Previous studies have examined the association between ABO blood group and ovarian cancer risk, with inconclusive results.

Many studies have examined the association between the CYP1A1 Ile462Val gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent. To assess this relationship more precisely, a meta-analysis was performed. Ultimately, 43 case-control studies, comprising 19,228 subjects were included. A significantly elevated lung cancer risk was associated with 2 Ile462Val genotype variants (for Val/Val vs Ile/Ile: OR = 1.22, 95% CI = 1.08-1.40; for (Ile/Val +Val/Val) vs Ile/Ile: OR = 1.15, 95% CI = 1.07-1.23) in overall population. In the stratified analysis, a significant association was found in Asians, Caucasians and lung SCC, not lung AC and lung SCLC. Additionally, a significant association was found in smoker population and not found in non-smoker populations. This meta-analysis suggests that the Ile462Val polymorphisms of CYP1A1 correlate with increased lung cancer susceptibility in Asian and Caucasian populations and there is an interaction with smoking status, but these associations vary in different histological types of lung caner.

MicroRNAs (miRNAs) are small non-coding RNA molecules, which act as post-transcriptional regulators of gene expression and have been implicated in initiation, progression and treatment outcome of diverse cancers. Single nucleotide polymorphisms (SNPs), as the most common type of genetic variation, also exist in miRNA genes and can lead to alteration in miRNA expression resulting in diverse functional consequences. Emerging studies have evaluated the association of miRNA SNPs with cancer risk, but the results remain inconclusive. To assess the relationship between miRNA SNPs and cancer risk, we performed a meta-analysis of 18 studies involving 20660 subjects for miR-146a rs2910164 polymorphism and 21 studies involving 26,018 subjects for miR-196a2 rs11614913 polymorphism. As for rs2910164, no significant association of cancer risk was found in the overall analysis. In subgroup analysis by cancer type, ethnicity, source of controls and sample size, significant association of cancer risk was mainly found in papillary thyroid carcinoma, primary liver cancer, cervical cancer, Caucasian population and small sample size studies. For rs11614913, significant results were found in all the tested genetic models and T allele or its carriers were associated with decreased cancer risk in overall analysis (T vs. C: OR = 0.888, 95% CI 0.84-0.938; TT+TC vs. CC: OR = 0.897, 95% CI 0.828-0.971). In stratified analysis by cancer type and ethnicity, significant association of cancer risk was observed in breast cancer, lung cancer, colorectal cancer and Asian population, but not in Caucasian population. During further stratified analysis by source of controls and sample size, results similar to those of overall analysis were found in all of the subgroups. Taken together, our results indicated that miR-196a2 rs11614913 T variant probably contribute to decreased susceptibility to cancer. However, limited evidence was found for association of miR-146a rs2910164 with cancer risk, and further well-designed studies with large sample size will be necessary to validate the effect of miR-146a rs2910164 on cancer susceptibility.

5,10-methylenetetrahydrofolate reductase (MTHFR) variants, C677T and A1298C, have been reported to be associated with decreased risk of acute lymphoblastic leukemia (ALL). However, results derived from individually underpowered studies are conflicting. We carried out an updated meta-analysis on the association between MTHFR polymorphisms and ALL risk.

Emerging evidence from preclinical and clinical studies has shown that interleukin-12 (IL-12) has some effectiveness against endogenously arising carcinogenesis. Several potentially functional polymorphisms of IL-12 gene have been implicated in cancer risk, but individually published studies showed inconclusive results. The aim of this study was to investigate the association between IL-12 polymorphisms and cancer risk.

Multiple studies have reported associations between the PSCA rs2294008 C>T polymorphism and GC, but susceptibility has proven inconsistent. Therefore, we estimates the relationship between the rs2294008 C>T polymorphism and GC by meta-analysis.

Previous studies assessing associations between matrix metalloproteinase 2 (MMP-2) polymorphisms and lung cancer risk reported conflicting results. A meta-analysis was therefore performed to derive a more precise estimation.

Many studies have investigated the association between the MDM2 promoter SNP309 T/G polymorphism and liver cancer risk, but inconsistencies make drawwing definitive conclusions difficult.

Many studies have investigated the association between glutathione S-transferase T 1 (GSTT1) null genotype and risk of prostate cancer, but the impact of GSTT1 null genotype in Asians is still unclear owing to inconsistencies across results. Thie present meta-analysis aimed to quantify the strength of the association between GSTT1 null genotype and risk of prostate cancer.

Studies investigating the association of 2R/3R polymorphism in the thymidylate synthase 5'-untranslated enhanced region (TSER) and colorectal cancer (CRC) risk have reported conflicting results. Thus, a meta-analysis was performed to summarize the data on the potential association.

Methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme involved in folate metabolism; a single nucleotide polymorphism (SNP) C677T has been reported to be linked with altered incidences of several diseases. We here conducted a meta-analysis of 15 published epidemiological studies with a total of 7306 cases and 8062 controls to evaluate its association with prostate cancer risk with overall and subgroup analyses. No statistical relationship was found overall with any genetic model (TT vs. CC: OR = 0.80, 95%CI = [0.62, 1.04], P = 0.094; CT vs. CC: OR = 0.97, 95%CI = [0.84; 1.12], P = 0.667; Dominant: OR = 0.94, 95%CI = [0.82; 1.07], P = 0.343; Recessive: OR = 0.81, 95%CI = [0.64; 1.04], P = 0.104), but after the exclusion of several studies, we could observe the homozygote TT to confer less susceptibility to prostate cancer in carriers; moreover, different effects of the polymorphism on prostate cancer risk was detected from subgroup analysis stratified by participants' residential region: significant reduced prostate cancer risk was found to be associated with the polymorphism from Asian studies (TT vs. CC: OR = 0.47, 95%CI = [0.33; 0.67], P< 0.001; CT vs. CC: OR = 0.73, 95%CI = [0.60; 0.90], P = 0.002; Dominant: OR = 0.67, 95%CI = [0.56; 0.82], P< 0.001; Recessive: OR = 0.55, 95%CI = [0.40; 0.76], P< 0.001) while studies from Europe indicated a slight increased risk under dominant model with marginal significance (OR = 1.14, 95%CI = [0.99; 1.30], P = 0.064). Moreover, the protective effect of the polymorphism against prostate cancer was also shown by studies performed in yellow Asians (TT vs. CC: OR = 0.48, 95%CI = [0.31; 0.75], P = 0.001; CT vs. CC: OR = 0.68, 95%CI = [0.51; 0.90], P = 0.006; Dominant: OR = 0.63, 95%CI = [0.48; 0.82], P < 0.001; Recessive: OR = 0.57, 95%CI = [0.39; 0.84], P = 0.004). We propose that these phenomena should be viewed with the consideration of folate metabolism profile and different gene background as well as living habits of different populations, and more relevant studies should be conducted to confirm our hypothesis and provide a comprehensive and clear picture concerning this topic.

ABCG2, also known as BCRP, is a half ATP-binding cassette (ABC) transporter that localizes to plasma membranes. Recently, a number of studies have investigated the relationship between the C421A polymorphism in ABCG2 and cancer risk in multiple populations and various types of cancers; however, this relationship remains unclear. Therefore, we performed a meta-analysis to further explore this association.

Clinicians have long sought to characterize biological markers of neoplasia as objective indicators of tumor presence, pathogenicity, and prognosis. Armed with data that correlate biomarker activity with disease presence and progression, clinicians can develop treatment strategies that address risks of disease recurrence or persistence and progression. The B-type Raf kinase (BRAF V600E) mutation in exon 15 of the BRAF gene has been noted to be a putative prognostic marker of the most prevalent form of thyroid cancer, papillary thyroid cancer (PTC)--a tumor type with high proclivity for recurrence or persistence. There has been a remarkable interest in determining the association of BRAF mutation with PTC recurrence or persistence. Using many new studies that have been published recently, we performed a meta-analysis to investigate correlations of BRAF mutation status with PTC prognosis, focusing on the recurrence or persistence of the disease after initial treatment. The study was based on published studies included in the PubMed and Embase databases addressing the BRAF mutation and the frequency of recurrence of PTC. We selected studies with data that enabled measurement of the risk ratio for recurrent disease. We also analyzed the factors that are classically known to be associated with recurrence. These factors included lymph node metastasis, extrathyroidal extension, distant metastasis, and American Joint Committee on Cancer (AJCC) stages III/IV. We used 14 articles that included an analysis of these factors as well as PTC recurrence data, with a total of 2470 patients from 9 different countries. The overall prevalence of the BRAF mutation was 45%. The risk ratios in BRAF mutation-positive patients were 1.93 (95% confidence interval [CI], 1.61-2.32; Z = 7.01; p < 0.00001) for PTC recurrence, 1.32 (95% CI, 1.20-1.45; Z = 5.73; p < 0.00001) for lymph node metastasis, 1.71 (95% CI, 1.50-1.94; Z = 8.09; p < 0.00001) for extrathyroidal extension, 0.95 (95% CI, 0.63-1.44; Z = 0.23; p = 0.82) for distant metastasis, and 1.70 (95% CI, 1.45-1.99; Z = 6.46; p < 0.00001) for advanced stage AJCC III/IV. Thus, in this meta-analysis, the BRAF mutation in PTC was significantly associated with PTC recurrence, lymph node metastasis, extrathyroidal extension, and advanced stage AJCC III/IV. Patients with PTC harboring mutated BRAF are likely to demonstrate factors that are associated with an increased risk for recurrence of the disease, offering new prospects for optimizing and tailoring initial treatment strategies to prevent recurrence.

Platinum-based regimens are used as standard first-line chemotherapy in non-small cell lung cancer (NSCLC) patients. To study if pharmacogenetic approach may allow a tailored selection of platinum chemotherapy for advanced NSCLC, we performed a meta-analysis to compare chemosensitivity to platinum with different ERCC1 C118T/ MDR1 C3435T single-nucleotide polymorphism (SNP).

Microsomal epoxide hydrolase (EPHX1) plays an important role in both the activation and detoxification of PAHs, which are carcinogens found in cooked meat and tobacco smoking. Polymorphisms at exons 3 and 4 of the EPHX1 gene have been reported to be associated with variations in EPHX1 activity. The aim of this study is to quantitatively summarize the relationship between EPHX1 polymorphisms and colorectal cancer (CRC) risk.

MicroRNAs (miRNAs) are a family of endogenous, small and noncoding RNAs that negatively regulate gene expression by suppressing translation or degrading mRNAs. Recently, many studies investigated the association between hsa-miR-499 rs3746444 polymorphism and cancer risk, which showed inconclusive results.

To perform a systematic meta-analysis to investigate the association between X-ray repair cross-complementing group 1 (XRCC1) polymorphisms and hepatocellular carcinoma (HCC) risk.

The association between the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene C609T polymorphism and gastric cancer has been widely evaluated, yet with conflicting results. Data were available from seven study populations involving 2600 subjects. Overall, comparison of alleles 609T and 609C indicated a significantly increased risk (46%) for gastric cancer (95% confidence interval (95%CI) for odds ratio (OR) = 1.20-1.79) in individuals with the T allele. The tendency was increased in the homozygous comparison (609TT versus 609CC), with an OR = 2.04 (95%CI = 1.37-3.05). Stratified analysis by study design demonstrated stronger associations in population-based studies than in hospital-based studies, based on OR. Ethnicity-based analysis demonstrated a significant association in Asians but not in Caucasians. Additionally, in the subgroup analyses by the type of gastric cancer, a significantly increased risk was found with all genetic models in the gastric adenocarcinoma subgroup compared to the others. We conclude that the NQO1 gene C609T polymorphism increases the risk for gastric cancer, especially in Asian populations.

Published evidence concerning association of CYP1A1*2A (MspI) variation with oral carcinoma risk has generated controversial results. Our previous meta-analysis in 2008 failed to reveal a marked association between CYP1A1*2A polymorphism and oral cancer susceptibility. Therefore, updated meta-analyses were conducted. Results suggested significant associations between CYP1A1*2A polymorphisms and oral carcinoma risk for the overall data, inconsistent with our previous meta-analysis. In subgroup analyses by ethnicity, variant C allele might elevate oral cancer susceptibility among Asians but not Caucasians. In conclusion, results suggest that CYP1A1*2A polymorphism might be a low-penetrant risk factor for oral carcinoma, particularly among Asians.