Reproductive factors and breast cancer risk: A meta-analysis of case-control studies in Indian women

Background/Objective:

India is the world's most biodiverse region and is undergoing a period of dramatic social and economic change. Due to population's explosion, climate change and lax implementation of environmental policies, the incidence of breast cancer is increasing. From population-based cancer registry data, breast cancer is the most common cancer in women in urban registries where it constitutes more than 30% of all cancers in females. We conducted a meta-analysis of all breast cancer case–control studies conducted in India during 1991–2018 to find pooled estimates of odds ratio (OR).

Materials and Methods:

Eligible studies were identified through a comprehensive literature search of PubMed, EMBASE, and HINARI databases from 1991 to January 2018. This analysis included 24 observational studies out of 34 that reported the case–control distribution of reproductive factors, body mass index (BMI) and type of residence. The analysis was performed using RevMan 5.3 (Review Manager, 2017) applying the random-effects model.

Results:

A total of 21,511 patients (9889 cases and 11,622 controls) were analyzed, resulting in statistically significant association between breast cancer and the following reproductive factors: never breastfeed (OR: 3.69; 95% confidence interval [CI]: 1.70, 8.01), menopausal age >50 years (OR: 2.88; 95% CI: 1.85, 3.85), menarche age <13 years (OR: 1.83; 95% CI: 1.34, 2.51), null parity (OR: 1.58; 95% CI: 1.21, 2.06), postmenopause (OR: 1.35; 95% CI: 1.13, 1.62), and age at the 1^st pregnancy >25 years (OR: 1.57; 95% CI: 1.37, 1.80). Family history (FH) of breast cancer (OR: 5.33; 95% CI: 2.89, 9.82), obesity (OR: 1.19; 95% CI: 1.00, 1.42), and urban residence (OR: 1.22; 95% CI: 1.03, 1.44) were also found to be significant risk factors.

Conclusion:

The results of this meta-analysis are indicative of significant associations between reproductive factors and breast cancer risk, profoundly so among women experiencing menopause after the age of 50, women who never breastfeed and FH of breast cancer.

Association of MCP-1 promoter polymorphism with susceptibility to nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is prevalent among populations from southern China and is influenced by both genetic and environmental risk factors. The monocyte chemoattractant protein-1 (MCP-1), a member of cysteine-cysteine chemokine family, plays critical roles in cancers. A polymorphism within the MCP-1 promoter, rs1024611, has been shown to be significantly associated with the risk of several cancers. Our purpose was to assess the role of rs1024611 in NPC susceptibility. By polymerase chain reaction-restriction fragment length polymorphism method, we genotyped rs1024611 in 593 patients with NPC (cases) and 480 cancer-free subjects (controls) among Guangxi population from southern China. We observed that the G allele of rs1024611 was significantly associated with the increased risk of NPC in an additive model and dominant model, respectively (P = 0.018 and 0.010, odds ratio = 1.25 and 1.41, respectively). No appreciable variation of the effects was found across the subgroups stratified by age, sex, nationality, smoking and drinking status, and smoking level. In addition, significantly higher messenger RNA (mRNA) expression level of MCP-1 was observed in NPC tissues than that in normal nasopharyngeal tissues, and the G allele of rs1024611 was significantly associated with elevated mRNA expression level of MCP-1 in Epstein-Barr virus-transformed lymphocytes. In conclusion, our findings suggested that rs1024611 at the MCP-1 promoter may be a risk factor for NPC. Further studies with larger sample size are necessary to confirm these findings.

The rs1024611 in the CCL2 gene and risk of gynecological cancer in Asians: a meta-analysis

BACKGROUND

The -2518A/G (rs1024611) polymorphism of the CCL2 (C-C motif chemokine ligand 2), also known as MCP-1 (monocyte chemotactic protein-1) gene, has been reported to be associated with increased gynecological cancer risk, but the results are conflicting.

METHODS

In this analysis, 1089 cases and 1553 controls from six publications were used to investigate the association between CCL2-2518A/G (rs1024611) polymorphism and the risk of gynecological cancer with a meta-analytic approach. Studies published on EBSCO, EMBASE, Web of Science, PubMed, SpringerLink, ScienceDirect, Weipu, and CNKI databases were identified (last update was on November 3, 2015). Six articles focused on the association between CCL2-2518A/G (rs1024611) polymorphism, and gynecological cancer risk was selected and data were extracted. The cancer type included endometrial cancer (n = 1), breast cancer (n = 2), ovarian cancer (n = 2), and cervical cancer (n = 1). All statistical analyses were performed using the STATA version 12.0 software.

RESULTS

The meta-analysis showed that CCL2-2518A/G (rs1024611) polymorphism is associated with risk of gynecological cancer (GG vs AG + AA, OR = 1.55, 95%CI = 1.07-2.24, P < 0.05; AA vs GG, OR = 0.59 95%CI = 0.38-0.92, P < 0.05). Notably, the subgroup analysis demonstrated that the genotype AA is associated with a reduced gynecological cancer risk in Asians, but an increased risk when compared to AG in Europeans.

CONCLUSIONS

Our data demonstrated the CCL2-2518A/G (rs1024611) polymorphism is significantly associated with risk of gynecological cancer, and the association differs by ethnicity.

The association of genetic variants in chemokine genes with the risk of psoriasis vulgaris in Chinese population: A case-control study

This study aimed to investigate the influence of polymorphisms in chemokine genes, including MCP1, CCR2, and CCR5 with psoriasis vulgaris (PV) risk in a Chinese population.The genotyping of studied polymorphisms through polymerase chain reaction (PCR) and sequencing was conducted in 142 PV patients and 147 healthy controls. The genotype distribution of the polymorphisms in the control group was checked to determine whether it conformed to Hardy-Weinberg equilibrium (HWE). The genotype and allele frequencies were compared between PV patients and the healthy controls using Chi-square test. Odds ratio (OR) with 95% confidence interval (95% CI) was calculated to assess the relative risk of PV related to genetic variants.CCR2 rs1799864 polymorphism was associated with significantly elevated risk of PV (AA+AG vs GG: OR = 1.62, 95% CI = 1.02-2.59; A vs G: OR = 1.48, 95% CI = 1.02-2.16). In the meanwhile, CCR5 rs1800024 polymorphism also exhibited significant differences in genotype and allele distribution (P < .05), demonstrating its promoting effect on the risk of PV under heterozygous model (OR = 1.73, 95% CI = 1.06-2.82), dominance model (OR = 1.83, 95% CI = 1.14-2.94), and allele model (OR = 1.68, 95% CI = 1.13-2.48).CCR2 rs1799864 and CCR5 rs1800024 polymorphisms may function as independent risk factors for PV in Chinese population.