Abstract
Cytochrome P450 1A1 (CYP1A1) is a phase I enzyme that regulates the metabolism of environmental carcinogens and alter the susceptibility to various cancers. Many studies have investigated the association between the CYP1A1 MspI and Ile462Val polymorphisms and digestive tract cancer (DTC) risk in different groups of populations, but their results were inconsistent. The PubMed and Embase Database were searched for case–control studies published up to 30th September, 2015. Data were extracted and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the relationship. Totally, 39 case–control studies (9094 cases and 12,487 controls) were included. The G allele in Ile/Val polymorphism was significantly associated with elevated DTC risk with per‐allele OR of 1.24 (95% CI = 1.09–1.41, P = 0.001). Similar results were also detected under the other genetic models. Evidence was only found to support an association between MspI polymorphism and DTC in the subgroups of caucasian and mixed individuals, but not in the whole population (the dominant model: OR = 1.19, 95% CI = 0.94–1.91, P = 0.146). In conclusion, our results suggest that the CYP1A1 polymorphisms are potential risk factors for DTC. And large sample size and well‐designed studies with detailed clinical information are needed to more precisely evaluate our founding.
Highlights
Digestive tract cancers (DTCs), well known as the most common malignant tumours globally, include oesophageal, gastric and colorectal cancers [1,2,3,4]
Many studies have been carried out to examine the association between the two polymorphisms of Cytochrome P4501A1 (CYP1A1) and risk of many cancers
95% confidence intervals (CIs) were calculated for CYP1A1 MspI/Ile462Val polymorphisms and DTC risk in each study
Summary
Digestive tract cancers (DTCs), well known as the most common malignant tumours globally, include oesophageal, gastric and colorectal cancers [1,2,3,4]. CYP1A1 gene consists of many single nucleotide polymorphisms (SNPs) These diverse variants could break the initial physiological equilibrium between activation and detoxification of metabolic carcinogens by adjusting the quantity and function of such enzyme. The two functional polymorphisms in CYP1A1gene, MspI (T >C, occurring in the noncoding 30 -flanking region, rs4646903) and Ile462Val Many studies have been carried out to examine the association between the two polymorphisms of CYP1A1 and risk of many cancers [9]. Funnel plot asymmetry was statistically assessed by Egger’s linear regression test (publication bias exists if P < 0.05). All statistical analyses were carried out by Stata software (version 12.0, StataCorp LP, College Station, TX, USA) [13,14,15]
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