The Val158Met polymorphism in the COMT gene is associated with increased cancer risks in Chinese population

The Val158Met polymorphism in the COMT gene may affect the DNA repair pathways and be associated with the risk of cancer in Chinese population. However, the results of previous studies are inconsistent. The objective of this study was to investigate the association between the Val158Met polymorphism in the COMT gene and the risk of cancer for Chinese population by meta-analysis. We searched PubMed, Embase, CNKI, Weipu, and Wanfang databases, and the last search was updated on Sep. 26, 2013. Statistical analysis was performed using the Revman4.2 and Stata10.0 software. A total of 18 case–control studies concerning 5034 case and 6234 controls were included. In the total analysis, the results suggested a significant association between the Val158Met polymorphism in the COMT gene and the cancer risk in Chinese population: OR?=?1.34, 95 %CI?=?1.04–1.73, and P?=?0.03 for AA vs. AG?+?GG; OR?=?1.39, 95 %CI?=?1.06–1.82, and P?=?0.02; OR?=?1.13, 95 %CI?=?1.01–1.27, and P?=?0.04. In the subgroup analysis by cancer types, significant association was found in the breast cancer and esophageal squamous cell carcinoma. The current meta-analysis confirmed that the Val158Met polymorphism in the COMT gene may be a risk factor for cancer in Chinese population. In the future, more case–control studies are needed to validate our results.     

Lack of association between catechol-O-methyltransferase Val108/158Met polymorphism and breast cancer risk: a meta-analysis of 25,627 cases and 34,222 controls

Epidemiological studies have evaluated the association between catechol-O-methyltransferase (COMT) Val108/158Met polymorphism and breast cancer risk. However, the results remain conflicting rather than conclusive. In order to derive a more precise estimation of the relationship, we performed this meta-analysis. Systematic searches of the PubMed and Medline databases were performed. A total of 41 studies including 25,627 cases and 34,222 controls were identified. Genotype distributions of COMT in the controls of all studies were in agreement with the Hardy–Weinberg equilibrium (HWE) except for three studies. When all 41 studies were pooled into the meta-analysis, there was no evidence for significant association between COMT Val108/158Met polymorphism and breast cancer risk (for Val/Met vs. Val/Val: OR = 0.99, 95% CI = 0.93–1.04; for Met/Met vs. Val/Val: OR = 0.96, 95% CI = 0.88–1.04; for dominant model: OR = 0.97, 95% CI = 0.92–1.03; for recessive model: OR = 0.97, 95% CI = 0.90–1.04). In the subgroup analyses by ethnicity, menopausal status, no significant associations were found in all genetic models. When sensitivity analyses were performed by excluding HWE-violating studies, all the results were not materially altered. In summary, the meta-analysis strongly suggests that COMT Val108/158Met polymorphism is not associated with increased breast cancer risk.     

Combined effect of CYP1B1, COMT, GSTP1, and MnSOD genotypes and risk of postmenopausal breast cancer

Objective

Estrogen plays a key role in breast cancer development and functionally relevant genetic variants within the estrogen metabolic pathway are prime candidates for a possible association with breast cancer risk. We investigated the independent and the combined effects of commonly occurring polymorphisms in four genes encoding key proteins of estrogen metabolic pathway on their potential contribution to breast cancer risk.

Methods

We studied 530 breast cancer cases and 270 controls of the same age and ethnicity participating in a case-control study of postmenopausal women. Genotyping was conducted for CYP1B1 (rs1056836), COMT (rs4680), GSTP1 (rs1695), and MnSOD (rs4880) polymorphisms by polymerase chain reaction based restriction fragment length polymorphism and TaqMan allelic discrimination method. Adjusted ORs and 95% CIs were calculated using logistic regression.

Results

None of the 4 genetic variants examined contributed to breast cancer risk individually. When the combined effects of the risk genotypes were investigated, significant associations were observed among women with two high-risk genotypes in CYP1B1 and COMT (OR, 2.0; 95% CI, 1.1 to 3.5) and two high-risk genotypes in COMT and MnSOD (OR, 2.0; 95% CI, 1.0 to 3.8), compared to those with low-risk genotypes.

Conclusion

Our results suggest that individual susceptibility to breast cancer incidence may be increased by combined effects of the high-risk genotypes in CYP1B1, COMT, and MnSOD estrogen metabolic genes.     

The association between ATM D1853N polymorphism and breast cancer susceptibility: a meta-analysis

Background

Emerging evidence suggests that ataxia telangiectasia-mutated (ATM) is involved in numerous damage repair signaling pathways and cell-cycle checkpoints. Heterozygous carriers of ATM-mutations have an increased risk for the development of breast cancer. The purpose of this study is to evaluate the association between ATM exon39 5557G > A (D1853N, rs1801516) polymorphism and breast cancer susceptibility with the use of a meta-analysis.

Methods

By searching PubMed and Embase databases, a total of 9 epidemiological studies with 4,191 cases and 3,780 controls were identified. Crude odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) for ATM D1853N polymorphism and breast cancer risk were calculated using fixed- or random-effects model based on the degree of heterogeneity among studies.

Results

No significant association between the ATM D1853N polymorphism and breast cancer risk was observed in overall analysis (GA versus GG: OR = 1.18; 95% CI, 0.90-1.53; AA versus GG: OR = 0.77; 95% CI, 0.58-1.03; dominant model: OR = 1.16; 95% CI, 0.89-1.51; and recessive model: OR = 0.78; 95% CI, 0.59-1.04, respectively).

Conclusion

Our results indicate that ATM D1853N polymorphism is not a risk factor for developing breast cancer.     

Hypoxia-inducible factor-1α gene polymorphisms and cancer risk: a meta-analysis

Background

The results from the published studies on the association between hypoxia-inducible factor -1α (HIF-1α) polymorphisms and cancer risk are conflicting. In this meta-analysis, we aimed to investigate the association between HIF-1α 1772 C/T and 1790 G/A polymorphisms and cancer.

Methods

The meta-analysis for 1772 C/T polymorphism included 4131 cancer cases and 5387 controls, and for 1790 G/A polymorphism included 2058 cancer cases and 3026 controls. Allelic and genotypic comparisons between cases and controls were evaluated. Subgroup analyses by cancer types, ethnicity, and gender were also performed. We included prostate cancer in male subgroup, and female specific cancers in female subgroup.

Results

For the 1772 C/T polymorphism, the analysis showed that the T allele and genotype TT were significantly associated with higher cancer risk: odds ratio (OR) = 1.29 [95% confidence interval (CI, 1.01, 1.65)], P = 0.04, P_{heterogeneity} < 0.00001, and OR = 2.18 [95% CI (1.32, 3.62)], P = 0.003, P_{heterogeneity} = 0.02, respectively. The effect of the genotype TT on cancer especially exists in Caucasians and female subjects: OR = 2.40 [95% CI (1.26, 4.59)], P = 0.008, P_{heterogeneity} = 0.02, and OR = 3.60 [95% CI (1.17, 11.11)], P = 0.03, P_{heterogeneity} = 0.02, respectively. For the 1790 G/A polymorphism, the pooled ORs for allelic frequency comparison and dominant model comparison suggested a significant association of 1790 G/A polymorphism with a decreased breast cancer risk: OR = 0.28 [95% CI (0.08, 0.90)], P = 0.03, P_{heterogeneity} = 0.45, and OR = 0.29 [95% CI (0.09, 0.97)], P = 0.04, P_{heterogeneity} = 0.41, respectively. The frequency of the HIF-1α 1790 A allele was very low and only two studies were included in the breast cancer subgroup.

Conclusions

Our meta-analysis suggests that the HIF-1α 1772 C/T polymorphism is significantly associated with higher cancer risk, and 1790 G/A polymorphism is significantly associated with decreased breast cancer risk. The effect of the 1772 C/T polymorphism on cancer especially exists in Caucasians and female subjects. Only female specific cancers were included in female subgroup, which indicates that the 1772 C/T polymorphism is significantly associated with an increased risk for female specific cancers. The association between the 1790 G/A polymorphism and lower breast cancer risk could be due to chance.     

Brain-derived neurotrophic factor genetic polymorphism (rs6265) is protective against chemotherapy-associated cognitive impairment in patients with early-stage breast cancer

Background

Brain-derived neurotrophic factor (BDNF), a neurotrophin that regulates neuronal function and development, is implicated in several neurodegenerative conditions. Preliminary data suggest that a reduction of BDNF concentrations may lead to postchemotherapy cognitive impairment. We hypothesized that a single nucleotide polymorphism (rs6265) of the BDNF gene may predispose patients to cognitive impairment. This study aimed to evaluate the effect of BDNF gene polymorphism on chemotherapy-associated cognitive impairment.

Methods

Overall, 145 patients receiving chemotherapy for early-stage breast cancer (mean age: 50.8 ± 8.8 y; 82.1% Chinese) were recruited. Patients'' cognitive functions were assessed longitudinally using the validated Functional Assessment of Cancer Therapy–Cognitive Function (v.3) and an objective computerized tool, Headminder. Genotyping was performed using Sanger sequencing. Logistic regression was used to evaluate the association between BDNF Val66Met polymorphism and cognition after adjusting for ethnicity and clinically important covariates.

Results

Of the 145 patients, 54 (37%) reported cognitive impairment postchemotherapy. The Met/Met genotype was associated with statistically significant lower odds of developing cognitive impairment (odds ratio [OR] = 0.26; 95% CI: 0.08–0.92; P = .036). The Met carriers were less likely to experience impairment in the domains of verbal fluency (OR = 0.34; 95% CI: 0.12–0.90; P = .031) and multitasking ability (OR = 0.37; 95% CI: 0.15–0.91; P = .030) compared with the Val/Val homozygote. No associations were observed between Headminder and the BDNF Val66Met polymorphism.

Conclusions

This is the first study to provide evidence that carriers of the BDNF Met allele are protected against chemotherapy-associated cognitive impairment. Further studies are required to validate the findings.     

XPC polymorphism increases risk of digestive system cancers: Current evidence from a meta-analysis

Objective: Xeroderma pigmentosum complementation group C (XPC) participates in the initial recognition of DNA damage during nucleotide excision repair process in global genomic repair. Our meta-analysis was performed to evaluate the association between three polymorphisms (Lys939Gln, PAT+/- and Ala499Val) of XPC gene and risk of digestive system cancers. Methods: All the relevant case-control studies published to April 2011 were identified through searching PubMed. Digestive system cancer risk with the three polymorphisms was estimated for each study by odds ratio (OR) with its 95% confidence interval (95% CI). Results: We found an increased overall risk for digestive system cancers in all three models of Lys939Gln A>C (AC/CC vs. AA: OR, 1.20; 95% CI, 1.11-1.30; CC vs. AC/AA: OR, 1.24; 95% CI, 1.11-1.39; CC vs. AA: OR, 1.36; 95% CI, 1.21-1.53). When strati?ed by ethnicity, results remained significant in Asian population (AC/CC vs. AA: OR, 1.18; 95% CI, 1.02-1.37; CC vs. AC/AA: OR, 1.32; 95% CI, 1.1-1.51; CC vs. AA: OR, 1.35; 95% CI, 1.08-1.70), but not for Caucasians. However for Ala499Val C>T, a significant protective effect of T allele was only observed in the dominant model. Otherwise, no significant results were observed for PAT+/-. Conclusion: XPC Lys939Gln A>C polymorphism may play an important role in digestive system cancer susceptibility.     

Case-Control Study on the Fibroblast Growth Factor Receptor 2 Gene Polymorphisms Associated with Breast Cancer in Chinese Han Women

Purpose

Genetic variation in fibroblast growth factor receptor 2 (FGFR2) is a newly described risk factor for breast cancer. This study aimed to evaluate the association of four single nucleotide polymorphisms (SNPs) in FGFR2 with breast cancer in Han Chinese women.

Methods

Two hundred three women with breast cancer and 200 breast cancer-free age-matched controls were selected. Four SNPs (rs2981579, rs1219648, rs2420946, and rs2981582) and their haplotypes were analyzed to test for their association with breast cancer susceptibility. The presence of the four FGFR2 SNPs was determined by polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

A statistically significant difference was observed in the frequency of rs2981582 in the FGFR2 gene (p<0.05) between case and control groups. In subjects stratified by menopausal status, rs2981582 TT, rs2420946 AA, and rs1219648 CC were significantly associated with the risk of breast cancer in postmenopausal subjects, but no significant associations between these four SNPs and the risk of breast cancer were identified in premenopausal subjects. Further, there was no significant association between hormone receptor status (estrogen receptor and progesterone receptor) and breast cancer risk. Six common (> 3%) haplotypes were identified. Three of these haplotypes, CGTC (odds ratio [OR], 0.613; 95% confidence interval [CI], 0.457-0.82; p=0.001), TGTC (OR, 6.561; 95% CI, 2.064-20.854; p<0.001), and CATC (OR, 12.645; 95% CI, 1.742-91.799; p=0.001) were significantly associated with breast cancer risk.

Conclusion

Our findings indicated that the SNP rs2981582 and haplotypes CGTC, TGTC, and CATC in FGFR2 may be associated with an increased risk of breast cancer in Han Chinese women.     

中国人群COMT Val158Met基因多态性与乳腺癌易感性Meta分析

目的：系统评价中国人群儿荼酚氧位甲基转移酶（catechol-O-methyltransferase,COMT）Vall58Met基因多态性与乳腺癌易感性的关系。方法：在PubMed、MEDLINE、webofScience、Embase、中国期刊全文数据库（CJFD）及万方数据库中检索1999-10-01-2012-01-01发表的所有有关中国人群COMTVall58Met基因多态性与乳腺癌易感性关系的相关文献,并按STREGA原则对文献进行筛选、评价。纳入文献均为病例对照研究,对照群体基因型分布均符合H-W遗传平衡定律。应用Stata 12．0软件进行Meta分析,计算合并0R值及95％CI,并进行敏感性分析和发表偏倚的估计。结果：按照入选标准,有11项病例对照研究纳入,包括乳腺癌患者3184例,健康对照4065例。Meta分析结果显示,与基因型Val／Val（GG）、Val／Met（GA）比较,基因型Met／Met（AA）均增加中国人群罹患乳腺癌的风险[OR=1．55,95％CI：1.03～2．33,P=0．035;OR-1．63,95％CI：1．10～2．42,P=0．015];在隐性效应模型（Met／Met／vs Val／Val＋Val／Met）中,基因型Met／Met（AA）增加中国人群罹患乳腺癌的风险,0R-1．59,95％CI：1．07～2．36,P=0．021。与等位基因Val（G）比较,等位基因Met（A）不增加中国人群罹患乳腺癌的风险,OR=1．12,95％CI：0．96～1．32,P=0．157。结论：COMTVall58Met基因多态性与中国人群乳腺癌易感性相关,基因型Met／Met（AA）增加中国人群罹患乳腺癌的风险。     

Catechol-O-methyltransferase Val158Met polymorphism and breast cancer risk in Asian population

The association between the polymorphism of catechol-O-methyltransferase (COMT) Val158Met and breast cancer risk is still inconclusive. We performed a meta-analysis to derive a more precise estimation of the relationship. A total of 18 studies including 5,175 cases and 6,463 controls were involved in this meta-analysis. When all studies were pooled into the meta-analysis, no significantly elevated breast cancer risk was associated with all genetic models (for additive model: OR?=?1.273, 95 % CI?=?0.947–1.711, P _{heterogeneity}?=?0.000; P?=?0.110; for dominant model: OR?=?1.080, 95 % CI?=?0.945–1.234, P _{heterogeneity}?=?0.001; P?=?0.259; for recessive model: OR?=?1.242, 95 % CI?=?0.941–1.641, P _{heterogeneity}?=?0.000; P?=?0.126; for allele comparison model: OR?=?1.096, 95 % CI?=?0.976–1.230, P _{heterogeneity}?=?0.000; P?=?0.121). In the subgroup analysis by controls source, the same results were found in all genetic models. In summary, this meta-analysis suggests that the COMT Val158Met polymorphism is not a risk factor for breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well-matched controls are warranted to confirm this finding.     

Lack of Associations of the COMT Val158Met Polymorphism with Risk of Endometrial and Ovarian Cancer: a Pooled Analysis of Case-control Studies

This meta-analysis was conducted to examine whether the genotype status of Val158Met polymorphism in catechol-O-methyltransferase (COMT) is associated with endometrial and ovarian cancer risk. Eligible studies were identified by searching several databases for relevant reports published before January 1, 2014. Pooled odds ratios (ORs) were appropriately derived from fixed-effects or random-effects models. In total, 15 studies (1,293 cases and 2,647 controls for ovarian cancer and 2,174 cases and 2,699 controls for endometrial cancer)were included in the present meta-analysis. When all studies were pooled into the meta-analysis, there was no evidence for significant association between COMT Val158Met polymorphism and ovarian cancer risk (Val/Met versus Val/Val: OR=0.91, 95% CI=0.76-1.08; Met/Met versus Val/Val: OR=0.90, 95% CI=0.73-1.10; dominant model: OR=0.90, 95% CI=0.77-1.06; recessive model: OR=0.95, 95% CI=0.80-1.13). Similarly, no associations were found in all comparisons for endometrial cancer (Val/Met versus Val/Val: OR 0.97, 95% CI=0.77-1.21; Met/Met versus Val/Val: OR=1.02, 95% CI=0.73-1.42; dominant model: OR=0.98, 95% CI=0.77-1.25; recessive model: OR=1.02, 95% CI=0.87-1.20). In the subgroup analyses by source of control and ethnicity, no significant associations were found in any subgroup of population. This meta-analysis strongly suggests that COMT Val158Met polymorphism is not associated with increased endometrial and ovarian cancer risk.     

Increasingly strong reduction in breast cancer mortality due to screening

Background:

Favourable outcomes of breast cancer screening trials in the 1970s and 1980s resulted in the launch of population-based service screening programmes in many Western countries. We investigated whether improvements in mammography and treatment modalities have had an influence on the effectiveness of breast cancer screening from 1975 to 2008.

Methods:

In Nijmegen, the Netherlands, 55 529 women received an invitation for screening between 1975 and 2008. We designed a case–referent study to evaluate the impact of mammographic screening on breast cancer mortality over time from 1975 to 2008. A total number of 282 breast cancer deaths were identified, and 1410 referents aged 50–69 were sampled from the population invited for screening. We estimated the effectiveness by calculating the odds ratio (OR) indicating the breast cancer death rate for screened vs unscreened women.

Results:

The breast cancer death rate in the screened group over the complete period was 35% lower than in the unscreened group (OR=0.65; 95% CI=0.49–0.87). Analysis by calendar year showed an increasing effectiveness from a 28% reduction in breast cancer mortality in the period 1975–1991 (OR=0.72; 95% CI=0.47–1.09) to 65% in the period 1992–2008 (OR=0.35; 95% CI=0.19–0.64).

Conclusion:

Our results show an increasingly strong reduction in breast cancer mortality over time because of mammographic screening.     

Genetic variation in PRL and PRLR, and relationships with serum prolactin levels and breast cancer risk: results from a population-based case-control study in Poland

Introduction

Studies suggest that high circulating levels of prolactin increase breast cancer risk. It is unclear if genetic variations in prolactin (PRL) or prolactin receptor (PRLR) genes also play a role. Thus, we examined the relationship between single nucleotide polymorphisms (SNPs) in PRL and PRLR, serum prolactin levels and breast cancer risk in a population-based case-control study.

Methods

We genotyped 8 PRL and 20 PRLR tag SNPs in 1965 breast cancer cases and 2229 matched controls, aged 20-74, and living in Warsaw or Łódź, Poland. Serum prolactin levels were measured by immunoassay in a subset of 773 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) for genotype associations with breast cancer risk were estimated using unconditional logistic regression, adjusted for age and study site. Geometric mean prolactin levels were estimated using linear regression models adjusted for age, study site, blood collection time, and menstrual cycle day (premenopausal women).

Results

Three SNPs were associated with breast cancer risk: in premenopausal women, PRLR rs249537 (T vs. C per-allele OR 1.39, 95% CI 1.07 - 1.80, P = 0.01); and in postmenopausal women, PRLR rs7718468 (C vs. T per-allele OR 1.16, 95% CI 1.03 - 1.30, P = 0.01) and PRLR rs13436213 (A vs. G per-allele OR 1.13 95% CI 1.01 - 1.26, P = 0.04). However, mean serum prolactin levels for these SNPs did not vary by genotype (P-trend > 0.05). Other SNPs were associated with serum prolactin levels: PRLR rs62355518 (P-trend = 0.01), PRLR rs10941235 (P-trend = 0.01), PRLR rs1610218 (P-trend = 0.01), PRLR rs34024951 (P-trend = 0.02), and PRLR rs9292575 (P-trend = 0.03) in premenopausal controls and PRL rs849872 (P-trend = 0.01) in postmenopausal controls.

Conclusions

Our data provide limited support for an association between common variations in PRLR and breast cancer risk. Altered serum prolactin levels were not associated with breast cancer risk-associated variants, suggesting that common genetic variation is not a strong predictor of prolactin-associated breast cancer risk in this population.     

Vitamin D Receptor Poly(A) Microsatellite Polymorphism and 25-Hydroxyvitamin D Serum Levels: Association with Susceptibility to Breast Cancer

Purpose

According to previous studies, vitamin D exhibits protective effects against breast cancer via the vitamin D receptor (VDR). There is growing evidence that breast cancer incidence is associated with various polymorphisms of the VDR gene. This study investigates the association of VDR poly(A) microsatellite variants with 25-hydroxyvitamin D (25(OH)D) serum levels and breast cancer risk.

Methods

Polymorphism analysis was performed on a total of 261 blood samples, which were collected from 134 women with breast cancer and 127 controls. Single strand conformation polymorphism was assessed by polymerase chain reaction in combination with sequencing to detect poly(A) lengths for each sample. The vitamin D levels of samples were determined by electrochemiluminescence.

Results

The poly(A) variant L allele frequency was significantly higher in cancer patients than in controls (odds ratio [OR], 1.73; 95% confidence interval [CI], 1.16-2.57; p=0.006). Thus, carriers of the L allele (LS and LL genotypes) have a higher risk for breast cancer (OR, 1.86; 95% CI, 1.13-3.05; p=0.013). A larger increase in the risk for breast cancer was found in individuals with the L carrier genotype and lowered 25(OH)D levels.

Conclusion

The results primarily suggest that VDR gene polymorphism in the poly(A) microsatellite is associated with 25(OH)D levels and that it can affect the breast cancer risk in the female population from northern Iran.     

Endogenous sex steroids in premenopausal women and risk of breast cancer: the ORDET cohort

Introduction

Previous studies showed that higher testosterone levels are associated with greater risk of breast cancer in premenopausal women, but the literature is scant and inconsistent.

Methods

In a prospective nested case-control study of 104 premenopausal women with incident breast cancer and 225 matched controls, all characterized by regular menstrual cycles throughout their lifetime, we measured the concentration of estradiol, total and free testosterone (FT), progesterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in blood samples collected on days 20 through 24 of their cycles.

Results

In logistic regression models, the multivariate odds ratios (ORs) of invasive breast cancer for women in the highest tertile of circulating FT compared with the lowest was 2.43 (95% confidence interval (95% CI), 1.15 to 5.10; P_trend = 0.03), whereas for total testosterone, the association had the same direction but was not statistically significant (OR, 1.27; 95% CI, 0.62 to 2.61; P_trend = 0.51). Endogenous progesterone was not statistically associated with breast cancer (OR, 1.16; 95% CI, 0.60 to 2.27; P_trend = 0.75), nor were the other considered hormones.

Conclusions

Consistent with previous prospective studies in premenopausal women and our own earlier investigation, we observed that higher levels of FT are positively associated with breast cancer risk in women with regular menstrual cycles throughout their lifetimes. No evidence of risk was found associated with the other endogenous sex steroids.     

Sunlight Exposure and Breast Density: A Population-Based Study

Purpose

This study aims to assess the association of sunlight exposure with breast cancer risk, measured by the breast density assessed from Tabár''s mammographic pattern in Chinese women.

Methods

A total of 676 premenopausal women were recruited to participate in this study, in which 650 completed a validated sunlight exposure questionnaire via telephone. The mammograms were classified according to Tabár''s classification for parenchyma, and patterns IV & V and I, II & III indicated respectively high and low risk mammographic patterns for breast cancer. The odds ratios (OR) and 95% confidence intervals (CIs) for sun exposure-related variables were estimated using unconditional logistic regression with adjustment for potential confounders.

Results

Among 646 participants, women with high breast cancer risk (Tabár''s patterns IV &V) had less hours spent in the sun than those with low risk (I, II & III) at any age stage. A higher level of sunlight exposure was associated with a significantly lower risk having high risk Tabár''s pattern. Women aged 40 to 44 years who were in the highest tertile of lifetime total hours spent in the sun had a multi-adjusted OR of 0.41 (95% CI, 0.18-0.92; p for trend=0.03) compared with those in the lowest tertile (>2.19 hr/day vs. <1.32 hr/day). For hours spent in the sun across the ages of 6 to 12 years, the comparable OR was 0.37 (95% CI, 0.15-0.91; p for trend=0.03).

Conclusion

These findings suggest that higher sunlight exposure is related to a lower risk of having high risk breast density pattern in premenopausal women. Our results also suggest the most relevant period of exposure is during earlier life.     

CD133 overexpression correlates with clinicopathological features of gastric cancer patients and its impact on survival: A systematic review and meta-analysis

Background

CD133 is one of the most commonly used markers of cancer stem cells (CSCs), which are characterized by their ability for self-renewal and tumorigenicity. However, the clinical and prognostic significance of CD133 in gastric cancer remains controversial. To clarify a precise determinant of the clinical significance of CD133, we conducted a systematic review and meta-analysis to elucidate the correlation of CD133 overexpression with prognosis and clinicopathological features of GC patients.

Methods

A search in the Cochrane Library, Pubmed, Medline, Web of Knowledge and Chinese CNKI, CBM (up to Jun 30, 2015) was performed using the following keywords gastric cancer, CD133, AC133, prominin-1, etc. Electronic searches were supplemented by hand searching reference lists, abstracts and proceedings from meetings. Outcomes included overall survival and various clinicopathological features. Two reviewers independently screened the literature according to the inclusion and exclusion criteria, extracted the data, and assessed the methodological quality of the included studies, and then RevMan 5.2.0 software was used for meta-analysis.

Results

A total of 603 gastric cancer patients from 8 studies were included. The results of the meta-analyses showed that, there were significant differences of CD133 expression in the following comparisons: gastric cancer tissues vs. normal esophageal tissue (OR = 3.49, 95% CI [2.48, 490], P < 0.00001), lymph node metastasis vs. non-lymph node metastasis (OR = 2.75, 95% CI [1.99, 3.81], P < 0.00001), distant metastasis vs. non-distant metastasis (OR = 2.38, 95%CI [1.47, 3.85], P < 0.0004), clinical stages III~IV vs. clinical stages I~II (OR = 2.83, 95% CI [2.13, 3.76], P < 0.00001), as well as the accumulative 5-year overall survival rates of CD133-positive vs. CD133-negative patients (OR = 0.23, 95% CI [0.16, 0.33], P < 0.00001).

Conclusion

Overexpression of CD133 is associated with lymph node metastasis, distant metastasis, poor TNM stage. Additionally, CD133-positive gastric cancer patients had worse prognosis. Our results indicate that CD133 may be involved in the carcinogenesis of gastric cancer. Evaluation of cytoplasmic CD133 overexpression in gastric cancer tissue sections may be useful in the future as a novel prognostic factor. Nevertheless, due to the poor quality and small sample size of included trials, more well-designed multi-center randomized controlled trials should be performed.     

Evaluation of variation in the phosphoinositide-3-kinase catalytic subunit alpha oncogene and breast cancer risk

Background:

Somatic mutations in phosphoinositide-3-kinase catalytic subunit alpha (PIK3CA) are frequent in breast tumours and have been associated with oestrogen receptor (ER) expression, human epidermal growth factor receptor-2 overexpression, lymph node metastasis and poor survival. The goal of this study was to evaluate the association between inherited variation in this oncogene and risk of breast cancer.

Methods:

A single-nucleotide polymorphism from the PIK3CA locus that was associated with breast cancer in a study of Caucasian breast cancer cases and controls from the Mayo Clinic (MCBCS) was genotyped in 5436 cases and 5280 controls from the Cancer Genetic Markers of Susceptibility (CGEMS) study and in 30 949 cases and 29 788 controls from the Breast Cancer Association Consortium (BCAC).

Results:

Rs1607237 was significantly associated with a decreased risk of breast cancer in MCBCS, CGEMS and all studies of white Europeans combined (odds ratio (OR)=0.97, 95% confidence interval (CI) 0.95–0.99, P=4.6 × 10⁻³), but did not reach significance in the BCAC replication study alone (OR=0.98, 95% CI 0.96–1.01, P=0.139).

Conclusion:

Common germline variation in PIK3CA does not have a strong influence on the risk of breast cancer