurrent pulmonary disease. All patients with identifiable recurrent disease underwent selective lymph node resection, which involved multiple resections in four. At follow-up, 18 patients remain completely free of disease, one patient has recurrent cervical node disease and two patients have died. The disease-free survival at 5 years was 95 (95 per cent confidence interval 86–100) per cent. Cause-specific death occurred in a single patient who died from extensive local disease at age 29 years after 12 years of multiple cervical lymph node recurrences. Conclusion A stepwise treatment approach including total thyroidectomy, high-dose iodine-131 treatment and early surgical reintervention for suspected local recurrent disease allows long-term survival and frequent ‘cure’ for young patients with PTC and concomitant pulmonary metastases.

It is uncertain whether more extensive primary surgery and increasing use of radioiodine remnant ablation (RRA) for papillary thyroid carcinoma (PTC) have resulted in improved rates of cause‐specific mortality (CSM) and tumor recurrence (TR). Details of the initial presentation, therapy, and outcome of 2444 PTC patients consecutively treated during 1940–1999 were recorded in a computerized database. Patients were followed for more than 43,000 patient‐years. The 25‐year rates for CSM and TR were 5% and 14%, respectively. Temporal trends were analyzed for six decades. During the six decades, the proportion with initial MACIS (distant Metastasis, patient Age, Completeness of resection, local Invasion, and tumor Size) scores <6 were 77%, 82%, 84%, 86%, 85%, and 82%, respectively (p = 0.06). Lobectomy accounted for 70% of initial procedures during 1940–1949 and 22% during 1950–1959; during 1960–1999 bilateral lobar resection (BLR) accounted for 91% of surgeries (p <0.001). RRA after BLR was performed during 1950–1969 in 3% but increased to 18%, 57%, and 46% in successive decades (p <0.001). The 40‐year rates for CSM and TR during 1940–1949 were significantly higher (p = 0.002) than during 1950–1999. During the last 50 years the 10‐year CSM and TR rates for the 2286 cases did not significantly change with successive decades. Moreover, the 10‐year rates for CSM and TR were not significantly improved during the last five decades of the study, either for the 1917 MACIS <6 patients or the 369 MACIS ? 6 patients. Increasing use of RRA has not apparently improved the already excellent outcome, achieved before 1970, in low risk (MACIS <6) PTC patients managed by near‐total thyroidectomy and conservative nodal excision.