Showing papers in "Journal of Carcinogenesis in 2006"
TL;DR: Elevated levels of ROS and down regulation of ROS scavengers and antioxidant enzymes are associated with various human diseases including various cancers, also implicated in diabtes and neurodegenerative diseases.
Abstract: Oxygen derived species such as superoxide radical, hydrogen peroxide, singlet oxygen and hydroxyl radical are well known to be cytotoxic and have been implicated in the etiology of a wide array of human diseases, including cancer. Various carcinogens may also partly exert their effect by generating reactive oxygen species (ROS) during their metabolism. Oxidative damage to cellular DNA can lead to mutations and may, therefore, play an important role in the initiation and progression of multistage carcinogenesis. The changes in DNA such as base modification, rearrangement of DNA sequence, miscoding of DNA lesion, gene duplication and the activation of oncogenes may be involved in the initiation of various cancers. Elevated levels of ROS and down regulation of ROS scavengers and antioxidant enzymes are associated with various human diseases including various cancers. ROS are also implicated in diabtes and neurodegenerative diseases. ROS influences central cellular processes such as proliferation a, apoptosis, senescence which are implicated in the development of cancer. Understanding the role of ROS as key mediators in signaling cascades may provide various opportunities for pharmacological intervention.
1,353 citations
TL;DR: It is concluded that resveratrol in the diet can reduce susceptibility to mammary cancer, while EGCG in the drinking water at the dose used was not effective.
Abstract: Despite the advent of new and aggressive therapeutics, breast cancer remains a leading killer among women; hence there is a need for the prevention of this disease. Several naturally occurring polyphenols have received much attention for their health benefits, including anti-carcinogenic properties. Two of these are resveratrol, a component of red grapes, and epigallocatechin-3-gallate (EGCG), the major catechin found in green tea. In this study, we tested the hypothesis that these two polyphenols protect against chemically-induced mammary cancer by modulating mammary gland architecture, cell proliferation, and apoptosis. Female Sprague-Dawley CD rats were exposed to either resveratrol (1 g/kg AIN-76A diet), EGCG (0.065% in the drinking water), or control diet (AIN-76A) for the entirety of their life starting at birth. At 50 days postpartum, rats were treated with 60 mg dimethylbenz[a]anthracene (DMBA)/kg body weight to induce mammary cancer. Resveratrol, but not EGCG, suppressed mammary carcinogenesis (fewer tumors per rat and longer tumor latency). Analysis of mammary whole mounts from 50-day-old rats revealed that resveratrol, but not EGCG, treatment resulted in more differentiated lobular structures. Bromodeoxyuridine (BrdU) incorporation studies showed that resveratrol treatment caused a significant reduction in proliferative cells in mammary terminal ductal structures at 50 days postpartum, making them less susceptible to carcinogen insult. The epithelial cells of terminal end buds in the mammary glands of resveratrol-treated rats also showed an increase in apoptotic cells compared to the control or EGCG-treated rats as measured by a DNA fragmentation assay. At the given doses, resveratrol treatment resulted in a serum resveratrol concentration of 2.00 μM, while treatment with EGCG resulted in a serum EGCG concentration of 31.06 nM. 17β-Estradiol, progesterone, and prolactin concentrations in the serum were not significantly affected by resveratrol or EGCG. Neither polyphenol treatment resulted in toxicity as tested by alterations in body weights, diet and drink consumptions, and day to vaginal opening. We conclude that resveratrol in the diet can reduce susceptibility to mammary cancer, while EGCG in the drinking water at the dose used was not effective.
139 citations
TL;DR: The down regulation ofHA expression in tumor cells is associated with progression of tumor from well differentiated through poorly differentiated stage, despite the constant HA expression in the tumor associated stroma.
Abstract: The development and progression of human tumors is accompanied by various cellular, biochemical and genetic alterations. These events include tumor cells interaction with extracellular matrix molecules including hyaluronan (HA). Hyaluronan is a large polysaccharide associated with pericellular matrix of proliferating, migrating cells. Its implication in malignant transformation, tumor progression and with the degree of differentiation in various invasive tumors has well accepted. It has been well known the role HA receptors in tumor growth and metastasis in various cancer tissues. Previously we have observed the unified over expression of Hyaluronic Acid Binding Protein (HABP), H11B2C2 antigen by the tumor cells in various types progressing tumor tissues with different grades. However, the poor understanding of relation between HA and HA-binding protein expression on tumor cells during tumor progression as well as the asymmetric observations of the role of HA expression in tumor progression prompted us to examine the degree of HA expression on tumor cells vs. stroma in various types of human tumors with different grades.
75 citations
TL;DR: The present data indicate that not only could CPP32 provide a potential target for regulation of cytoregR-induced apoptosis but also that cytoreGR could play a significant role in chemotherapeutic regimen in many human malignant tumors.
Abstract: Cancer is one of the devastating neovascular diseases that incapacitate so many people the world over. Recent reports from the National Cancer Institute indicate some significant gain therapy and cancer management as seen in the increase in the 5-year survival rate over the past two decades. Although near-perfect cure rate have been reported in the early-stage disease, these data reveal high recurrence rate and serious side effects including second malignancies and fatalities. Most of the currently used anticancer agents are only effective against proliferating cancer cells. Thus attention has been focused on potential anti-cancer agents capable of killing cancer cells independent of the cell cycle state, to ensure effective elimination of most cancer cells. The objective of this study was to test the chemosensitivity and potential mechanism of action of a novel cancer drug, CytoregR, in a panel of human cancer cells.
61 citations
TL;DR: It is shown that more quantitative knowledge is needed about circadian light exposures actually experienced by women and girls in modern societies, from epidemiological studies and from parametric studies using animal models.
Abstract: Objectives
There is a growing interest in the role that light plays on nocturnal melatonin production and, perhaps thereby, the incidence of breast cancer in modern societies. The direct causal relationships in this logical chain have not, however, been fully established and the weakest link is an inability to quantitatively specify architectural lighting as a stimulus for the circadian system. The purpose of the present paper is to draw attention to this weakness.
51 citations
TL;DR: Protection against DEN-mediated carcinogenic changes in rat liver can be achieved by long term treatment with the decoction comprised of N. sativa seeds, S. glabra rhizome and H. indicus root bark.
Abstract: A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root bark and Smilax glabra rhizome is being recommended for cancer patients by a family of traditional medical practitioners of Sri Lanka. Previous investigations have demonstrated that a short term (10 weeks) treatment with the decoction can significantly inhibit diethylnitrosamine (DEN) mediated expression of Glutathione S-transferase P form (GST-P) in rat liver. The objective of the present investigation was to determine whether long term (16 months) treatment with the decoction would be successful in inhibiting in rat livers, not only DEN- mediated expression of GST-P, but also the carcinogen mediated development of overt tumours (OT) or histopathological changes leading to tumour development (HT).
48 citations
TL;DR: The decreased level of IGFs could be due to the increased levels of IGFBP-3, because of the high binding affinity towards IGFs, thereby decreasing the cell proliferation, and suggesting it may be a p53-independent effector of apoptosis in prostate cancer cells.
Abstract: Quercetin, the predominant flavonoid, has been reported to lower the risk of several cancers. This flavonoid found in onion, grapes, green vegetables, etc. has been shown to possess potent antiproliferative effects against various malignant cells. This study was designed to investigate its effects on insulin-like growth factors (IGFs) and their binding protein-3 (IGFBP-3) proteins secretion and also apoptosis induction in the human prostate cancer cell line, PC-3.
44 citations
TL;DR: Dependent on the histological subtype of lung cancer, PTTG-1 expression was associated with a better outcome in patients with SCLC and a rather unfavourable outcome for patients with NSCLCs, and multivariate analysis using Cox regression confirmed the prognostic relevance of PTTGs expression next to performance status and tumor stage in patientswith NSCLC.
Abstract: PTTG-1 (pituitary tumor transforming gene) is a novel oncogene that is overexpressed in tumors, such as pituitary adenoma, breast and gastrointestinal cancers as well as in leukemia. In this study, we examined the role of PTTG-1 expression in lung cancer with regard to histological subtype, the correlation of PTTG-1 to clinical parameters and relation on patients' survival.
38 citations
TL;DR: The importance of promising dietary intervention agents such as the omega-3 fatty acids as substrate competitors of LA/AA, aimed primarily at high 15-LO-1 and COX-2 as the molecular targets in PCa initiation and/or progression is underscored.
Abstract: One of the major components in high-fat diets (Western diet) is the omega (ω, n)-6 polyunsaturated fatty acid (PUFA) called linoleic acid (LA). Linoleic acid is the precursor for arachidonic acid (AA). These fatty acids are metabolized to an array of eicosanoids and prostaglandins depending upon the enzymes in the pathway. Aberrant expression of the catabolic enzymes such as cyclooxygenases (COX-1 and/or -2) or lipoxygenases (5-LO, 12-LO, 15-LO-1, and 15-LO-2) that convert PUFA either AA and/or LA to bioactive lipid metabolites appear to significantly contribute to the development of PCa. However, PUFA and its cellular interactions in PCa are poorly understood. We therefore examined the mRNA levels of key enzymes involved in the LA and AA pathways in 18 human donor (normal) prostates compared to 60 prostate tumors using the Affymetrix U95Av2 chips. This comparative (normal donor versus prostate cancer) study showed that: 1) the level of 15-LO-1 expression (the key enzyme in the LA pathway) is low (P < 0.001), whereas the levels of delta-5 desaturase (P < 0.001, the key enzyme in the AA pathway), delta-6 desaturase (P = 0.001), elongase (P = 0.16) and 15-lipoxygenase-2 (15-LO-2, P = 0.74) are higher in donor (normal) prostates, and 2) Contrary to the observation in the normal tissues, significantly high levels of only 15-LO-1; whereas low levels of delta-6 desaturase, elongase, delta-5 desaturase and 15-LO-2 respectively, were observed in PCa tissues. Although the cyclooxygenase (COX)-1 and COX-2 mRNA levels were high in PCa, no significant differences were observed when compared in donor tissues. Our study underscores the importance of promising dietary intervention agents such as the omega-3 fatty acids as substrate competitors of LA/AA, aimed primarily at high 15-LO-1 and COX-2 as the molecular targets in PCa initiation and/or progression.
35 citations
TL;DR: 89% of cervical cancers are infected with HPV and 68% also infected with EBV, which means that in cervical cancer stay HPV and EBV.
Abstract: The Early-7 (E7) protein of HPV binds to the underphosphorelated form of the tumor suppressor protein – pRb and displaces the E2F transcription factor that is normally bound by pRb. The latent membrane protein-1 (LMP-1) of EBV prevents apoptosis of B cells by up regulating the expression of bcl-2, and it activates growth promoting pathway that are normally triggered by T cell – derivate signal. The aims of this study to know that in cervical cancer stay HPV and EBV.
29 citations
TL;DR: The short latency for tumor development, the variety of tumor morphology and the liver metastases seen in Ela- myc and MT-tgfα/Ela-myc mice make these animals good models for investigating new therapeutic and preventive strategies for pancreatic cancer.
Abstract: In order to identify good animal models for investigating therapeutic and preventive strategies for pancreatic cancer, we analyzed pancreatic lesions from several transgenic models and made a series of novel findings. Female MT-tgf alpha mice of the MT100 line developed pancreatic proliferation, acinar-ductal metaplasia, multilocular cystic neoplasms, ductal adenocarcinomas and prominent fibrosis, while the lesions in males were less severe. MT-tgf alpha-ES transgenic lines of both sexes developed slowly progressing lesions that were similar to what was seen in MT100 males. In both MT100 and MT-tgf alpha-ES lines, TGF alpha transgene was expressed mainly in proliferating ductal cells. Ela-myc transgenic mice with a mixed C57BL/6, SJL and FVB genetic background developed pancreatic tumors at 2-7 months of age, and half of the tumors were ductal adenocarcinomas, similar to what was reported originally by Sandgren et al 1. However, in 20% of the mice, the tumors metastasized to the liver. MT100/Ela-myc and MT-tgf alpha-ES/Ela-myc double transgenic mice developed not only acinar carcinomas and mixed carcinomas as previously reported but also various ductal-originated lesions, including multilocular cystic neoplasms and ductal adenocarcinomas. The double transgenic tumors were more malignant and metastasized to the liver at a higher frequency (33%) compared with the Ela-myc tumors. Sequencing of the coding region of p16ink4, k-ras and Rb cDNA in small numbers of pancreatic tumors did not identify mutations. The short latency for tumor development, the variety of tumor morphology and the liver metastases seen in Ela-myc and MT-tgf alpha/Ela-myc mice make these animals good models for investigating new therapeutic and preventive strategies for pancreatic cancer.
TL;DR: The findings demonstrate the importance of complete analysis of FasL expression by tumor cells in order to fully characterize its biological function and may help to resolve the discrepancies present in the literature regarding FasLexpression and tumor immune privilege.
Abstract: Background: During carcinogenesis, tumors develop multiple mechanisms for evading the immune response, including upregulation of Fas ligand (FasL/CD95L) expression. Expression of FasL may help to maintain tumor cells in a state of immune privilege by inducing apoptosis of anti-tumor immune effector cells. Recently this idea has been challenged by studies reporting that tumor cells of varying origin do not express FasL. In the present study, we aimed to comprehensively characterize FasL expression in tumors of both murine and human origin over a 72 hour time period. Methods: RNA and protein was extracted from six human (SW620, HT29, SW480, KM12SM, HCT116, Jurkat) and three mouse (CMT93, CT26, B16F10) cancer cell lines at regular time intervals over a 72 hour time period. FasL expression was detected at the mRNA level by RT-PCR, using intron spanning primers, and at the protein level by Western Blotting and immunofluorescence, using a polyclonal FasL- specific antibody. Results: Expression of FasL mRNA and protein was observed in all cell lines analysed. However, expression of FasL mRNA varied dramatically over time, with cells negative for FasL mRNA at many time points. In contrast, 8 of the 9 cell lines constitutively expressed FasL protein. Thus, cells can abundantly express FasL protein at times when FasL mRNA is absent. Conclusion: These findings demonstrate the importance of complete analysis of FasL expression by tumor cells in order to fully characterize its biological function and may help to resolve the discrepancies present in the literature regarding FasL expression and tumor immune privilege.
TL;DR: Evidence is provided that IGF-II, via activation of the β-catenin signaling cascade, promotes growth of ACF and tumors without affecting tumor numbers.
Abstract: In colorectal cancer insulin-like growth factor II (IGF-II) is frequently overexpressed. To evaluate, whether IGF-II affects different stages of tumorigenesis, we induced neoplastic alterations in the colon of wild-type and IGF-II transgenic mice using 1,2-dimethylhydrazine (DMH). Aberrant crypt foci (ACF) served as markers of early lesions in the colonic mucosa, whereas adenomas and carcinomas characterized the endpoints of tumor development. DMH-treatment led initially to significantly more ACF in IGF-II transgenic than in wild-type mice. This increase in ACF was especially prominent for those consisting of ≥three aberrant crypts (AC). Nevertheless, adenomas and adenocarcinomas of the colon, present after 34 weeks in both genetic groups, were not found at different frequency. Tumor volumes, however, were significantly higher in IGF-II transgenic mice and correlated with serum IGF-II levels. Immunohistochemical staining for markers of proliferation and apoptosis revealed increased cell proliferation rates in tumors of IGF-II transgenic mice without significant affection of apoptosis. Increased proliferation was accompanied by elevated localization of β-catenin in the cytosol and cell nuclei and reduced appearance at the inner plasma membrane. In conclusion, we provide evidence that IGF-II, via activation of the β-catenin signaling cascade, promotes growth of ACF and tumors without affecting tumor numbers.
TL;DR: Fish venom peptide was found to selectively induce apoptosis in cancer cell, and did not cause any adverse effect on normal human lymphocytes.
Abstract: The present study is an attempt to evaluate the antiproliferative potential of peptide (7.6 kDa) from lionfish (Pterios volitans) venom on cultured HEp2 and HeLa cells. Different dose of purified peptide (1, 2 and 4 μg/ml) at different time points (12, 24 and 36 hrs) were tested for antiproliferative index of the peptide. Among them, 2 μg/ml at 24 hrs was found to effectively inhibit cancer cell growth in vitro and did not cause any adverse effect on normal human lymphocytes. Apoptosis was examined by propidium iodide staining, confirmed by the expression of caspase-8 and caspase-3, down regulation of Bcl-2 expression and DNA fragmentation in treated cells, when compared to untreated HEp2 and HeLa cells. Thus fish venom peptide was found to selectively induce apoptosis in cancer cell.
TL;DR: Investigating the role of a simple tandem repeat polymorphism (STRP) in the aromatase (CYP19) gene in breast cancer susceptibility in Nigerian women found that harboring the putative high risk genotypes conferred a 29% increased risk of breast cancer when all women in the study were considered.
Abstract: Breast cancer is the most common cancer and the leading cause of cancer related deaths in women worldwide. The incidence of the disease is increasing globally and this increase is occurring at a faster rate in population groups that hirtherto enjoyed low incidence. This study was designed to evaluate the role of a simple tandem repeat polymorphism (STRP) in the aromatase (CYP19) gene in breast cancer susceptibility in Nigerian women, a population of indigenous sub-Saharan African ancestry.
TL;DR: Therapy combining GEM and the HDAC inhibitor PB initiates a spectrum of apoptosis-inducing mitochondrial and further JNK-dependent events, thereby overcoming the therapeutic resistance of NSCLC tumor cells.
Abstract: Standard chemotherapy protocols in NSCLC are of limited clinical benefit. Histone deacetylase (HDAC) inhibitors represent a new strategy in human cancer therapy. In this study the combination of the HDAC inhibitor phenylbutyrate (PB) and the nucleoside analogue gemcitabine (GEM) was evaluated and the mechanisms underlying increased cell death were analyzed.
TL;DR: The diagnosis of invasive gastrointestinal aspergillosis may be considered in a neutropenic patient with acute abdominal symptoms and the emergence of new and powerful immunosuppressive, anticancer drugs and potent antibiotics is concluded.
Abstract: To report a 45 year old lady presenting with proximal jejunal gangrene due to invasive Aspergillosis. The patient was undergoing adjuvant chemotherapy for advance carcinoma of breast (Stage IV).
TL;DR: The objective of this study is to examine the correlation between levels of mRNA expression of IGF- 1 and IGF-1R, and the clinicopathological parameters of breast cancer.
Abstract: The insulin-like growth factor I (IGF-I) has been implicated in breast cancer development acting through insulin-like growth factor I receptor (IGF-IR). The objective of this study is to examine the correlation between levels of mRNA expression of IGF-1 and IGF-1R, and the clinicopathological parameters of breast cancer.
TL;DR: The absence of PSMA expression in CNVM suggests that PSMA may not be a potential target for antineovasculature-based therapy, and supports the theory, previously suggested, that endothelial cell PSma expression may be stimulated by one or more tumor-secreted angiogenic factors.
Abstract: Choroidal neovascular membrane (CNVM) is one of the leading causes of severe visual loss and is often associated with age-related macular degeneration (AMD). Various modalities of treatment, including photocoagulation and surgery, are being considered as options, but with limited success. Prostate-specific membrane antigen (PSMA) is a type II membrane glycoprotein expressed in benign and malignant prostatic tissues, in some non-prostatic tissues, and in the endothelium of tumor-associated neovasculature of non-prostatic neoplasm. Some studies have suggested that the expression of PSMA is restricted to endothelium from tumor-associated neovasculature and might be stimulated by some tumor-secreted angiogenic factors. However, no previous study demonstrating PSMA expression in non-related tumor neovasculature, such as CNVM, has been performed to date. Furthermore, demonstration of PSMA expression in CNVM in AMD patients could reveal a novel target for antineovascular therapy. The purpose of this study was to evaluate the immunohistochemical expression of PSMA in CNVM from AMD.
TL;DR: It is unlikely that mechanisms involving Kupffer cells play an eminent role in the hepatic hyperplasia, and consequently hepatocarcinogenicity attributed to PPARα agonists, based on the current findings showing animals treated with PFOA alone or in combination with methylpalmitate to have similar levels of serum TNFα and IL-1β, which are reliable indicators of K upffer cell activity, despite a remarkable difference in hepatocellular proliferation.
Abstract: It has been proposed that PPARα agonists stimulate Kupffer cells in rodents which in turn, release mitogenic factors leading to hepatic hyperplasia, and eventually cancer. However, Kupffer cells do not express PPARα receptors, and PPARα agonists stimulate hepatocellular proliferation in both TNFα- and TNFα receptor-null mice, casting doubt on the involvement of Kupffer cells in the mitogenic response to PPARα agonists. This study was therefore designed to investigate whether the PPARα agonist PFOA and the Kupffer cell inhibitor methylpalmitate produce opposing effects on hepatocellular proliferation and Kupffer cell activity in vivo, in a manner that would implicate these cells in the mitogenic effects of PPARα agonists.
TL;DR: The application of RT-PCR on cDNA and DNased cDNA samples and control groups was used to detect the expression of hTR, GAPDH and PGM1 genes and a significant association between hTR expression and telomerase activity was observed.
Abstract: Telomerase is a ribonucleoprotein enzyme that compensates for the telomere length shortening which occurs during the cell cycle. Telomerase activity has been detected in most tumours but not in somatic cells. However, hTR; the RNA component of telomerase; has been reported to be universally expressed in both cancerous and non-cancerous tissues. Tumour samples from 50 patients with primary invasive breast cancer were collected. The TRAP assay was used to detect telomerase activity. RT-PCR on cDNA and DNased cDNA samples and control groups was used to detect the expression of hTR, GAPDH and PGM1 genes. Seventy-two percent of samples showed telomerase activity. DNA contamination was detected in 36 (72%) of RNA samples. Without performing DNase treatment, 49 (98%) of all samples showed hTR expression, but with the application of this strategy, hTR expression decreased from 98% to 64%. A significant association (p < 0.001) between hTR expression and telomerase activity was observed. Among the 32 hTR positive samples, 30 had telomerase activity and among the 18 hTR negative samples, telomerase activity was observed in 6 cases. Thus the application of this strategy could provide an applicable tool to use instead of the TRAP assay thus facilitating telomerase research in cancer genetic investigations.
TL;DR: Asbestos exposure can develop genotoxic effects and damage in the pleura and lungs as mentioned in this paper, and it is also associated with increased rate of other organ malignancies, such as lung cancer.
Abstract: Environmental asbestos exposure can cause the grave lung and pleura malignancies with a high mortality rate, and it is also associated with increased rate of other organ malignancies. Asbestos exposure can develop genotoxic effects and damage in the pleura and lungs.
TL;DR: The single concentration of CHL tested in this study had no significant effects on AFB1-induced foci of the liver and colons of rats and the post-initiation effects ofCHL towards aflatoxin B1 (AFB1)-induced preneoplastic foci in rats were no significant.
Abstract: Chlorophyllin (CHL) is a promising chemopreventive agent believed to block cancer primarily by inhibiting carcinogen uptake through the formation of molecular complexes with the carcinogens. However, recent studies suggest that CHL may have additional biological effects particularly when given after the period of carcinogen treatment. This study examines the post-initiation effects of CHL towards aflatoxin B1 (AFB1)-induced preneoplastic foci of the liver and colon. The single concentration of CHL tested in this study (0.1% in the drinking water) had no significant effects on AFB1-induced foci of the liver and colons of rats.
TL;DR: This study mapped the complete methylation status of the hMSH2 promoter, a region that contains 75 CpG sites, using bisulfite genomic sequencing in 60 primary colorectal cancers and demonstrated that h MSH2 hypermethylation and protein expression were associated with the development of coloreCTal cancer.
Abstract: The detailed methylation status of CpG sites in the promoter region of hMSH2 gene has yet not to be reported. We have mapped the complete methylation status of the hMSH2 promoter, a region that contains 75 CpG sites, using bisulfite genomic sequencing in 60 primary colorectal cancers. And the expression of hMSH2 was detected by immunohistochemistry. The hypermethylation of hMSH2 was detected in 18.33% (11/60) of tumor tissues. The protein of hMSH2 was detected in 41.67% (25/60) of tumor tissues. No hypermethylation of hMSH2 was detected in normal tissues. The protein of hMSH2 was detected in all normal tissues. Our study demonstrated that hMSH2 hypermethylation and protein expression were associated with the development of colorectal cancer.
TL;DR: Evidence is found to support an interaction between catechol-O-methyltransferase genotype and tobacco smoke exposure in breast cancer etiology.
Abstract: Women with homozygous polymorphic alleles of catechol-O-methyltransferase (COMT-LL) metabolize 2-hydroxylated estradiol, a suspected anticarcinogenic metabolite of estrogen, at a four-fold lower rate than women with no polymorphic alleles (COMT-HH) or heterozygous women (COMT-HL). We hypothesized that COMT-LL women exposed actively or passively to tobacco smoke would have higher exposure to 2-hydroxylated estradiol than never-active/never passive exposed women, and should therefore have a lower risk of breast cancer than women exposed to tobacco smoke or with higher COMT activity.