Novel Genomics and Proteomics Based Biomarkers to Predict Radiation Response and Normal Radiotoxicity in Cancer Patients for Personalized Medicine

Radiation therapy (RT) is one of the highly effective treatments option for clinically advanced tumor, and plays a prominent role in cancer therapy and prognosis. It is estimated that 62% of newly diagnosed cancer patients are treated with radiation therapy [1]. The efficacious radiation therapy depends upon the homogenous delivery of total dose which could eliminate tumor cells while protecting surrounding normal healthy tissues and avoid ancillary toxic effects [2,3]. Further, the tumor radioresistance and radiation-induced late toxicity can considerably limit treatment regularity, and cause hindrance in effective tumor control. In addition, late radiationinduced toxicity negatively impacts the quality of life of radiation treated patients and long term cancer survivors [4]. There are many latent side effects of radiation induced toxicity such as late toxicity response, epithelial tissue degeneration, infection, fibrosis and vascular lesions [5,6]. It is clinically well established that a significant number of patients develop radiation-induced toxic effects and currently, there is dearth of available technology which could precisely predict and monitor radiation induced side effects. Therefore, one of the major bottlenecks in radiation oncology is to deliver the effective targeted dose of radiation which could efficiently kill all the tumor cells, and at the same time ensure minimum normal tissue damage [4]. Nevertheless, in numerous clinical cases, the survival of cancer cells after radiotherapy can result in recurrence and disease progression. The global data have shown that up to 60% of prostate cancer patients receiving radiation therapy experience recurrence of the disease within 5 years of treatment [7]. Moreover, patients undergoing radiation therapy may exhibit radiation-induced resistance, fibrosis, and erectile dysfunction [8].