Single nucleotide polymorphisms of the aromatase gene (CYP19A1), HER2/neu status, and prognosis in breast cancer patients

Purpose Estrogen exposure is involved in both breast cancer susceptibility and the prognosis in patients with breast cancer. Aromatase is involved in the production of estrogens, and altered expression of it might be associated with the prognosis. The aim of this study was to examine the effect of single nucleotide polymorphisms (SNPs) in the aromatase gene, CYP19A1, on the prognosis, and in relation to tumor and patient characteristics in a cohort of breast cancer patients. Patients and methods The cohort analyzed in this study consisted of 1,257 patients with invasive primary breast cancer. Polymorphisms rs10046, rs4646 and rs700519 were genotyped within this group. Results The variant genotypes of rs10046 and rs4646 were associated with a lower percentage of HER2-positive tumors. There was no association of rs700519 and rs4646 with disease-free survival (DFS) or overall survival (OS). The variant genotype of rs10046 was significantly associated with a better 5-year DFS (hazards ratio 0.51; 95% CI, 0.32 to 0.81; P = 0.004) adjusted for age, nodal status, tumor size grading, and hormone receptor status. This effect appeared to be determined in the subgroup of premenopausal patients. Conclusion SNPs rs10046 and rs4646 may influence the HER2 status of breast cancer tumors, and rs10046 genotypes are associated with an altered DFS. Genotypes of aromatase polymorphisms may influence the prognosis for breast cancer patients not only by affecting the extent of estrogen exposure but also through an alteration in tumor characteristics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A <Emphasis Type="Italic">CYP19</Emphasis> (aromatase) polymorphism is associated with increased premenopausal breast cancer risk

Due to the established association between estrogen levels and breast cancer risk, polymorphic variation in genes regulating estrogen levels is thought to be related to breast cancer risk. Aromatase, the protein product of the CYP19 gene, is involved in the production of endogenous estrogens via androgen conversion. We examined whether polymorphic variation in CYP19 associated with increased breast cancer risk in a population based case-control study. We examined two single nucleotide polymorphisms (SNP), rs1008805 (A/G) and rs730154 (C/T), which have been shown to tag SNPs within two different haplotype blocks in CYP19. Among premenopausal women, the presence of at least one G allele at rs1008805 was significantly associated with an increase in the risk of breast cancer (OR = 1.72 [95% CI, 1.20–2.49]), especially with estrogen and progesterone receptor negative breast cancer (OR = 3.89 [1.74–8.70] and OR = 2.52 [1.26–5.05], respectively). No association was observed among postmenopausal women (OR = 1.06 [0.82–1.36]). There was no significant association between rs730154 and breast cancer, regardless of menopausal status. Our results suggest that premenopausal women carrying the G allele at CYP19 rs1008805 have increased risk of breast cancer. The finding supports the potential role of variation in estrogen biosynthesis genes in premenopausal breast cancer risk.     

Association of genetic polymorphisms of <Emphasis Type="Italic">ER-α</Emphasis> and the estradiol-synthesizing enzyme genes <Emphasis Type="Italic">CYP17</Emphasis> and <Emphasis Type="Italic">CYP19</Emphasis> with breast cancer risk in Chinese women

Estrogen plays a role in breast cancer development, and genetic polymorphisms in estrogen receptor gene ER-α and genes regulating estrogen biosynthesis and metabolisms are associated with the risk of breast cancer in women in western countries. Therefore, we hypothesized that SNPs in ER-α and other estrogen-metabolizing genes contribute to breast cancer risk in Chinese women. In this study, we genotyped polymorphisms in the regulatory regions of ER-α (rs3798577) and other two estrogen-metabolizing enzyme genes CYP17 (rs743572) and CYP19 (rs10046) among 300 breast cancer cases and 390 controls in a Chinese population. Crude and adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression analyses to estimate breast cancer risk associated with these polymorphisms. We found that the T allele frequency of ER-α was significantly higher in cases (59.8%) than controls (54.5%) (P = 0.047), but no significant difference was found in the genotype distribution. However, postmenopausal breast cancer risk was associated with the CYP17 TC genotype (aOR = 1.77, 95% CI = 1.11–2.83) compared with the TT genotype. The CYP19 variant TC + TT genotypes were associated with both overall cancer risk (TT + TC vs. TT aOR = 1.73, 95% CI = 1.13–2.65) and premenopausal cancer risk (TT + TC vs. TT aOR = 1.78, 95% CI = 1.03–3.09), particularly for ER +/PR + tumors. Furthermore, there were joint effects between CYP19 T and ER-α T varint genotypes (aOR = 1.67, 95% CI = 1.03–2.69 for CYP19 TC + TT vs. CC among ER-α T variant carriers) and between CYP19 T and CYP17 C variant genotypes (aOR = 1.77, 95% CI = 1.11–2.83 for CYP19 TC + TT vs. CC among CYP17 variant C carriers). This study provides evidence that polymorphisms CYP17 rs743572, CYP19 rs10046 and ER-α rs3798577 are associated with breast cancer risk among Chinese women.     

Risk of aggressive breast cancer in women of Han nationality carrying TGFB1 rs1982073 C allele and FGFR2 rs1219648 G allele in North China

The high morbidity and aggressive behavior of breast cancer are associated with genetic variations. Single nucleotide polymorphisms (SNPs) in many genes have been demonstrated as a risk factor for breast cancer. In this study, we evaluated the association of the SNP rs1982073 (Leu10Pro) in transforming growth factor-beta 1 (TGFB1) gene and the SNP rs1219648 in fibroblast growth factor receptor 2 (FGFR2) gene with the risk and aggressiveness of breast cancer among women of Han nationality in North China. TaqMan allelic discrimination assay was performed to genotype rs1982073 and rs1219648 in 447 breast cancer cases and 406 age-matched healthy controls. The results imply that genotype frequencies of rs1982073 and rs1219648 were not significantly different between breast cancer patients and healthy controls. However, for TGFB1 SNP rs1982073, the C-carriers (T/C+C/C genotype) were more likely to bear tumors of greater aggressiveness (histological grade III) than T/T-carriers (grade I–II) (OR = 3.45, 95% CI: 1.48–8.00, P = 0.004). For FGFR2 SNP rs1219648, G-carriers (A/G+G/G genotype) were more significantly linked to tumors with lymph node metastasis than those with A/A genotype (lymph node negative) (OR = 1.69, 95% CI: 1.11–2.58, P = 0.016). Therefore, the SNPs of TGFB1 rs1982073 and FGFR2 rs1219648 may contribute to the identification of patients with more aggressive breast cancers among Han women in North China.     

Estrogen receptor genotype is associated with risk of venous thromboembolism during tamoxifen therapy

Thromboembolism is a serious complication of tamoxifen therapy in women with breast cancer. Banked DNA from tamoxifen-treated individuals with breast cancer from the Marshfield Clinic Personalized Medicine Research Project, a population-based DNA repository, was tested for association between incidence of tamoxifen-associated thromboembolic events (TTE) and single nucleotide polymorphisms encoding the estrogen receptors 1,2 (ESR1, ESR2) or drug metabolism enzymes cytochrome P450 2D6 (CYP2D6) and aromatase (CYP19). TTE were experienced by 16/220 subjects with risk association noted for XbaI (rs9340799) genotype and ESR1 Xbal/PvuII diplotype (rs9340799 and rs2234693) (hazard ratio 3.47, 95% CI 0.97–12.44, P = 0.035). Association persisted after adjusting for classical risk factors including age at diagnosis and body mass index at enrollment. Initial evidence of association between increased risk for TTE and ESR1 genotype and ESR1 diplotype is presented. Determination of estrogen receptor genotype may identify a subset of women at increased risk for thromboembolism with tamoxifen exposure.     

Genetic variants in trinucleotide repeat-containing 9 (TNRC9) are associated with risk of estrogen receptor positive breast cancer in a Chinese population

Trinucleotide repeat-containing 9 (TNRC9), a high mobility group chromatin-associated protein, has been implicated in breast cancer metastasis to the bone. Recently, several single nucleotide polymorphisms (SNPs) of TNRC9 were identified as novel breast cancer susceptibility loci by whole genome association studies, especially in estrogen receptor (ER) positive tumors. In the present case–control study of 1,049 breast cancer patients and 1,073 cancer-free controls in a Chinese population, we genotyped three polymorphisms (rs3803662C/T, rs12443621A/G, and rs8051542C/T) of the TNRC9 gene using the SNPstream 12-plex platform to test the hypothesis that these SNPs are associated with breast cancer risk in this population. None of the three polymorphisms was significantly associated with breast cancer risk in the whole data set (P = 0.151, 0.644, and 0.737 for rs3803662, rs12443621. and rs8051542, respectively). However, rs12443621 AG/GG genotypes were significantly associated with increased risk of ER positive breast cancer (OR = 1.38, 95% CI = 1.01–1.88), compared with homozygote AA. In addition, a borderline significantly increased risk was also observed for the variant genotypes (CT/TT) of rs8051542 C/T compared with the wild-type genotype (CC) (adjusted OR = 1.26, 95% CI = 0.99–1.60). Interestingly, a significant interaction was detected between rs12443621A/G and ER status on breast cancer risk in a case-only analysis (P for interaction = 0.004). These findings suggest that genetic variants of TNRC9 may contribute to the development of ER positive breast cancer.     

Differences in breast cancer biological characteristics between ethnic groups in New Zealand

Objective To investigate differences in breast cancer biological characteristics between ethnic groups in Auckland, New Zealand. Design Prospective cohort study. Setting Auckland Breast Cancer Study Group. Participants All people diagnosed with breast cancer in the greater Auckland area between 2000 and 2005 who agreed to participate (1,577). Main outcome measures Size, grade, lymph node status, estrogen receptor (ER), progesterone receptor (PR), lymphovascular invasion (LVI), grade allowing for size, all compared with ethnicity. Results NZ Maori and Pacific Island participants had larger tumours (P < 0.0001), higher grade tumours (P < 0.0001) with more involved lymph nodes (P < 0.0001). When allowing for size, there was still an indication that NZ Maori people had higher grade tumours (P = 0.03). There was no difference in ER, PR and LVI between ethnic groups. Conclusion These data suggest differences in tumour biology related to ethnicity in the Auckland population and this has implications for breast cancer screening and management.     

Genetic variants on chromosome 5p12 are associated with risk of breast cancer in African American women: the Black Women’s Health Study

Two single nucleotide polymorphisms (SNPs), rs4415084, and rs10941679 on chromosome 5p12 were associated with risk of breast cancer in a recent genome-wide association study (GWAS) of women of European ancestry. Both SNPs are located in a large high-LD region and the causal variant(s) are still unknown. We conducted a nested case–control study in a cohort of African American women to replicate and narrow the region carrying the causal variant(s). We evaluated 14 tagging SNPs in a 98 kb LD block surrounding the index SNPs in 886 breast cancer cases and 1,089 controls from the Black Women’s Health Study. We used the Cochran–Armitage trend test to assess association with breast cancer risk. Odds ratios were derived from logistic regression analyses adjusted for potential confounders including percent European admixture. We confirmed the reported association of rs4415084 SNP with overall risk of breast cancer (P = 0.06), and, as in the original study, observed a stronger association with estrogen receptor positive tumors (P = 0.03). We identified four other SNPs (rs6451770, rs12515012, rs13156930, and rs16901937) associated with risk of breast cancer at the nominal alpha value of 0.05; all of them were located in a 59 kb HapMap YRI LD block. After correction for multiple testing, the association with SNP rs16901937 remained significant (P permutated = 0.038). The G allele was associated with a 21% increased risk of breast cancer overall and with a 32% increase in tumors positive for both estrogen and progesterone receptors. The present results from an African ancestry (AA) population confirm the presence of breast cancer susceptibility genetic variants in the chromosome 5p12 region. We successfully used the shorter range of LD in our AA sample to refine the localization of the putative causal variant.     

Cyclin D1 expression is associated with poor prognostic features in estrogen receptor positive breast cancer

Cyclins D1 and E play an important role in breast carcinogenesis. High cyclin E expression is common in hormone receptor negative and high grade aggressive breast cancer, whereas cyclin D1 in hormone receptor positive and low grade breast cancer. Experimental data has suggested that cyclin D1 and E mediate cell proliferation by different mechanisms in estrogen receptor (ER) positive and negative breast cancer. To test this hypotheses in large breast cancer material and to clarify the histopathological correlations of cyclin E and D1, especially the association with proliferation, we analyzed cyclin E and D1 immunohistochemical expression on breast tumour microarrays consisting of 1348 invasive breast cancers. High cyclin D1 expression was associated with high grade (P < 0.0005), high cyclin A (P < 0.0005) and Ki67 (P < 0.0005) expression among ER positive but with low grade (P = 0.05) and low Ki67 (P = 0.01) expression among ER negative breast cancers. Cyclin E and D1 expression correlated positively in ER positive (P < 0.0005) but had a negative correlation in ER negative tumours (P = 0.004). Cyclin E associated with high grade among all tumours (P < 0.0005). In conclusion, the findings of this study show that cyclin D1 has separate roles, and proliferation is driven by different mechanisms in ER positive and negative breast cancers.     

Expression of the forkhead transcription factor FOXP1 is associated with that of estrogen receptorβ in primary invasive breast carcinomas

We previously identified a correlation between estrogen receptor alpha (ERα) and the candidate tumour suppressor gene Forkhead Box P1 (FOXP1), whose nuclear protein expression in breast tumours was associated with improved patient survival. However, the expression pattern of FOXP1 in normal breast tissue is more reminiscent of the second receptor, ERβ, which has an emerging role as a tumour suppressor in breast cancer and critically may underlie the ability of some ERα-negative tumours to respond to tamoxifen. In a series of 283 breast cancers, in which ERα-positive tumours were treated with tamoxifen, the nuclear expression of ERβ correlated significantly with ERα (p = 0.004), low-tumour grade (p = 0.008) and nuclear FOXP1 (p = 0.01). High-grade tumours exhibited significantly more cytoplasmic ERβ than the low-grade tumours (p = 0.006). Regression analysis demonstrated that FOXP1 expression was most closely related to nuclear ERβ (p = 0.021). Neither, nuclear or cytoplasmic ERβ expression demonstrated prognostic significance. FOXP1 is not estrogen regulated and silencing FOXP1 expression, using siRNA, did not affect ERα, ERβ or progesterone receptor expression, suggesting ER and FOXP1 co-expression may reflect a common regulatory mechanism.     

CYP2C19*17 is associated with decreased breast cancer risk

Cytochrome P450 2C19 (CYP2C19) plays an important role in the metabolism of xenobiotics and drugs and contributes to the catabolism of endogenous substrates like estradiol. Genetic variability impacts expression and activity of CYP2C19 and therefore can influence catabolism of estrogens. In the present study we analyzed the association of three polymorphisms of CYP2C19 namely CYP2C19*2 (CYP2C19_681_G>A, rs4244285), CYP2C19*3 (CYP2C19_636_G>A, rs57081121) and CYP2C19*17 (CYP2C19_-806_C>T, rs12248560), with breast cancer susceptibility. We genotyped 1,015 breast cancer cases and 1,021 age-matched, population-based controls of the German GENICA study by matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Risk estimates were calculated by logistic regression. All tests were two-sided. We observed a decreased breast cancer risk for carriers of the CYP2C19*17 allele (OR 0.77, 95% CI: 0.65–0.93; P = 0.005). In subgroup analysis we observed a significant decreased breast cancer risk for women using hormone therapy for ten years or longer who were carriers of the CYP2C19*17 allele (OR 0.57, 95% CI: 0.39–0.83; P = 0.003). Since CYP2C19*17 defines an ultra rapid metabolizer phenotype we suggest that an increased catabolism of estrogens by CYP2C19 may lead to decreased estrogen levels and therefore reduces breast cancer risk. This protective effect seems to be stronger in combination with long-term intake of supplemental estrogens during hormone therapy.     

Variation in the <Emphasis Type="Italic">CYP19A1</Emphasis> gene and risk of colon and rectal cancer

CYP19A1, or aromatase, influences estrogen-metabolizing enzymes and may influence cancer risk. We examine variation in the CYP19A1 gene and risk of colorectal cancer using data from population-based case–control studies (colon n = 1,574 cases, 1,970 controls; rectal n = 791 cases, 999 controls). Four SNPs were statistically significantly associated with colon cancer and four were associated with rectal cancer. After adjustment for multiple comparisons, the AA genotype of rs12591359 was associated with an increased risk of colon cancer (OR 1.44 95% CI 1.16–1.80) and the AA genotype of rs2470144 was associated with a reduced risk of rectal cancer (OR 0.65 95% CI 0.50–0.84). Variants of CYP19A1 were associated with CIMP+ and CIMP+/KRAS2-mutated tumors. CT/TT genotypes of rs1961177 were significantly associated with an increased likelihood of a MSI+ colon tumor (OR 1.77 95% CI 1.26–2.37). We observed statistically significant interactions between genetic variation in NFκB1 and CYP19A1 for both colon and rectal cancer. Our data suggest the importance of CYP19A1 in the development of colon and rectal cancer and that estrogen may influence risk through an inflammation-related mechanism.     

Polymorphisms in DNA repair genes in gastrointestinal stromal tumours: susceptibility and correlation with tumour characteristics and clinical outcome

DNA repair pathways play an essential role in cancer susceptibility by maintaining genomic integrity. This led us to investigate the influence of polymorphisms in the genes coding repair pathway enzymes on gastrointestinal stromal tumours (GIST) susceptibility, tumour characteristics and clinical outcome. We investigated a panel of 20 polymorphisms in 11 genes in 81 cases and 147 controls. The XPD rs13181 wild-type allele and hOGG1 rs1052133 and XPF rs1800067 minor alleles were significantly associated with disease susceptibility. XPA rs1800975 and rs2808668 were associated with tumour size (P = 0.018), metastatic status at onset (P = 0.035) and mitotic index (P = 0.002). With regards to outcome treatment, the XPD rs50872 minor allele had a significant favourable impact on time to progression (TTP). Similarly, the XPC rs2228000 minor allele was correlated with a longer TTP (P = 0.03). On the contrary, the XPC rs2228001 and hOGG1 rs1052133 minor alleles were associated with a diminished TTP (P = 0.005 and P = 0.01, respectively). Regarding OS, we found the presence of at least one hOGG1 (rs1052133) minor allele that had a 60 % lower risk to die compared to the wild-type carriers (P = 0.04). Furthermore, the XRCC3 rs861539 variant allele is associated with a hazard of early death compared with the wild-type genotype (P = 0.04). To the best of our knowledge, this is the first study on polymorphisms in DNA repair genes, belonging to the different pathways, extensively evaluated in GIST patients. Through this multiple candidate gene approach, we report for the first time the significant associations between polymorphisms in DNA repair genes, susceptibility, clinical pathological features and clinical outcome in GIST.

     

Bilateral breast cancer: analysis of incidence,outcome, survival and disease characteristics

There has been conflicting evidence on the impact of bilateral breast cancer (BBC) on the survival and management of patients. The objectives of this study were to address the incidence of BBC and to investigate its characteristics and outcome compared to unilateral cancer. Data were acquired from the prospectively maintained NUIG breast cancer database between 1988 and 2008. BBC were then categorized as synchronous (within 12 months) or metachronous (after 12 months of first tumour). SPSS was used for data analysis. The incidence of BBC in our population was 4.4% (112 of 2,524). Of those 2.1% were synchronous while 2.3% were metachronous. Compared to unilateral cases, bilateral cancer patients were younger (P = 0.021) and had smaller size (P = 0.001) and earlier stage (P < 0.001) tumours at diagnosis. We identified the HER2/neu positivity as a risk factor for developing contralateral breast tumour and ER negativity as a risk factor for developing metachronous tumours. While there was no significant difference in survival for patients with bilateral compared to unilateral tumour (P > 0.05), the synchronous tumour was associated with poorer survival (P = 0.010) in comparison to metachronous tumour. This large single-institutional experience does not support the increasing practice of prophylactic mastectomy but does justify regular follow-up with mammography for early detection of contralateral tumour.     

CYP19A1基因多态性与晚期乳腺癌阿那曲唑治疗疗效相关性研究

[目的]研究CYP1 9A 1基因的rs4646和rs 10046位点多态性与晚期乳腺癌阿那曲唑治疗疗效的相关性.[方法]本研究共纳入272例激素受体阳性晚期乳腺癌患者,接受阿那曲唑治疗后抽取患者外周静脉血,提取DNA,多重PCR获取目的基因片段后,采用直接测序法分析CYP19A1基因多态性.对比等位基因分布频率在突变型和野生型两组患者中的差异.[结果]被检测的rs4646和rs 10046符合Hardy-Weinberg平衡检验;比较rs4646突变型和野生型两组阿那曲唑疗效,32例完全缓解的患者中24例是rs4646突变型,76例疾病进展者中有60例是rs4646野生型,P＜0.005,经过Bonferroni矫正P值仍有统计学意义.与rS4646野生型相比,携带rs4646突变型患者的中位生存期(median survival time,MST)显著延长(Log-rank检验P=0.007).携带rs4646突变型患者的疾病进展时间(time to progression,TTP)显著延长(Log-rank检验P=0.049).[结论]rs4646多态性位点可能会成为预测晚期乳腺癌阿那曲唑治疗疗效和预后的预测因子.     

Variation in genes required for normal mitosis and risk of breast cancer

The down-regulation of genes involved in normal cell division can cause aberrant mitoses and increased cell death. Surviving cells exhibit aneuploidy and/or polyploidy. Since mitotic disruption has been linked with tumor development and progression, alterations in the expression or activity of these mitotic regulators may contribute to breast tumor formation. We evaluated associations between common inherited variation in these genes and breast cancer risk. Two hundred and five tagging and candidate functional single nucleotide polymorphisms in 30 genes required for normal cell division were genotyped in 798 breast cancer cases and 843 controls from the Mayo Clinic breast cancer study. Two variants in EIF3A (rs10787899 and rs3824830; P < 0.01) and four variants in SART1 (rs660118, rs679581, rs754532, and rs735942; P _trend ≤ 0.02) were significantly associated with an altered risk of breast cancer along with single variants in RRM2, PSCD3, C11orf51, CDC16, SNW1, MFAP1, and CDC2 (P < 0.05). Variation in both SART1 (P = 0.009) and EIF3A (P = 0.02) was also significant at the gene level. Analyses suggested that SART1 SNPs rs660118 and rs679581 accounted for the majority of the association of that gene with breast cancer. The observed associations between breast cancer risk and genetic variation in the SART1 and EIF3A genes that are required for maintenance of normal mitosis suggest a direct role for these genes in the development of breast cancer.     

The influence of overweight and insulin resistance on breast cancer risk and tumour stage at diagnosis: a prospective study

It is hypothesized that insulin resistance and related metabolic factors may influence breast cancer risk, however the epidemiological evidence remains inconclusive. We conducted a case–control study nested in a prospective cohort in Northern Sweden, to clarify the associations of body mass index (BMI), leptin, adiponectin, C-peptide, and glycated haemoglobin (HbA1c) with breast cancer risk. We also investigated whether these associations may be modified by age at diagnosis, tumour stage, and oestrogen and progesterone receptor status. During follow-up, 561 women developed invasive breast cancer and 561 matched controls were selected. Conditional logistic regression was used to calculate odds ratios (OR) as estimates of relative risk, and 95% confidence intervals (CI). The associations of BMI, leptin and HbA1c with breast cancer risk differed significantly according to whether the tumour was diagnosed as stage I or stage II–IV (P _{heterogeneity} all <0.05). These factors were significantly inversely associated with risk in the group of stage I tumours, with ORs for top vs. bottom tertile for BMI of 0.48 (95% CI, 0.30–0.78, P _trend = 0.004); leptin, 0.64 (95% CI, 0.41–1.00, P _trend = 0.06); and HbA1c, 0.47 (95% CI, 0.28–0.80, P _trend = 0.005). For stage II–IV tumours, there was a suggestion of an increased risk with higher levels of these factors. There were no significant differences in the associations of BMI, leptin, adiponectin, C-peptide and HbA1c with breast cancer risk in subgroups of age at diagnosis or tumour receptor status. This prospective study suggests that BMI, leptin and HbA1c influence breast tumour initiation and progression. Anne E. Cust and Tanja Stocks contributed equally to this work.     

Melatonin pathway genes and breast cancer risk among Chinese women

Previous studies suggest that melatonin may act on cancer growth through a variety of mechanisms, most notably by direct anti-proliferative effects on breast cancer cells and via interactions with the estrogen pathway. Three genes are largely responsible for mediating the downstream effects of melatonin: melatonin receptors 1a and 1b (MTNR1a and MTNR1b), and arylalkylamine N-acetyltransferase (AANAT). It is hypothesized that genetic variation in these genes may lead to altered protein production or function. To address this question, we conducted a comprehensive evaluation of the association between common single nucleotide polymorphisms (SNPs) in the MTNR1a, MTNR1b, and AANAT genes and breast cancer risk among 2,073 cases and 2,083 controls, using a two-stage analysis of genome-wide association data among women of the Shanghai Breast Cancer Study. Results demonstrate two SNPs were consistently associated with breast cancer risk across both study stages. Compared with MTNR1b rs10765576 major allele carriers (GG or GA), a decreased risk of breast cancer was associated with the AA genotype (OR = 0.78, 95% CI = 0.62–0.97, P = 0.0281). Although no overall association was seen in the combined analysis, the effect of MTNR1a rs7665392 was found to vary by menopausal status (P-value for interaction = 0.001). Premenopausal women with the GG genotype were at increased risk for breast cancer compared with major allele carriers (TT or TG) (OR = 1.57, 95% CI = 1.07–2.31, P = 0.020), while postmenopausal women were at decreased risk (OR = 0.58, 95% 0.36–0.95, P = 0.030). No significant breast cancer associations were found for variants in the AANAT gene. These results suggest that common genetic variation in the MTNR1a and 1b genes may contribute to breast cancer susceptibility, and that associations may vary by menopausal status. Given that multiple variants in high linkage disequilibrium with MTNR1b rs76653292 have been associated with altered function or expression of insulin and glucose family members, further research may focus on clarifying this relationship.     

Three polymorphisms in interleukin-1β gene and risk for breast cancer: a meta-analysis

Interleukin-1β (IL-1β), which is involved in inflammatory and immunological responses, plays an important role in the development and progression of breast cancer. Three functional single nucleotide polymorphisms (SNPs) identified in IL-1β gene are thought to influence breast cancer risk. The results of the association between IL-1β polymorphisms and breast cancer remain inconsistent. Therefore, we conducted a meta-analysis of eight case–control studies with rs1143627 (T > C), rs16944 (C > T), and rs1143634 (C > T). We found that the variant CC genotype of rs1143627 was associated with a significantly increased breast cancer risk (CC vs. TT: OR = 1.37, 95% CI = 1.10–1.70, P = 0.22 for heterogeneity; the recessive model CC vs. TT/TC: OR = 1.40, 95% CI = 1.17–1.67, P = 0.49 for heterogeneity). For rs16944 (C > T) and rs1143634 (C > T), no significant associations were found in all genetic models. In conclusion, the present meta-analysis suggests that rs1143627 is associated with breast cancer risk.     

MIB1/Ki-67 labelling index can classify grade 2 breast cancer into two clinically distinct subgroups

Histological grade is recognized as one of the strongest prognostic factors in operable breast cancer (BC). Although grade 1 and grade 3 tumours are biologically and clinically distinct, grade 2 tumours bear considerable difficulty in outcome prediction and planning therapies. Several attempts such as genomic grade index have been performed to subclassify grade 2 into two subgroups with clinical relevance. Here, we present evidence that the routinely evaluable immunohistochemical MIB1/Ki67 labelling index (MIB-LI) can classify grade 2 tumours into two clinically distinct subgroups. In this study, growth fractions of 1,550 primary operable invasive breast carcinomas were immunohistochemically assayed on full-face tissue sections using the MIB1 clone of Ki-67. Growth fractions were assessed as number of MIB1 positive nuclei in 1,000 tumour nuclei at high-power magnification and expressed as MIB1-LI. Using a 10% cut-point of MIB1-LI, grade 2 BCs were classified into low (49.8%) and high (50.2%) proliferative subgroups. Univariate and multivariate survival analysis revealed statistically significant differences between these subgroups regarding patients’ BC specific survival (P < 0.001), and metastasis free survival (P < 0.001) which was independent of the well-established prognostic factors (HR = 2.944, 95% CI = 1.634–5.303, P < 0.001). In conclusion, our results further demonstrate that grade 2 BCs may represent at least two biological or behaviourally different entities. Assay of growth fraction in BC using MIB1/Ki67 immunohistochemistry is a robust cost-effective diagnostic tool that subdivides grade 2 tumours into low and high risk populations providing additional prognostic information in planning therapies and outcome prediction.