High-resolution proteomics and metabolomics in thyroid cancer: Deciphering novel biomarkers

The incidence of thyroid cancer (TC) - the most common endocrine malignancy - has been increasing sharply since the mid-1990s. The rate of TC incidence in both men and women has been faster than any other cancer. Both improved diagnoses (i.e. increased medical surveillance and more sensitive diagnostic tests, such as ultrasound and confirmation via fine-needle aspiration biopsy (FNAB)), and environmental factors detrimental to thyroid health are thought to account for the increased incidence. There are several histological types of thyroid carcinoma including papillary, follicular, medullary, and anaplastic. Determining the type of TC is crucial for prognosis and treatment selection. Unfortunately, approximately 20-30% of patients undergoing FNAB have inconclusive or indeterminate results, leading to unnecessary surgical intervention in 80% of patients with benign nodules. To resolve this diagnostic dilemma, new biomarkers of TC are needed. Proteomic approaches offer an unbiased platform for the comprehensive analysis of the whole proteome. Although mRNA expression is widely considered to be indicative of protein expression, protein levels are the result of protein synthesis and degradation, yet RNA levels are only indicative of protein synthesis. Clinically, there is growing evidence for the role of proteomic and metabolomic technologies in TC biomarker discovery, providing novel information on the molecular events associated with TC, and potentially leading to the identification of novel drug targets. This review thoroughly discusses the importance of novel proteomic and metabolomic approaches to identify new biomarkers for TC.