Biosensors and biomarkers: promising tools for cancer diagnosis

Cancer is one of the leading life-threatening diseases all over the world with over 200 types identified and higher than 1500 deaths occurring every day. Despite of recent technological advancements, late diagnosis and poor prognosis are leading reasons for poor survival rate of cancer patients. The conventional methods, including magnetic resonance imaging, biopsy and ultrasound are not efficient for early stage cancer detection, due to their dependence on the phenotypic properties of the tumor [1]. Cancer is a multistage disease, and a complex range of genetic and epigenetic alterations which disturb the cellular signaling are associated with its onset and progression and result in tumorigenic malignancy and transformation [2]. The biomarkers are molecules which undergo important alterations during cancer and carry high clinical significance. Biomarkers may be proteins, isoenzymes, nucleic acids, metabolites or hormones and are classified as prognostic, predictive and diagnostic [3]. Diagnostic biomarkers are used for the detection of the disease, whereas the information about course of recurrence of the disease is given by prognostic biomarkers. On the other hand, the response to treatment is estimated by predictive biomarkers [4,5]. The change in the level or presence or absence of specific biomarkers in a cell often is an indication of cancer development. Cancerspecific detection and identification of these biomarkers could help in early monitoring and diagnosis of disease progression [6]. The traditional enzyme-linked immunosorbent assay (ELISA) or Polymerase chain reaction (PCR) based methods for biomarkers detection; suffer technological limitations such as consumption of expensive reagents in every assay and slow detection [7]. Also, being manual techniques, these methods are not proficient in the continuous monitoring of the patient during treatment. Besides, within the cell multiple events are associated with all cancers involving more then one molecule. Thus simultaneous detection of multiple biomarkers for correct diagnosis and prognosis is required [8,9].