Published online Dec 28, 2017. doi: 10.3748/wjg.v23.i48.8533
Peer-review started: September 15, 2017
First decision: October 10, 2017
Revised: October 25, 2017
Accepted: November 8, 2017
Article in press: November 8, 2017
Published online: December 28, 2017
Processing time: 103 Days and 20.7 Hours
To evaluate the relation between 12 polymorphisms and the development of gastric cancer (GC) and colorectal cancer (CRC).
In this study, we included 125 individuals with GC diagnosis, 66 individuals with CRC diagnosis and 475 cancer-free individuals. All participants resided in the North region of Brazil and authorized the use of their samples. The 12 polymorphisms (in CASP8, CYP2E1, CYP19A1, IL1A, IL4, MDM2, NFKB1, PAR1, TP53, TYMS, UGT1A1 and XRCC1 genes) were genotyped in a single PCR for each individual, followed by fragment analysis. To avoid misinterpretation due to population substructure, we applied a previously developed set of 61 ancestry-informative markers that can also be genotyped by multiplex PCR. The statistical analyses were performed in Structure v.2.3.4, R environment and SPSS v.20.
After statistical analyses with the control of confounding factors, such as genetic ancestry, three markers (rs79071878 in IL4, rs3730485 in MDM2 and rs28362491 in NFKB1) were positively associated with the development of GC. One of these markers (rs28362491) and the marker in the UGT1A1 gene (rs8175347) were positively associated with the development of CRC. Therefore, we investigated whether the joint presence of the deleterious alleles of each marker could affect the development of cancer and we obtained positive results in all analyses. Carriers of the combination of alleles RP1 + DEL (rs79071878 and rs28361491, respectively) are at 10-times greater risk of developing GC than carriers of other combinations. Similarly, carriers of the combination of DEL + RARE (rs283628 and rs8175347) are at about 12-times greater risk of developing CRC than carriers of other combinations.
These findings are important for the comprehension of gastric and CRC development, particularly in highly admixed populations, such as the Brazilian population.
Core tip: Gastric cancer and colorectal cancer (CRC) are among the most incident and aggressive types of cancer in Brazil, especially in the Amazon region. Alterations in genes involved in pathways of immune responses, inflammatory processes or genomic and cellular stability may generate cellular imbalances and lead to tumorigenesis. Therefore, it is vital to understand the effect of different alleles in the development of gastric and CRC, which could contribute to the early detection of these types of cancer, increasing the survival chances of the patient.