Associação entre o polimorfismo do gene metalopeptidase de matriz 9 e o risco de câncer de mama

rbgo Revista Brasileira de Ginecologia e Obstetrícia Rev. Bras. Ginecol. Obstet. 0100-7203 1806-9339 Federação Brasileira das Sociedades de Ginecologia e Obstetrícia Resumo Objetivo Estudos epidemiológicos vêm demonstrando evidências da influência de variações genéticas na patogênese do câncer de mama, e têm sugerido associação de polimorfismos comuma maior susceptibilidade à doença. A metalopeptidase dematriz 9 (MMP-9) é uma colagenase responsável pela degradação do colágeno tipo IV, omaior componente da membrana basal, e outros componentes essenciais da matriz extra celular, estando envolvido na invasão da célula tumoral emetástase. Nosso objetivo foi avaliar a associação entre o polimorfismo da 1562 C/T (rs 3918242) do gene MMP-9 e o desenvolvimento da neoplasia mamária. Métodos Neste estudo caso-controle, a frequência de polimorfismo 1562 C/T (rs 3918242) do MMP-9 foi determinada em 148 mulheres com câncer de mama e 245 mulheres sem a doença. O DNA foi extraído do plasma e o gene foi amplificado por meio de reação em cadeia da polimerase (RCP). O polimorfismo foi determinado por enzimas de restrição. Resultados O polimorfismo, após o ajuste para variáveis confundidoras, não foi associado coma ocorrência de câncer de mama (razão de possibilidade [RP] = 1,159, intervalo de confiança de 95% [IC95]: 0,6625-1,997, p = 0,5964). Também não foi demonstrado associação comestadiamentos mais avançados, presença de receptores hormonais, superexpressão de HER2 e tampouco com a taxa de proliferação celular do tumor. Conclusão Não observamos relação entre o polimorfismo 1562 C/T (rs 3918242) do gene MMP-9 e a ocorrência de câncer de mama. Introduction Breast cancer is the most common type of cancer in the female population when disregarding cases of non-melanoma skin cancer. The mortality rate due to the disease presents an upward curve,1 contributing to make breast cancer a major public health problem and an important cause of mortality in adults.2 In 2018, 59,700 new cases were estimated in Brazil, representing an incidence rate of more than 56 cases per 100,000 women.1 Approximately 10 to 15% of breast cancer patients have a previous family history of the disease; however, only 5% can be explained by mutation of genes such as BRCA1 and BRCA2.3 Regarding family risk for the development of the disease, it is necessary to consider the influence of environmental factors and genetic variations that may alter the predisposition to the risk of breast cancer.4 Metalloproteinases (MMPs) are a family of endopeptidases participating in the degradation of extra cellular matrix and basement membrane barriers.5 6 7 Some members of the MMPs family have been shown to promote tumor growth, angiogenesis, invasion and metastasis in cancer patients.8 9 10 Matrix metallopeptidase 9 (MMP-9) is a collagenase responsible for the degradation of type IV collagen, the major component of the basement membrane, and others essential extra cellular matrix component̀s, being involved in the tumor cell invasion and metastasis.11 12 The gene MMP-9 is located on chromosome region 20q11.2-q13.1.13 Genetic variation may alter MMP-9 expression, influencing breast cancer susceptibility.14 Differential expression of MMP-9 reflects the degree of differentiation of breast cancer cells and that its overexpression is closely related with the most aggressive subtypes.15 Several single-nucleotide polymorphisms (SNPs) have been reported to be correlated with tumor progression and worse disease prognosis. Among MMP-9 polymorphisms, 1562 C/T (rs 3918242), a C to T substitution at −1562 bp, is the most studied.14 Researches have been performed to confirm the relationship between the pointed polymorphism and breast cancer susceptibility, however results are inconclusive.14 In this clinical, cross-sectional case-control study, we evaluated the potential relationship of the MMP-9 gene polymorphism with breast cancer and aggressiveness of the disease. Methods We studied 393 women, recruited between 2013 and 2015, who were followed up in the mastology sector of the division of gynecology of the Faculdade de Medicina do ABC (FMABC). The participants were divided into two groups: 148 with histologically confirmed diagnosis of breast cancer (case group) and 245 without the disease, with normal clinical and mammographic examinations (control group). For the patients with breast cancer, staging of the disease was retrieved from the patients' records, based on the tumor, node and metastasis (TNM) classification of malignant tumors. Immunohistochemical analysis of the tumor was performed to determine the presence of estrogen receptors (detected using the EP1 clone), human epidermal growth factor receptor 2 (HER2) overexpression and Ki67. Tumors exhibiting at least 1% of tumor cells staining for estrogen receptor were considered positive. Breast cancers were tested for HER2 overexpression by immunohistochemistry (IHC), and cases showing equivocal (2 + ) staining by IHC required reflex testing by HHER2 D-FISH. The Ki67 cut-off was considered 25%. Clinical data were collected with the use of a questionnaire; the following data were recorded: age, age at menarche and last menstruation, number of pregnancies, previous use of hormonal medications, breastfeeding, history of smoking, alcohol consumption and endocrine diseases. The patients included were informed about the study and signed a consent form. Venous blood samples were collected from women of both groups, and genomic DNA was extracted using the Illustra blood genomic prep mini spin reagent kit (GE Healthcare, Chicago, IL, USA), following the manufacturer's instructions. The presence of the MMP-9 polymorphism was determined following the PCR-RFLP procedure described by Zhang et al (1999).16 For the amplification of the promoter region of the gene by polymerase chain reaction (PCR), the following primers were used: 5′-GCC TGG CAC ATA GTA GGC CC-3′ e 5′- CTT CCT AGC CAG CCG GCA TC -3′. The 435-bp PCR products were treated with the Sphl restriction enzyme, and the restriction fragments were separated by electrophoresis in 2.5% agarose stained with ethidium bromide. At the end of the analysis, C/C homozygotes should present a single 435-bp band, T/T homozygotes should present two bands of 247 and 188 bp, and T/C heterozygotes should present three bands of 435, 247 and 188 bp. To assess the association between the study groups and the categorical variables, we used the frequency chi-squared test, whereas the continuous variables were analyzed using the unpaired t-test. The Hardy-Weinberg equilibrium was also tested using the chi-squared test. After the stratification of the groups, the effect of the MMP-9 polymorphism on breast cancer development was estimated by the odds ratio (OR), obtained by the binary logistic regression model, using the SPSS software, version 23.0 (IBM Corp., Armonk, NY, USA). The confidence interval adopted was 95% (95%CI), and the value for rejection of the null hypothesis was set at 0.05 or 5% (α ≤ 0.05). The project was approved by the Research Ethics Committee of the institution under number 169/2010. Results A total of 148 women were included in the case group, and 245 women were included in the control group. The clinical and epidemiological characteristics of both groups are described in Table 1. Both groups presented homogeneity for almost all of the characteristics evaluated, with similar proportions of women over 50 years of age, menopausal women and/or women who used hormone therapy in the case and control groups. The variable parity and the age at first pregnancy also showed no significant differences between the groups. Cases were more likely to use oral contraceptives than controls, with frequency of use at 22.3% and 6.1%, respectively (p< 0.0001). The family history of breast cancer (p= 0.04) was more frequent in women who presented with the disease, with a difference of almost 10% between the groups. Table 1 Matrix metallopeptidase 9 polymorphism—clinical characteristics of cases and controls Characteristics Cases (n= 148) Controls (n= 245) p-value Age (years)# 57.8 ± 0.9 59.5 ± 0.6 0.134 Age at menarche (years)# 12.9 ± 0.1 13.2 ± 0.1 0.059 Postmenopause* 121 (81.7%) 82. 7% 0.785 Parity* 2.6 ± 0.12 2.9 ± 0.09 0.067 Breastfeeding* 116 (78.4%) 207 (84.5%) 0.13 Age at first pregnancy# 23.1 ± 0.45 22.7 ± 0.3 0.54 Use of oral contraceptive* 33 (22.3%) 15 (6.1%) < 0.0001** Use of hormone therapy* 13 (8.7%) 36 (14.7%) 0.114 Family history of breast cancer* 25 (16.9%) 18 (7.3%) 0.004** Continuous variables: values expressed as the mean and standard deviation; Categorical variables: values expressed as numbers and percentages; # Unpaired t-test; * Chi-squared test; ** Significant values Genotyping and frequency of the alleles are described in Table 2. The distribution of the genotypes is in genetic equilibrium according to the Hardy-Weinberg principle in the case and control groups. Table 2 Matrix metallopeptidase 9 polymorphism and the occurrence of breast cancer CC TC + TT OR crude (CI) OR adjusted (CI)* Cases 115 (82.7%) 24 (17.3%) 1.159 (0.6625–1.997)p= 0.5964 Controls 186 (80.5%) 45 (19.5%) Abbreviations: CI, confidence interval; OR, odds ratio. Due to the low incidence of the TT genotype in the studied population, we chose to analyze the results comparing the wild homozygous group (CC) with the polymorphic group (TC + TT). After adjusting for oral contraceptive use and family history of breast cancer, the presence of the T allele and the TT (TC + TT) genotype of the MMP-9 polymorphism was not directly associated with tumor occurrence (OR = 1.159, 95%CI: 0.6625–1.997, p= 0.5964). In addition, no statistically significant difference was found between the polymorphisms when analyzing according to the staging of the disease, estrogen receptor status, HER2 overexpression or non-overexpression, or cell proliferation rate represented by Ki67, as shown in Table 3. Table 3 Evaluation of matrix metallopeptidase 9 polymorphism and staging, status of estrogen receptor, HER2 and Ki67 CC TC + TT p-value* Staging IA–IIBStaging IIB–IV 90 (81%)25 (89%) 21 (19%)3 (11%) 0.4075 Estrogen receptor+ 86 (81.9%) 19 (18.1%) 0.796 Estrogen receptor - 29 (85.3%) 5 (14.7%) HER2 + 21 (87.5%) 3 (12.5%) 0.766 HER2 - 94 (81.7%) 21 (18.3%) Ki67 ≤ 25% 58 (85.3%) 10 (14.7%) 0.244 Ki67 > 25% 41 (75.9%) 13 (24.1%) Abbreviation: HER2, human epidermal growth factor receptor 2. Chi-squared test Discussion Hereditary predisposition to breast cancer significantly influences the screening and follow-up of women at high risk for developing the disease, enabling early diagnosis, personalized conduct and family counseling. However, in patients with a personal or family history of breast cancer, a specific genetic predisposition is identified in less than 30% of cases.17 Thus, it seems that the effect of low-penetrance gene polymorphisms on the risk for breast cancer is relevant only in polygenic forms.17 Studies have demonstrated that degradation of extra cellular matrix and basement membrane by MMPs play an important role in tumorigenesis by modulating cell proliferation, apoptosis, tumor invasion and metastasis.18 The role played by MMP-9 in the malignancy and the growth of the tumor is an important one.14 Numerous single-nucleotide polymorphisms (SNPs) have already been identified in the MMP-9 gene, and the most common variant is 1562 C/T (rs 3918242). Our study demonstrated that the T allele and the TT genotype of the MMP-9 polymorphism were not directly associated with the occurrence of breast cancer, as shown in Table 2. The association between this polymorphism and the disease has already been studied by groups from several countries, without a direct relationship being established. An Indian study revealed that the frequency of T-allele of MMP-9–1562 C/T promoter polymorphism was found to be predominant in breast cancer group compared with controls, with a 1.44 folds increased risk for breast cancer.19 Merdad et al20 showed that MMP-9 is a reliable potential candidate diagnostic biomarker and drug target in breast cancer. An Iranian study,18 published in 2015, found association between higher risk of developing breast cancer and MMP-9 polymorphism, as the presence of mutant allele increased the susceptibility to the disease by 1.87 times (OR = 1.87, IC95: 1.05–3.33, p= 0.035). Similarly, a large meta-analysis,7 also from 2015, showed an association between TT genotype of MMP-9–1562 C/T polymorphism and a higher risk for breast cancer. This result was in contrast to our study, which was supported by a South Brazilian research (p= 0.23)21 and a meta-analysis conducted by Zhou et al,22 which involved more than 5,000 patients. Both studies found no evidence that the 1562 C/T polymorphism (rs3918242) is correlated with a higher risk for breast cancer. Several studies have described the role of MMPs in breast cancer progression and metastasis development, as MMPs are involved in the degradation of basement membranes.23 In a meta-analysis24 including more than 10,000 cancer cases, MMP-9 (1562 C/T) was shown to increase the risk of cancer metastasis, correlating the polymorphism with a more aggressive disease (OR = 1.25, IC95: 1.03 - 1.51, p= 0.07). Our results were inconsistent with this finding, as the adjustment for disease stage did not involve a higher frequency of polymorphism in more advanced tumors (p= 0.4075). A factor with strong involvement that has not yet been established as a risk factor is the use of oral contraceptive, which, in our study, was related to higher occurrence of the disease (p< 0.0001).25 A meta-analysis26 correlating Iranian studies demonstrated that the use of oral contraceptives may stimulate the occurrence of breast cancer because it directly increases estrogen levels and indirectly influences weight gain. Our finding is consistent with the results reported in an analysis27 published in 2016, which showed an OR of breast cancer development that was 54.6% lower in patients who did not use oral contraceptives compared with those who used it. Approximately 5 to 10% of breast cancer cases are familial and occur earlier than those in the general population. The BRCA1 and BRCA2 mutations are primarily responsible for hereditary breast cancer.28 Despite years of research, it has been shown that a minority of patients with a personal or family history of breast cancer have a genetic mutation as an identifiable cause.17 Our study is consistent with the global literature, as we found a positive association of family history with development of the disease (p= 0.004). Stratified analysis according to HER2 or estrogen receptor expression in neoplastic cells showed no relationship with the occurrence of the polymorphism studied, and similarly, Ki67—a tumor cell proliferation index—was not a factor associated with the greater presence of the polymorphic alleles. We believe, however, that more studies are needed to confirm any of the proposed hypotheses due to the lack of evidence in the literature on the subject. Conclusion The main results of this study suggest that the T allele and the TT genotype of 1562 C/T (rs 3918242) of the MMP-9 do not play a key role in breast cancer development. Although research has been performed to explore the role of SNPs of this gene in breast cancer, the results are inconclusive. We note that the controversy remains over the influence of 1562 C/T (rs 3918242) of the MMP-9 on the genesis of breast cancer. More studies and a larger case sample are necessary to confirm the effects on the risk of breast cancer to assist in the screening and follow-up of patients at increased risk of the disease. Acknowledgments The authors would like to thank the patients for their contribution to the research, the anesthesiologist team of the services where the project was developed for the aid in collecting the material, and the interns of the Department of Biochemistry of FMABC for their dedication to the analysis of the material obtained. References 1 1 Ministério da Saúde. Instituto Nacional de Câncer José Alencar Gomes da Silva. Estimativa 2018: Incidência de Câncer no Brasil. Rio de Janeiro, RJ: INCA; 2017. http://www.inca.gov.br/estimativa/ 2018/estimativa-2018.pdf. Accessed December 17, 2017 Ministério da Saúde Instituto Nacional de Câncer José Alencar Gomes da Silva. Estimativa 2018: Incidência de Câncer no Brasil. Rio de Janeiro, 2017 RJ INCA 2 2 Zhou LP, Yao F, Luan H, et al. CYP3A4 1B polymorphismand cancer risk: a HuGE review and meta-analysis. Tumour Biol 2013;34(02): 649-660. Doi: 10.1007/s13277-012-0592-z Zhou LP Yao F Luan H CYP3A4 1B polymorphismand cancer risk a HuGE review and meta-analysis Tumour Biol 2013 34 02 649 660 10.1007/s13277-012-0592-z 3 3 Newman B, Austin MA, Lee M, King MC. Inheritance of human breast cancer: evidence for autosomal dominant transmission in high-risk families. Proc Natl Acad Sci U S A 1988;85(09):3044- -3048. Doi: 10.1073/pnas.85.9.3044 Newman B Austin MA Lee M King MC Inheritance of human breast cancer evidence for autosomal dominant transmission in high-risk families Proc Natl Acad Sci U S A 1988 85 09 3044 3044 10.1073/pnas.85.9.3044 4 4 Dunning AM, Healey CS, Pharoah PDP, TeareMD, Ponder BAJ, Easton DF.Asystematic reviewofgeneticpolymorphisms andbreast cancer risk. Cancer Epidemiol Biomarkers Prev 1999;8(10):843-854 Dunning AM Healey CS Pharoah PDP Teare MD Ponder BAJ Easton DF Asystematic reviewofgeneticpolymorphisms andbreast cancer risk Cancer Epidemiol Biomarkers Prev 1999 8 10 843 854 5 5 Belkin AM, Akimov SS, Zaritskaya LS, Ratnikov BI, Deryugina EI, Strongin AY. Matrix-dependent proteolysis of surface transglutaminase by membrane-type metalloproteinase regulates cancer cell adhesion and locomotion. J Biol Chem 2001;276(21): 18415-18422. Doi: 10.1074/jbc.M010135200 Belkin AM Akimov SS Zaritskaya LS Ratnikov BI Deryugina EI Strongin AY Matrix-dependent proteolysis of surface transglutaminase by membrane-type metalloproteinase regulates cancer cell adhesion and locomotion J Biol Chem 2001 276 21 18415 18422 10.1074/jbc.M010135200 6 6 Przybylowska K, Kluczna A, Zadrozny M, et al. Polymorphisms of the promoter regions of matrix metalloproteinases genesMMP-1 and MMP-9 in breast cancer. Breast Cancer Res Treat 2006;95(01): 65-72. Doi: 10.1007/s10549-005-9042-6 Przybylowska K Kluczna A Zadrozny M Polymorphisms of the promoter regions of matrix metalloproteinases genesMMP-1 and MMP-9 in breast cancer Breast Cancer Res Treat 2006 95 01 65 72 10.1007/s10549-005-9042-6 7 7 Savinov AY, Remacle AG, Golubkov VS, et al. Matrix metalloproteinase 26 proteolysis of the NH2-terminal domain of the estrogen receptor beta correlateswith the survival of breast cancer patients. Cancer Res 2006;66(05):2716-2724 Savinov AY Remacle AG Golubkov VS Matrix metalloproteinase 26 proteolysis of the NH2-terminal domain of the estrogen receptor beta correlateswith the survival of breast cancer patients Cancer Res 2006 66 05 2716 2724 8 8 Egeblad M, Werb Z. New functions for the matrix metalloproteinases in cancer progression. Nat Rev Cancer 2002;2(03):161-174. Doi: 10.1038/nrc745 Egeblad M Werb Z New functions for the matrix metalloproteinases in cancer progression Nat Rev Cancer 2002 2 03 161 174 10.1038/nrc745 9 9 Folgueras AR, Pendás AM, Sánchez LM, López-Otín C. Matrix metalloproteinases in cancer: from new functions to improved inhibition strategies. Int J Dev Biol 2004;48(5-6):411-424. Doi: 10.1387/ijdb.041811af Folgueras AR Pendás AM Sánchez LM López-Otín C Matrix metalloproteinases in cancer from new functions to improved inhibition strategies Int J Dev Biol 2004 48 5-6 411 424 10.1387/ijdb.041811af 10 10 Lemaître V, D'Armiento J. Matrix metalloproteinases in development and disease. Birth Defects Res C EmbryoToday 2006;78(01): 1-10. Doi: 10.1002/bdrc.20065 Lemaître V D'Armiento J Matrix metalloproteinases in development and disease Birth Defects Res C EmbryoToday 2006 78 01 1 10 10.1002/bdrc.20065 11 11 Liotta LA, Tryggvason K, Garbisa S, Hart I, Foltz CM, Shafie S. Metastatic potential correlates with enzymatic degradation of basement membrane collagen. Nature 1980;284(5751):67-68 Liotta LA Tryggvason K Garbisa S Hart I Foltz CM Shafie S Metastatic potential correlates with enzymatic degradation of basement membrane collagen Nature 1980 284 5751 67 68 12 12 Duffy MJ, Maguire TM, Hill A, McDermott E, O'Higgins N. Metalloproteinases: role in breast carcinogenesis, invasion and metastasis. Breast Cancer Res 2000;2(04):252-257 Duffy MJ Maguire TM Hill A McDermott E O'Higgins N Metalloproteinases role in breast carcinogenesis, invasion and metastasis Breast Cancer Res 2000 2 04 252 257 13 13 St Jean PL, Zhang XC, Hart BK, et al. Characterization of a dinucleotide repeat in the 92 kDa type IV collagenase gene (CLG4B), localization of CLG4B to chromosome 20 and the role of CLG4B in aortic aneurysmal disease. Ann Hum Genet 1995;59 (Pt 1):17-24. Doi: 10.1111/j.1469-1809.1995.tb01602.x St Jean PL Zhang XC Hart BK Characterization of a dinucleotide repeat in the 92 kDa type IV collagenase gene (CLG4B), localization of CLG4B to chromosome 20 and the role of CLG4B in aortic aneurysmal disease Ann Hum Genet 1995 59 1 17 24 10.1111/j.1469-1809.1995.tb01602.x 14 14 Zhang X, Jin G, Li J, Zhang L. Association between four MMP-9 polymorphisms and breast cancer risk: a meta-analysis. Med Sci Monit 2015;21:1115-1123. Doi: 10.12659/MSM.893890 Zhang X Jin G Li J Zhang L Association between four MMP-9 polymorphisms and breast cancer risk a meta-analysis Med Sci Monit 2015 21 1115 1123 10.12659/MSM.893890 15 15 Yousef EM, Tahir MR, St-Pierre Y, Gaboury LA. MMP-9 expression varies according to molecular subtypes of breast cancer. BMC Cancer 2014;14:609. Doi: 10.1186/1471-2407-14-609 Yousef EM Tahir MR St-Pierre Y Gaboury LA MMP-9 expression varies according to molecular subtypes of breast cancer BMC Cancer 2014 14 609 609 10.1186/1471-2407-14-609 16 16 Zhang B, Ye S, Herrmann SM, et al. Functional polymorphism in the regulatory region of gelatinase B gene in relation to severity of coronary atherosclerosis. Circulation 1999;99(14):1788-1794. Doi: 10.1161/01.CIR.99.14.1788 Zhang B Ye S Herrmann SM Functional polymorphism in the regulatory region of gelatinase B gene in relation to severity of coronary atherosclerosis Circulation 1999 99 14 1788 1794 10.1161/01.CIR.99.14.1788 17 17 Shiovitz S, Korde LA. Genetics of breast cancer: a topic in evolution. Ann Oncol 2015;26(07):1291-1299. Doi: 10.1093/annonc/ mdv022 Shiovitz S Korde LA Genetics of breast cancer a topic in evolution Ann Oncol 2015 26 07 1291 1299 10.1093/annonc/ 18 18 Rahimi Z, Yari K, Rahimi Z. Matrix metalloproteinase-9 -1562T allele and its combinationwithMMP-2 -735 C allele are risk factors for breast cancer. Asian Pac J Cancer Prev 2015;16(03):1175-1179 Rahimi Z Yari K Rahimi Z Matrix metalloproteinase-9 -1562T allele and its combinationwithMMP-2 -735 C allele are risk factors for breast cancer Asian Pac J Cancer Prev 2015 16 03 1175 1179 19 19 Padala C, Tupurani MA, Puranam K, et al. Synergistic effect of collagenase-1 (MMP1), stromelysin-1 (MMP3) and gelatinase-B (MMP9) gene polymorphisms in breast cancer. PLoS One 2017;12 (09):e0184448. Doi: 10.1371/journal.pone.0184448 Padala C Tupurani MA Puranam K Synergistic effect of collagenase-1 (MMP1), stromelysin-1 (MMP3) and gelatinase-B (MMP9) gene polymorphisms in breast cancer PLoS One 2017 12 09 e0184448 10.1371/journal.pone.0184448 20 20 Merdad A, Karim S, Schulten HJ, et al. Expression of matrix metalloproteinases (MMPs) in primary human breast cancer: MMP-9 as a potential biomarker for cancer invasion and metastasis. Anticancer Res 2014;34(03):1355-1366 Merdad A Karim S Schulten HJ Expression of matrix metalloproteinases (MMPs) in primary human breast cancer MMP-9 as a potential biomarker for cancer invasion and metastasis Anticancer Res 2014 34 03 1355 1366 21 21 Roehe AV, Frazzon AP, Agnes G, Damin AP, Hartman AA, Graudenz MS. Detection of polymorphisms in the promoters of matrix metalloproteinases 2 and 9 genes in breast cancer in South Brazil: preliminary results. Breast Cancer Res Treat 2007;102(01): 123-124. Doi: 10.1007/s10549-006-9273-1 Roehe AV Frazzon AP Agnes G Damin AP Hartman AA Graudenz MS Detection of polymorphisms in the promoters of matrix metalloproteinases 2 and 9 genes in breast cancer in South Brazil preliminary results Breast Cancer Res Treat 2007 102 01 123 124 10.1007/s10549-006-9273-1 22 22 Zhou P, Du LF, Lv GQ, et al. Current evidence on the relationship between four polymorphisms in the matrix metalloproteinases (MMP) gene and breast cancer risk: a meta-analysis. Breast Cancer Res Treat 2011;127(03):813-818. Doi: 10.1007/s10549- 010-1294-0 Zhou P Du LF Lv GQ Current evidence on the relationship between four polymorphisms in the matrix metalloproteinases (MMP) gene and breast cancer risk a meta-analysis Breast Cancer Res Treat 2011 127 03 813 818 23 23 Jones JL,Walker RA. Control of matrix metalloproteinase activity in cancer. J Pathol 1997;183(04):377-379. Doi: 10.1002/(SICI) 1096-9896(199712)183:4<377:AID-PATH951>3.0.CO;2-R Jones JL Walker RA Control of matrix metalloproteinase activity in cancer J Pathol 1997 183 04 377 379 24 24 Liu D, Guo H, Li Y, Xu X, Yang K, Bai Y. Association between polymorphisms in the promoter regions of matrix metalloproteinases (MMPs) and risk of cancer metastasis: a meta-analysis. PLoS One 2012;7(02):e31251. Doi: 10.1371/journal.pone.0031251 Liu D Guo H Li Y Xu X Yang K Bai Y Association between polymorphisms in the promoter regions of matrix metalloproteinases (MMPs) and risk of cancer metastasis a meta-analysis PLoS One 2012 7 02 e31251 10.1371/journal.pone.0031251 25 25 Key TJ, Verkasalo PK, Banks E. Epidemiology of breast cancer. Lancet Oncol 2001;2(03):133-140. Doi: 10.1016/S1470-2045(00) 00254-0 Key TJ Verkasalo PK Banks E Epidemiology of breast cancer Lancet Oncol 2001 2 03 133 140 26 26 Soroush A, Farshchian N, Komasi S, Izadi N, Amirifard N, Shahmohammadi A. The role of oral contraceptive pills on increased risk of breast cancer in Iranian populations: a meta-analysis. J Cancer Prev 2016;21(04):294-301. Doi: 10.15430/JCP.2016.21.4.294 Soroush A Farshchian N Komasi S Izadi N Amirifard N Shahmohammadi A The role of oral contraceptive pills on increased risk of breast cancer in Iranian populations a meta-analysis J Cancer Prev 2016 21 04 294 301 10.15430/JCP.2016.21.4.294 27 27 Cauchi JP, Camilleri L, Scerri C. Environmental and lifestyle risk factors of breast cancer in Malta-a retrospective case-control study. EPMA J 2016;7:20. Doi: 10.1186/s13167-016-0069-z Cauchi JP Camilleri L Scerri C Environmental and lifestyle risk factors of breast cancer in Malta-a retrospective case-control study EPMA J 2016 7 20 20 10.1186/s13167-016-0069-z 28 28 Appel SJ, Cleiment RJ. Identifying women at risk for hereditary breast and ovarian cancer syndrome utilizing breast care nurse navigation at mammography and imaging centers. J Natl Black Nurses Assoc 2015;26(02):17-26 Appel SJ Cleiment RJ Identifying women at risk for hereditary breast and ovarian cancer syndrome utilizing breast care nurse navigation at mammography and imaging centers J Natl Black Nurses Assoc 2015 26 02 17 26