Positive Association between the Polymorphic Variant CCND1 A870G and Colorectal Cancer in Ecuadorian Mestizo Population

Abstract

Background: Colorectal cancer (CRC) is the fourth most common cause of cancer death worldwide and has an annual incidence of 917,000 cases. In Ecuador the CRC is the fifteenth most common form of cancer and the fourth leading cause of cancer deaths. Aim: Our goal was to establish frequencies related to the polymorphic variants: (CA)n in the EGFR gene and A870G in the CCND1 gene and their influence on the development of CRC in the Ecuadorian population. Methods: This is a retrospective case-control study consisting of colorectal cancer patients (n = 96 cancer tissues) compared to a control group (n = 62 adjacent healthy tissues). For the sequencing of the fragments, PCR and Sanger method was used. Results: The polymorphic variant A870G in CCND1 has a genotype frequency for the common homozygous G/G = 0.69, for the heterozygous A/G = 0.25 and for the less frequent homozygous A/A = 0.06 in the control group. We studied 7 alleles, repeats 14-19 have been reported in other studies, but the 13 repeats allele was first described here. The most common number of repetitions was 18 with a frequency of 0.326 in patients and 0.25 in controls (2 = 22.58, p <0.01). The odds ratio showed that the risk of developing colorectal cancer is 5 times greater if the individual is carrying the heterozygous G/A (p <0.01). Meanwhile, if the individual is carrying the allele 'A' the risk is 4 times more likely to develop this disease (p <0.01).