Breast cancer susceptibility loci in association with age at menarche,age at natural menopause and the reproductive lifespan

Background: Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) associated with breast cancer risk. Some of these loci have unknown functional significance and may mediate the effects of hormonal exposures on breast cancer risk. We examined relationships between breast cancer susceptibility variants and menstrual/reproductive factors using data from two population-based studies. Methods: The first analysis was based on a sample of 1328 women age 20–74 who participated as controls in a case–control study of breast cancer conducted in three U.S. states. We evaluated the associations between age at menarche, age at natural menopause and the reproductive lifespan with 13 previously identified breast cancer variants. Associations were also examined with a genetic score created as the sum of at-risk alleles across the 13 variants. For validation, significant results were evaluated in a second dataset comprised 1353 women age 43–86 recruited as part of a cohort study in Wisconsin. Results: Neither the genetic score nor any of the 13 variants considered individually were associated with age at menarche or reproductive lifespan. Two SNPs were associated with age at natural menopause; every increase in the minor allele (A) of rs17468277 (CASP8) was associated with a 1.12 year decrease in menopause age (p = 0.02). The minor allele (G) of rs10941679 (5p12) was associated with a 1.01 year increase in age at natural menopause (p = 0.01). The results were not replicated in the validation cohort (B = −0.61, p = 0.14 and B = −0.01, p = .0.98, respectively). Conclusions: The evaluated variants and reproductive experiences may work through separate pathways to influence breast cancer risk.     

Do adipokines underlie the association between known risk factors and breast cancer among a cohort of United States women?

Introduction: Obesity is a well-established risk factor for postmenopausal breast cancer, but mechanisms underlying the association are unclear. Adipocyte-derived, cytokine-like adipokines have been suggested as contributory factors. To evaluate their association with breast cancer risk factors and breast cancer risk, we conducted a nested case-control study of 234 postmenopausal breast cancer cases and 234 controls in a cohort of U.S. women with prospectively-collected serum samples obtained in the mid 1970s and followed for up to 25 years. Methods: Adiponectin, absolute plasminogen activator inhibitor-1 (aPAI-1), and resistin were measured by a multiplex immunoassay. Sex hormones were available for 67 cases and 67 controls. Results: Among controls, we found that lower levels of adiponectin and higher levels of aPAI-1 were correlated with increasing levels of estradiol (Spearman r = ?0.26, p-value = 0.033; r = 0.42, p = 0.0003), decreasing levels of sex hormone binding globulin (r = 0.38, p = 0.0013; r = ?0.32, p = 0.0076), and increasing body mass index (BMI) (r = ?0.31, p =  < 0.0001; r = 0.39, p =  < 0.0001). Hormones were not associated with resistin. Among the relatively small percentage of women using postmenopausal hormones at the time of blood collection (13.7%), aPAI-1 levels were higher than in non-users (p = 0.0054). Breast cancer risk was not associated with circulating levels of adiponectin (age-adjusted p for linear trend = 0.43), aPAI-1 (p = 0.78), or resistin (p = 0.91). The association was not confounded by BMI, parity, age at first full-term birth, age at menopause, current postmenopausal hormone use, and circulating sex steroid hormones. Furthermore, adipokine associations were not modified by BMI (p > 0.05). The lack of association with risk may be due to measurement error of the laboratory assays. Discussion: lower levels of adiponectin and higher levels of aPAI-1 measured in prospectively-collected serum from postmenopausal women were associated with increasing BMI but not breast cancer risk.     

Polymorphisms of the NOS3 gene and risk of myocardial infarction in the Tunisian population

Controversial results regarding the association of eNOS gene (NOS3) polymorphisms with myocardial infarction (MI) have been reported. This study investigated the relationship of the −786T>C (rs2070744), 894G>T (rs1799983) and 4a4b polymorphisms of the NOS3 gene with the presence of MI in the Tunisian population. In addition, we also examined the association of NOS3 gene haplotypes with MI in Tunisian subjects.A total of 303 patients with MI and 225 controls were included in the study. The 894G>T and −786T>C single nucleotide polymorphisms were analyzed by PCR-RFLP, and 4a4b polymorphism just for PCR.There was significant linkage disequilibrium between the three NOS3 polymorphisms (p < 0.0001). The genotype distribution and allele frequency of NOS3 4a4b, but not −786T>C and 894G>T, polymorphism was significantly different between MI patients and controls. The univariate logistic regression analysis showed a significant association of the 4a4b polymorphism and MI according to co-dominant, dominant and recessive models (co-dominant model OR: 4.38, 95%CI: 1.24–15.41; p = 0.021, dominant model OR: 1.66, 95%CI: 1.14–2.42); p = 0.007, and recessive model OR: 3.85, 95%CI: 1.10–13.47; p = 0.035). The multivariate analysis, adjusted for traditional cardiovascular risk factors, revealed that the NOS3 4a4a genotype was an independent predisposing factor to MI, according to the models considered. In addition, a haplotype 7 (C-T-4a), (OR = 12.05, p = 0.010) was a risk factor of MI after controlling for classical risk factors.These finding suggest that the 4a4b polymorphism of the NOS3 gene was associated with MI in Tunisian patients.     

Does consanguinity lead to decreased incidence of breast cancer?

Background: In the Middle East region, consanguinity remains to be a central feature where it has shown an increasing trend. Breast cancer is an extremely complex disease, characterized by a progressive multistep process caused by interactions of both environmental and genetic factors. Aim: The aim of this study was to examine the possible effect of consanguinity on the risk of breast cancer in a population with a high rate of consanguinity and find the associated risk-modifying factors. Subjects and methods: The study included 167 Qatari and other Arab expatriates women with breast cancer and 341 age and ethnicity matched control women. A questionnaire that included the socio-demographic information, type of consanguinity, medical history, life style habits, dietary intake and tumor grade was designed to collect, the information of cases and controls. A total number of 214 breast cancer patients were approached and 167 cases completed the questionnaires with a response rate of 78%. Of the 417 healthy women who agreed to participate in this study, 341 responded to the questionnaire (81.8%). Results: The study revealed that the rate of parental consanguinity was lower in breast cancer patients (24%) than in controls (32.3%) (p = 0.062). Female controls were slightly younger (46.5 ± 11.9) than breast cancer patients (48.4 ± 10.7). Breast cancer incidence was significantly higher in Qatari women (34.1%) compared to other Arab women (65.9%) (p = 0.034). A significant difference was noted only in occupation of the studied women between cases and controls (p < 0.001). Overweight (46.7%) and obesity (32.9%) were significantly higher in female breast cancer patients compared to controls (p = 0.028). Overall, the mean coefficient of consanguinity was lower in breast cancer patients (0.014) than in controls (0.018) (p = 0.0125). Family history of breast cancer was significantly more often in breast cancer patients (14.4%) than in controls (6.2%) (p = 0.002). However, the family history of breast cancer was more often positive in cases of non-consanguineous parents (15.7%) than cases of consanguineous parents (10.0%). Conclusion: The present study revealed the lack of association between of breast cancer and the parental consanguinity in Arab women residing in Qatar. The family history of breast cancer and the body mass index (BMI) are highly associated with breast cancer.     

Association of TP53 codon 72 and CDH1 genetic polymorphisms with colorectal cancer risk in Bangladeshi population

Till now no pharmacogenetic study of TP53 codon 72 (Arg72Pro) and CDH1 rs16260 (-160C<A) genes has been reported on Bangladeshi population relating those with colorectal cancer. So the aim of the study is to determine whether there is an elevated risk of colorectal cancer development with TP53 codon 72 and CDH1 rs16260 genetic polymorphism in Bangladeshi population for the first time. To investigate the association of these two SNPs, we conducted a case-control study with 288 colorectal cancer patients and 295 healthy volunteers by using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. We found an increased risk of association between Arg/Pro heterozygosity (adjusted OR = 2.58, 95% CI = 1.77–3.77, p < 0.05) and Pro/Pro mutant homozygosity (adjusted OR = 2.92, 95% CI = 1.78–4.78, p < 0.05) along with the combined genotype (Arg/Pro + Pro/Pro) (adjusted OR = 2.70, 95% CI = 1.90–3.82, p < 0.05) and colorectal cancer predisposition. In case of CDH1 rs16260 polymorphism, C/A heterozygous and A/A mutant homozygous are significantly (p < 0.05) found to be associated with colorectal cancer risk with adjusted OR of 1.94 and 2.63, respectively. The combined genotype of C/A and A/A was also found to be strongly associated with colorectal cancer risk compared to C/C genotype (adjusted OR = 2.02, 95% CI = 1.42–2.87, p < 0.05). In conclusion, heterozygosity and mutant homozygosity as well as the combination of both TP53 Arg72Pro and CDH1 rs16260 polymorphisms are responsible to increase the risk of colorectal cancer development in Bangladeshi population.     

Birth weight and subsequent risk of cancer

Background: We aimed to determine the association between self-reported birth weight and incident cancer in the Women's Health Initiative Observational Study cohort, a large multiethnic cohort of postmenopausal women. Methods: 65,850 women reported their birth weight by category (<6 lbs, 6–7 lbs 15 oz, 8–9 lbs 15 oz, and ≥10 lbs). All self-reported, incident cancers were adjudicated by study staff. We used Cox proportional hazards regression to estimate crude and adjusted hazard ratios (aHR) for associations between birth weight and: (1) all cancer sites combined, (2) gynecologic cancers, and (3) several site-specific cancer sites. Results: After adjustments, birth weight was positively associated with the risk of lung cancer (p = 0.01), and colon cancer (p = 0.04). An inverse trend was observed between birth weight and risk for leukemia (p = 0.04). A significant trend was not observed with breast cancer risk (p = 0.67); however, women born weighing ≥10 lbs were less likely to develop breast cancer compared to women born between 6 lbs-7 lbs 15 oz (aHR 0.77, 95% CI 0.63, 0.94). Conclusion: Birth weight category appears to be significantly associated with the risk of any postmenopausal incident cancer, though the direction of the association varies by cancer type.     

Assessment of women's risk factors for breast cancer and predictors of the practice of breast examination in two rural areas near Ibadan,Nigeria

Objective: In Nigeria, breast cancer is the most common cancer among women in majority of the regions. Late presentation has also been reported for about four decades. This study assessed the women's risk factors for breast cancer and predictive factors for the practice of breast examinations. The findings will be of help in enhancing early detection of the disease and reducing mortality from the disease. Methods: Utilizing a multi-stage sampling method, 420 women were selected at Akinyele Local government area of Ibadan. Data was collected with questionnaire. The risk factor was evaluated using the breast cancer risk assessment tool based on the Gail model. Six demographic factors, plus four covariates: knowledge of BSE/CBE, knowledge of the cause of, symptoms and signs of and treatment of breast cancer, were regressed against two dependent variables of practice of BSE and CBE using linear regression and binary logistic analyses respectively. Results: Only 386 questionnaires properly filled were analyzed. The mean age of respondents was 37.3 (SD = 13.1) years. They were of low educational status and were mostly traders and married. Only 190 of the women fulfilled the criteria for assessment with the Gail model. Most of the women, 180 (94.7%), had five years and 184 (96.8%) had lifetime risks lower than that of the average woman of the same age. Four significant predictors of BSE were marital status (p = 0.004), educational status (p = 0.018), knowledge of treatment of breast cancer (p = 0.029) and knowledge of BSE/CBE (p = 0.0001) while no formal education status and being a farmer were the only significant predictors of CBE. Conclusions: The findings are useful for planning interventional studies to enhance early detection in a low resource country.     

Diabetes,physical activity and breast cancer among Hispanic women

Purpose: We assessed the association between diabetes and breast cancer and whether physical activity modified the effect of diabetes on breast cancer in Hispanic women. Methods: We used data from a case-control study of breast cancer among Hispanic women aged 30–79 conducted between 2003 and 2008 on the Texas–Mexico border. In-person interviews were completed with 190 incident breast cancer cases ascertained through surgeons and oncologists, and 979 controls who were designated as both high-risk (n = 511) and low-risk (N = 468) for breast cancer (with respective response rates of 97%, 83% and 74%). Results: After adjustment for menopausal status and mammography screening, there was no effect of diabetes on breast cancer risk (high-risk control group odds ratio [OR] 1.02, 95% confidence interval [CI] 0.71–1.48; low-risk control group OR 0.87, 0.58–1.30). Women who had a diabetes history and did not exercise were at no risk of breast cancer (OR 0.96, 95% CI 0.63–1.48) or a slightly reduced breast cancer risk (low-risk control group OR 0.72, 95% CI 0.46–1.15) depending on the control group used, while women with diabetes who did exercise had significantly reduced breast cancer risk (OR 0.41, 95% CI 0.21–0.83) regardless of the control group used (high-risk control group p-value for interaction = 0.013, low-risk control group p-value for interaction 0.183). Conclusions: Should other studies confirm our results, physical activity should be explored as a means of reducing breast cancer risk in diabetic women.     

Breast cancer detection risk in screening mammography after a false-positive result

Background: False-positives are a major concern in breast cancer screening. However, false-positives have been little evaluated as a prognostic factor for cancer detection. Our aim was to evaluate the association of false-positive results with the cancer detection risk in subsequent screening participations over a 17-year period. Methods: This is a retrospective cohort study of 762,506 women aged 45–69 years, with at least two screening participations, who underwent 2,594,146 screening mammograms from 1990 to 2006. Multilevel discrete-time hazard models were used to estimate the adjusted odds ratios (OR) of breast cancer detection in subsequent screening participations in women with false-positive results. Results: False-positives involving a fine-needle aspiration cytology or a biopsy had a higher cancer detection risk than those involving additional imaging procedures alone (OR = 2.69; 95%CI: 2.28–3.16 and OR = 1.81; 95%CI: 1.70–1.94, respectively). The risk of cancer detection increased substantially if women with cytology or biopsy had a familial history of breast cancer (OR = 4.64; 95%CI: 3.23–6.66). Other factors associated with an increased cancer detection risk were age 65–69 years (OR = 1.84; 95%CI: 1.67–2.03), non-attendance at the previous screening invitation (OR = 1.26; 95%CI: 1.11–1.43), and having undergone a previous benign biopsy outside the screening program (OR = 1.24; 95%CI: 1.13–1.35). Conclusion: Women with a false-positive test have an increased risk of cancer detection in subsequent screening participations, especially those with a false-positive result involving cytology or biopsy. Understanding the factors behind this association could provide valuable information to increase the effectiveness of breast cancer screening.     

Rhomboid domain containing 2 (RHBDD2): A novel cancer-related gene over-expressed in breast cancer

In the course of breast cancer global gene expression studies, we identified an uncharacterized gene known as RHBDD2 (Rhomboid domain containing 2) to be markedly over-expressed in primary tumors from patients with recurrent disease. In this study, we identified RHBDD2 mRNA and protein expression significantly elevated in breast carcinomas compared with normal breast samples as analyzed by SAGE (n = 46) and immunohistochemistry (n = 213). Interestingly, specimens displaying RHBDD2 over-expression were predominantly advanced stage III breast carcinomas (p = 0.001). Western-blot, RT-PCR and cDNA sequencing analyses allowed us to identify two RHBDD2 alternatively spliced mRNA isoforms expressed in breast cancer cell lines. We further investigated the occurrence and frequency of gene amplification and over-expression affecting RHBDD2 in 131 breast samples. RHBDD2 gene amplification was detected in 21% of 98 invasive breast carcinomas analyzed. However, no RHBDD2 amplification was detected in normal breast tissues (n = 17) or breast benign lesions (n = 16) (p = 0.014). Interestingly, siRNA-mediated silencing of RHBDD2 expression results in a decrease of MCF7 breast cancer cells proliferation compared with the corresponding controls (p = 0.001). In addition, analysis of publicly available gene expression data showed a strong association between high RHBDD2 expression and decreased overall survival (p = 0.0023), relapse-free survival (p = 0.0013), and metastasis-free interval (p = 0.006) in patients with primary ER-negative breast carcinomas. In conclusion, our findings suggest that RHBDD2 over-expression behaves as an indicator of poor prognosis and may play a role facilitating breast cancer progression.     

Tumor characteristics and family history in relation to mammographic density and breast cancer: The French E3N cohort

BackgroundMammographic density is a known heritable risk factor for breast cancer, but reports how tumor characteristics and family history may modify this association are inconsistent.MethodsDense and total breast areas were assessed using Cumulus™ from pre-diagnostic mammograms for 820 invasive breast cancer cases and 820 matched controls nested within the French E3N cohort study. To allow comparisons across models, percent mammographic density (PMD) was standardized to the distribution of the controls. Odds ratios (OR) and 95% confidence intervals (CI) of breast cancer risk for mammographic density were estimated by conditional logistic regression while adjusting for age and body mass index. Heterogeneity according to tumor characteristic and family history was assessed using stratified analyses.ResultsOverall, the OR per 1 SD for PMD was 1.50 (95% CI, 1.33–1.69). No evidence for significant heterogeneity by tumor size, lymph node status, grade, and hormone receptor status (estrogen, progesterone, and HER2) was detected. However, the association of PMD was stronger for women reporting a family history of breast cancer (OR_1SD = 2.25; 95% CI, 1.67–3.04) than in women reporting none (OR_1SD = 1.41; 95% CI, 1.24–1.60; p_{heterogeneity} = 0.002). Similarly, effect modification by FHBC was observed using categories of PMD (p_{heterogeneity} = 0.02) with respective ORs of 15.16 (95% CI, 4.23–54.28) vs. 3.14 (95% CI, 1.89–5.22) for ≥50% vs. <10% PMD.ConclusionsThe stronger association between mammographic density and breast cancer risk with a family history supports the hypothesis of shared genetic factors responsible for familial aggregation of breast cancer and the heritable component of mammographic density.     

Functional polymorphisms in the IL6 gene promoter and the risk of urinary bladder cancer in India

BackgroundInterleukin-6 is a multifunctional cytokine, which plays a key role in tumor proliferation and differentiation. Variations in its gene (IL6) sequence may affect the risk of developing various cancers, including urinary bladder cancer. The present study was done to find the association of functional polymorphisms in the IL6 promoter with urinary bladder cancer.Materials and methodsSingle nucleotide polymorphisms were genotyped in histologically confirmed 232 cases of urinary bladder cancer and 250 healthy controls. The controls subjects were matched to the cases by age, sex, and ethnicity. Genotyping of the polymorphisms (−174G>C; −572G>C, −596A>G) was undertaken by direct DNA sequencing. The level of association between the genotypes and urinary bladder cancer risk was estimated by odds ratios and 95% confidence intervals generated by applying the chi-square test. Linkage disequilibrium (LD) between SNPs and haplotype analysis were performed using Haploview software.ResultSignificantly higher number of smokers (p = 0.047), tobacco chewers (p = <0.001) and those with non-vegetarian food habits (p = 0.016) were seen in the case group. The distribution of genotypes at −174G>C locus differed significantly between cases and controls and the variant genotypes GC + CC were significantly rarer in the cases (p = 0.00073; OR = 0.52 95% CI 0.35–0.75). Variant genotypes (GC + CC) were more common in grade I than grade III tumors (p = 0.032), further suggesting a protective effect. No LD was found between the SNPs; however, the frequency of haplotype AGC was significantly lesser in the cases than controls (p = 0.0103), suggesting a protective effect. Genotype distribution at the other two loci (−572G>C and −596A>G) did not show association with bladder cancer.ConclusionsIL6 (−174G>C) substitution confers significant protection against the risk of urinary bladder cancer in the study population, while other substitutions in this gene (−572G>C and −596A>G) do not affect the risk. In general, there is a lack of studies on the cytokine gene polymorphisms in urinary bladder cancer.     

Distribution of TYMS,MTHFR, p53 and MDR1 gene polymorphisms in patients with breast cancer treated with neoadjuvant chemotherapy

Purpose To investigate the role of TSER (TYMS), C677T (MTHFR), Arg72Pro (p53) and C3435T (MDR1) gene polymorphisms in breast cancer patients treated with 5-fluorouracil and cyclophosphamide-based neoadjuvant chemotherapy. Results Observed allelic frequencies were: TSER, (2) 0.54 and (3) 0.46; MTHFR C677T, (C) 0.59 and (T) 0.41; p53 Arg72Pro, (Arg) 0.73 and (Pro) 0.27; MDR1 C3435T, (C) 0.52 and (T) 0.48. MTHFR allele T and p53 allele Pro were strongly associated with toxicity due to chemotherapy (odds ratio, 7.1 (95% confidence interval, 1.4–36.1; p = 0.018) and 7.0 (95% confidence interval, 1.2–40.5; p = 0.029), respectively). Conclusion We introduced new data related to the contribution of p53 codon 72 to toxicity due to 5-fluorouracil and cyclophosphamide-based neoadjuvant chemotherapy in patients with breast cancer.     

Association between TNF-α-308 G/A gene polymorphism and gastric cancer risk: A systematic review and meta-analysis

ObjectiveTumor necrosis factor-alpha (TNF-α) has been found to be associated with gastric carcinogenesis, but individually published results have been inconclusive. The aim of this study was to explore the relationship between the TNF-α-308 G/A polymorphism and gastric cancer risk.MethodsMEDLINE, EMBASE and the COCHRANE library databases were searched for relevant articles to identify all available data. The odds ratios (ORs) with 95% confidence intervals (95% CIs) from each study were used to assess the association between the TNF-α-308 G/A polymorphism and gastric cancer risk.ResultsThis meta-analysis included 30 studies (32 datasets) involving 7009 gastric cancer cases and 12,119 control subjects. Overall, a significant association was found between the TNF-α-308 G/A polymorphism and gastric cancer in AA + GA vs. GG (dominant contrast model) (OR = 1.20, 95% CI = 1.07–1.34, p = 0.001). With stratification based on ethnicity, the TNF-α-308 G/A polymorphism was correlated with gastric cancer risk in Caucasians, using the dominant contrast model (OR = 0.74, 95% CI = 0.57–0.96, p = 0.02), but not in East Asians and other ethnic groups. In the comprehensive subgroup analysis, a significant association was also found in recent articles (published after 2005), population-based high-quality studies, hospital-based high-quality studies, studies using the TaqMan method and non-cardia subgroups. However, the TNF-α-308 G/A polymorphism was not associated with specific histological types of gastric cancer risk.ConclusionsThe TNF-α-308 G/A polymorphism may contribute to susceptibility to gastric cancer in Caucasians, especially for non-cardia gastric cancer, as most strongly demonstrated in high-quality studies and in studies using the TaqMan genotyping method. Furthermore, we recommend the TaqMan method as the preferred genotyping method in DNA polymorphism studies.     

Association between periodontitis and common variants in the promoter of the interleukin-6 gene

We recently reported an association between interleukin-6 (IL6) polymorphisms (SNPs) and haplotypes and aggressive periodontitis (AgP). The aim of this study was to investigate this association in a larger cohort of subjects, affected by either aggressive or chronic periodontitis. Five IL6 SNPs were analyzed in 765 subjects (167 generalized aggressive periodontitis, 57 localized aggressive, 310 chronic periodontitis and 231 periodontally healthy). Among Caucasians (n = 454) there were moderate associations for ?1363T allele (p = 0.011) and for ?174GG and ?1363GG genotypes with diagnosis of periodontitis (respectively, p = 0.044, OR = 1.6, 95% CI = 1.0–2.4, and p = 0.017, OR = 1.8, 95% CI = 1.1–2.8, adjusted for age, gender and smoking). Haplotypes containing the ?174G>C, ?1363G>T and ?1480C>G polymorphisms were associated with diagnosis of periodontitis (p = 0.02). Subgroup analysis by disease phenotype showed associations for the localized AgP (LAgP) group and ?1480C>G and ?6106A>T SNPs (p = 0.007 and 0.010, respectively). Among Caucasians the genotypes IL6 ?1480 CC and ?6106 TT increased the adjusted OR for LAgP (OR = 3.09 and 2.27, respectively). This study supports the hypothesis that IL6 polymorphisms and haplotypes are moderately associated with periodontitis, possibly acting through influencing tissue levels of IL6. This association is stronger for LAgP than for other periodontal disease phenotypes.     

Associations of body mass index with cancer incidence among populations,genders, and menopausal status: A systematic review and meta-analysis

In order to further reveal the differences of association between body mass index (BMI) and cancer incidence across populations, genders, and menopausal status, we performed comprehensive meta-analysis with eligible citations. The risk ratio (RR) of incidence at 10 different cancer sites (per 5 kg/m² increase in BMI) were quantified separately by employing generalized least-squares to estimate trends, and combined by meta-analyses. We observed significantly stronger association between increased BMI and breast cancer incidence in the Asia⿿Pacific group (RR 1.18:1.11⿿1.26) than in European⿿Australian (1.05:1.00⿿1.09) and North-American group (1.06:1.03⿿1.08) (meta-regression p < 0.05). No association between increased BMI and pancreatic cancer incidence (0.94:0.71⿿1.24) was shown in the Asia⿿Pacific group (meta-regression p < 0.05), whereas positive associations were found in other two groups. A significantly higher RR in men was found for colorectal cancer in comparison with women (meta-regression p < 0.05). Compared with postmenopausal women, premenopausal women displayed significantly higher RR for ovarian cancer (pre- vs. post- = 1.10 vs. 1.01, meta-regression p < 0.05), but lower RR for breast cancer (pre- vs. post- = 0.99 vs. 1.11, meta-regression p < 0.0001). Our results indicate that overweight or obesity is a strong risk factor of cancer incidence at several cancer sites. Genders, populations, and menopausal status are important factors effecting the association between obesity and cancer incidence for certain cancer types.     

Prolonged breastfeeding reduces risk of breast cancer in Sri Lankan women: A case–control study

Goal: To assess the association between duration of breastfeeding and the risk of breast cancer in Sri Lankan women. Methods: We conducted a case–control study in women aged 30–64 years in selected health care facilities in the Western province. A total of 100 recent cases of breast cancer (histologically confirmed) and 203 controls (age and parity matched) were included. Detailed information regarding breastfeeding, menstruation, reproductive factors, passive smoking and other confounders was collected using a structured questionnaire. Adjusted odds ratios and 95% confidence intervals were calculated using multiple logistic regressions. Principle results: Multivariate analysis found that those women who breastfed for ≥24 months during lifetime had significantly lower risk of breast cancer than those who breastfed for less than 24 months (OR = 0.40; 95%CI = 0.22, 0.73). Compared to 0–11 months of lifetime breastfeeding, there was a 66.3% reduction in breast cancer risk in women who breastfed for 12–23 months, 87.4% reduction in 24–35 months and 94% reduction in 36–47 months categories. The mean duration of breastfeeding per child for ≥12 months was also associated with reduced risk of breast cancer (OR = 0.52; 95%CI = 0.28, 0.94). The significant factors associated with increased risk of breast cancer were: post-menopausal women (OR = 1.74; 95%CI = 1.01, 3.01); having an abortion in the past (OR = 3.42; 95%CI = 1.75, 6.66) and exposure to passive smoking (OR = 2.96, 95%CI = 1.53, 5.75). Major conclusions: Prolonged breastfeeding significantly reduces the risk of breast cancer and this protective effect was supported by a dose–response relationship. Risk due to passive smoking should be emphasized in anti-smoking programmes.     

Recreational physical activity and risk of papillary thyroid cancer among women in the California Teachers Study

Purpose: Little is known about the relationship between physical activity and thyroid cancer risk, and few cohort data on this association exist. Thus, the present study aimed to prospectively examine long-term activity and risk of papillary thyroid cancer among women. Methods: 116,939 women in the California Teachers Study, aged 22–79 years with no history of thyroid cancer at cohort entry, were followed from 1995–1996 through 2009; 275 were diagnosed with invasive papillary thyroid cancer. Cox proportional-hazards regression provided relative risk (RR) estimates and 95% confidence intervals (CI) for associations between thyroid cancer and combined strenuous and moderate recreational physical activity both in the long-term (high school through age 54 years or current age if younger than 54 years) and recently (during the three years prior to joining the cohort). Results: Overall, women whose long-term recreational physical activity averaged at least 5.5 MET-hours/week (i.e. were active) had a non-significant 23% lower risk of papillary thyroid cancer than inactive women (RR = 0.77, 95% CI: 0.57, 1.04). RR estimates were stronger among normal weight or underweight women (body mass index, BMI < 25.0 kg/m², trend p = 0.03) than among overweight or obese women (trend p = 0.35; homogeneity-of-trends p = 0.03). A similar pattern of risk was observed for recent activity (BMI < 25 kg/m², trend p = 0.11; BMI ≥ 25 kg/m², trend p = 0.16; homogeneity-of-trends p = 0.04). Associations for long-term activity did not appear to be driven by activity in any particular life period (e.g. youth, adulthood). Conclusions: Long-term physical activity may reduce papillary thyroid cancer risk among normal weight and underweight women.     

ERCC1 haplotypes modify bladder cancer risk: A case–control study

Bladder cancer risk is highly influenced by environmental and/or predisposing genetic factors. In the last decades growing evidence of the major role played by DNA repair systems in the developing of bladder cancer has been provided. To better investigate the involvement of DNA repair genes previously reported to be significantly associated with bladder cancer risk, we examined in a case–control study (456 cases and 376 hospital controls) 36 single nucleotide polymorphisms (SNPs) in 10 DNA repair genes, through a better gene coverage and a deep investigation of the haplotype role. A single SNP analysis showed a significantly increased risk given by XRCC1-rs915927 G allele (OR = 1.55, CI 95% 1.02–2.37 for dominant model) and a protective effect of the rare alleles of 3 ERCC1 SNPs: rs967591 (OR = 0.66, CI 95% 0.46–0.95), rs735482 (OR = 0.62, CI 95% 0.42–0.90) and rs2336219 (OR = 0.63, CI 95% 0.43–0.93). Haplotype analysis revealed that cases had a statistically significant excess of XRCC3-TAGT and ERCC1-GAT haplotypes, whereas ERCC1-AAC, MGMT-TA, XRCC1-TGCC and ERCC2-TGAA haplotypes were significantly underrepresented. Together with other published data on large case–control studies, our findings provide epidemiological evidence supporting a link between DNA repair gene variants and bladder cancer development, and suggest that the effects of high-order interactions should be taken into account as modulating factors affecting bladder cancer risk. A detailed characterization of DNA repair genetic variation is warranted and might ultimately help to identify multiple susceptibility variants that could be responsible for joint effects on the risk.     

Breast cancer risk and common single nucleotide polymorphisms in homologous recombination DNA repair pathway genes XRCC2, XRCC3, NBS1 and RAD51

The possible role for DNA repair deficiencies in cancer development, namely in breast cancer has been the subject of increasing interest since it has been reported that breast cancer patients might be deficient in the repair of DNA damage. Exposure to ionizing radiation has been pointed out as a risk factor for breast cancer, and the type of DNA lesions induced by this carcinogen can be repaired by homologous recombination DNA repair (HRR) pathway. To evaluate the potential modifying role of some single nucleotide polymorphisms (SNP) in HRR involved genes on the individual susceptibility to breast cancer we carried out a hospital based case–control study in a Caucasian Portuguese population (289 histological confirmed breast cancer patients and 548 control individuals). We genotyped 4 SNPs in 4 different HRR pathway genes, XRCC2 (Ex3 + 442G > A, R188H, rs3218536), XRCC3 (Ex8-5C > T, T241M, rs861539), NBS1 (Ex5-32C > G, E185Q, rs1805794) and RAD51 5′UTR (Ex1-59G > T, rs1801321), tagging 41 SNPs in these genes. The frequency of the different polymorphisms in the Portuguese control population is similar to the ones reported for other Caucasian populations, and the deviation of the Hardy–Weinberg equilibrium was only observed for the XRCC2 (Ex3 + 442G > A, R188H, rs3218536) polymorphism in the control population. The results obtained, after logistic regression analysis, did not reveal a major role of these polymorphisms on breast cancer susceptibility. However, when the population was stratified according to breast feeding (women that breast fed and women that never breast fed) it is observed, in women that never breast fed, that the heterozygous individuals for the XRCC2 (Ex3 + 442G > A, R188H, rs3218536) polymorphism have a decreased risk for breast cancer [adjusted OR = 0.45; 95% CI = 0.22–0.92] (P = 0.03). Additionally, after stratification according to menopausal status, our results suggest that post-menopausal women carrying at least one variant allele for the XRCC3 (Ex8-5C > T, T241M, rs861539) polymorphism have a lower risk for breast cancer [adjusted OR = 0.67; 95% CI, 0.47–0.94] (P = 0.03). Most of the studies suggest that breastfeeding may be responsible for 2/3 of the estimate reduction of breast cancer. The longer the duration of breastfeeding the lower the potential risk associated with breast cancer. Therefore, in our study the potential protective role of the variant allele of XRCC2 (Ex3 + 442G > A, R188H, rs3218536), in never breast fed women, might be related with a more efficient DNA repair activity.