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Can microRNA be used as a biomarker in adrenocortical cancer? “…microRNAs appear to have great potential as markers of malignancy or prognosis in adrenocortical tumors. Several promising data have been published to date supporting their potential applicability, but further larger scale studies are needed to confirm their usefulness and to find their place in clinical diagnostics.
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Keywords: adrenocortical cancer • biomarker • malignancy • microRNA • prognosis
The differential expression of microRNAs between normal and neoplastic tissues has been documented in several tumors [1] . Beside their obvious role in tumor pathogenesis, microRNAs can be exploited as diagnostic markers of malignancy that can be especially helpful for tumors whose histological diagnosis is difficult (e.g., in well differentiated thyroid tumors) [2] . Since microRNAs are very stable, microRNA profiling can be performed not only from frozen, but also from formalin-fixed paraffin-embedded tissues [3] . Apart from tissue microRNAs that can be retrieved from biopsy samples or removed tumors, novel data show that microRNAs can enter the circulation and show significant differences in expression in several forms of malignancy. Circulating microRNAs can thus be envisaged as potential minimally invasive markers of malignancy [4] . Adrenal tumors are common, and their prevalence increases with age. Most of these are hormonally inactive benign tumors of adrenocortical origin. Adrenocortical cancer (ACC) is rare with a yearly incidence of 0.5–2/million, however, it represents a major diagnostic and therapeutic challenge. The prognosis of ACC is poor in its advanced stages: the 5-year survival is 50 and 13% in stages 3 and 4, respectively [5] . The histological diagnosis of ACC is difficult, in part due to the severe limitations of the widely applied Weiss-score. Unfortunately, there is no reliable preoperative molecular marker of malignancy. Adrenal biopsy is very rarely performed for preoperative diagnosis due to the difficulties of histological analysis and to potential serious complication [5] . It
10.2217/IJE.14.39 © 2015 Future Medicine Ltd
is rather difficult to exclude malignancy in large (diameter >6 cm) and to confirm it in small adrenal tumors (diameter
