Single Nucleotide Polymorphisms as Biomarkers for Drug Response and Toxicity in the Management of Colorectal Cancer Ashok Varma, Mathaiyan Jayanthi * and Deepak Gopal Shewade Jawaharlal Institute of Post Graduate Medical Education and Research, Pondicherry, India * Corresponding author: Mathaiyan Jayanthi, Jawaharlal Institute of Post Graduate Medical Education and Research, Pondicherry, India, Tel: 9442395291; E-mail: mailjayanthi@gmail.com Received date: April 16, 2018; Accepted date: May 07, 2018; Published date: May 17, 2018 Copyright: © 2018 Varma A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The current methods of cancer treatment don’t focus on the influence of interpatient genetic variations on the treatment outcomes. Genetic variations in the genes which are involved with drug metabolism and targets can affect treatment response and toxicity. In the recent time, many advances have been made to detect such candidate gene variations and use them as biomarkers in predicting the treatment outcomes in colorectal cancer (CRC). CRC remains one of the common causes of worldwide morbidity and mortality. In the last decade, many drugs have been approved including targeted therapies for the management of CRC which lead to improvement in the median survival and overall survival rate. However, there are significant variations in the response rate and toxicity among CRC patients with the current anti-cancer drugs. Interindividual response variations to chemotherapy can be influenced by several factors among them the genetic factor plays a key role. This emphasizes the need for the new genetic biomarkers which enable the selection of optimal drugs to benefit the patient care. This review focuses on single nucleotide polymorphisms which are known to affect the outcome of anticancer drugs used in the management of colorectal cancer. Keywords: Nucleotide; Biomarkers; Drug; Toxicity; Colorectal cancer Introduction Colorectal cancer (CRC) also known as bowel cancer, ofen begin as a small polyp on the inner wall of the colon or rectum. Polyps are benign and adenomatous in nature. Few of these polyps become cancerous over time [1]. Early fnding and removing of these polyps can prevent development of CRC. CRC is the third most commonly diagnosed cancer and the fourth leading cause of cancer-related deaths worldwide [2]. Incidence rates of CRC are similar in both the sexes, with a slight male predominance. As per globacon report 2012, CRC is the third most commonly seen cancer in men (10% of the total cancers) and second most in women (9.2% of total cancer). In India as per the Indian Council of Medical Research (ICMR) consensus document on management of colorectal cancer released in 2014, the annual incidence rates (AARs) for colon and rectal cancer in men and women are 4.4 and 3.9 per 100000 respectively [3]. Survival rate with CRC is highly dependent upon the disease stage at the time of diagnosis. In Asian countries, the overall cure rate has not been improved in spite of several improvements in CRC management. Te fve-year survival rate remains 60% in Asian countries. Te highest survival rates were found in China (60.8%), the lowest rate was reported in India (31.2%). In the United States, the 5- year survival rate of CRC is of 64%. Te failure to diagnose in early stages due to lack of regular screening is the main reason for low survival rates in Asian countries (Table 1) [4]. Drug Metabolism Drug targets 5-flurouracil & Capecitabine Dihydropyrimidine dehydrogenase Thymidylate synthase Oxaliplatin Glutathione S transferase DNA adducts Irinotecan UDP-glucuronosyl transferase Topoisomerase Cetuximab Reticuloendothelial system Epidermal growth factor receptor Panitumumab Reticuloendothelial system Epidermal growth factor receptor Bevacizumab Reticuloendothelial system Vascular endothelial growth factor A Table 1: Te table shows the current drugs used in CRC management, Respective metabolizing pathways and Drug targets. Te efcacy of drugs used in the management of CRC is ofen limited by signifcant interindividual variation. Such variations are ofen linked to single nucleotide polymorphisms either in the drug- metabolizing enzymes, DNA repair enzymes or in drug targets [5]. J o u r n a l o f P h a r m a c o g e n o m i c s & P h a r m a c o p r o t e o m i c s ISSN: 2153-0645 Journal of Pharmacogenomics & Pharmacoproteomics Varma et al., J Pharmacogenomics Pharmacoproteomics 2018, 9:2 DOI: 10.4172/2153-0645.1000178 Review Article Open Access J Pharmacogenomics Pharmacoproteomics, an open access journal ISSN: 2153-0645 Volume 9 • Issue 2 • 1000178