So here comes the question: what will future clinical trials for knee OA and OA in general evaluate: novel pharmaceuticals, novel nutraceuticals, improved stem cell therapies? FAK agonist Footnotes P- Reviewer: Chen YK, Fenichel I, Yao YC, Zhai G S- Editor: Tian YL L- Editor: A

E- Editor: Lu YJ
Core tip: The concept of cancer stem cells in thyroid gland tumors has recently evolved. Since this sub-population of cells appear to have a potential for self-renewal and cell differentiation, their role envisions newer ideas in the field of anti-cancer therapy and regenerative medicine. The controversies have been raised for their origin in different cell lines and effectiveness in thyroid pathologies including chemo- and radio-resistant thyroid cancer. Newer concepts like epithelial-mesenchymal

transition have been investigated to define its role in metastatic activity. Literature discusses various methods to target these cells by interfering signaling pathways, destruction of niche and other factors which facilitate and sustain tumor growth. INTRODUCTION The incidence of thyroid cancer is rapidly rising in the US accounting for 62980 cases with 1890 deaths every year[1]. It is the seventh most common cancer diagnosed in women and peaks earlier than in men. Despite its high prevalence, death rate from thyroid cancer is fairly stable from past many years. In general, thyroid cancer offers a good prognosis with an overall survival rate of approximately 90%[2]. Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) termed as differentiated thyroid cancer (DTC) contribute to majority of thyroid cancers sharing a superior prognosis. Medullary thyroid carcinoma (MTC), mostly acquired as a part of familial syndromes, display only modest cure rates. While surgical resection followed by radioiodine therapy remains the treatment of choice for localized thyroid cancer, it fails to eradicate tumors with aggressive behavior. In marked contrast to DTC, anaplastic carcinoma

(ATC), an undifferentiated sub-type of thyroid cancer, has a higher propensity Anacetrapib to locally invade nearby structures and metastasize rapidly. It approaches to almost 50% of all thyroid cancer-related deaths, the median survival being only six months[3]. The grim prognosis of ATC is due to the fact that it is diagnosed at an advanced stage which offers palliative treatment as the only option for patients suffering from the disease. Because of the chemo- and radio-resistant nature observed in aggressive thyroid cancers, many researchers have been continuously attempting to create new treatment strategies that are aimed at eradication of cancer cells. These trials led to a phenomenal breakthrough that the acquired resistance of thyroid cancer cells which initially were responding to conventional therapies may harbor heterogeneous cell types.