Unbalanced estrogen metabolism in ovarian cancer

Greater exposure to estrogens is a risk factor for ovarian cancer. To investigate the role of estrogens in ovarian cancer, a spot urine sample and a saliva sample were obtained from 33 women with ovarian cancer and 34 age‐matched controls. Thirty‐eight estrogen metabolites, conjugates and DNA adducts were analyzed in the urine samples using ultraperformance liquid chromatography/tandem mass spectrometry, and the ratio of adducts to metabolites and conjugates was calculated for each sample. The ratio of depurinating estrogen–DNA adducts to estrogen metabolites and conjugates was significantly higher in cases compared to controls (p < 0.0001), demonstrating high specificity and sensitivity. DNA was purified from the saliva samples and analyzed for genetic polymorphisms in the genes for two estrogen‐metabolizing enzymes. Women with two low‐activity alleles of catechol‐O‐methyltransferase plus one or two high‐activity alleles of cytochrome P450 1B1 had higher levels of estrogen–DNA adducts and were more likely to have ovarian cancer. These findings indicate that estrogen metabolism is unbalanced in ovarian cancer and suggest that formation of estrogen–DNA adducts plays a critical role in the initiation of ovarian cancer.     

The role of menopausal hormone therapy in women with or at risk of ovarian and breast cancers: Misconceptions and current directions

For women who are candidates for menopausal hormone therapy (MHT), estrogen can provide relief from symptomatic menopause, decrease rates of chronic illnesses, and improve health-related quality of life. However, confusion surrounds the evidence regarding the impact of exogenous estrogen and progesterone on the breast and ovary. Available data regarding the risks of MHT (estrogen and/or progestin) related to the development of breast and ovarian cancer are often inconsistent or incomplete. Modern molecular and genetic techniques have improved our understanding of the heterogeneity of breast and ovarian cancer. This enhanced understanding of the disease has impacted our understanding of carcinogenesis. Treatment options have evolved to be more targeted toward hormonal therapy for certain subtypes of disease, whereas cytotoxic chemotherapy remains the standard for other histological and molecular subtypes. The role of MHT in the breast and ovarian cancer survivor, as well as women who are at high risk for the development of hereditary breast and ovarian cancer, remains controversial despite evidence that this treatment can improve quality of life and survival outcomes. Through this article, we examine the evidence for and against the use of MHT with a focus on women who have or are at high risk for breast and ovarian cancer.     

The effect of estrogen vs. combined estrogen-progestogen therapy on the risk of colorectal cancer

Studies suggest that estrogen therapy (ET) and combined estrogen-progestogen therapy (EPT) may have different associations with colorectal cancer (CRC) risk, but data are conflicting. Prior meta-analyses did not distinguish between ET and EPT. We conducted a meta-analysis to summarize the relative risks (RR) of CRC due to ET versus EPT among peri- or postmenopausal women. From a total of 2,661 articles, four randomized controlled trials, eight cohort and eight case-control studies were included. Variables assessed included study characteristics, duration and recency of menopausal hormone therapy (HT) use, method of assessment of HT use, outcome definition and its ascertainment method. RRs were synthesized by random-effects models. We found that EPT ever use was associated with a decreased risk of CRC (RR 0.74, 95% CI 0.68-0.81), and so was ET ever use (RR 0.79, 95% CI 0.69-0.91). While current use of ET was associated with a significantly reduced risk of CRC (RR 0.70, 95% CI 0.57-0.85), former use was not (RR 0.86, 95%CI 0.67-1.11). Recency did not significantly modify the association between EPT and CRC risk. EPT former use was associated with a lower RR of CRC compared to ET former use (p = 0.008) but no such difference was observed between EPT and ET current use (p = 0.12). Overall, we found consistent evidence supporting the association between EPT and CRC risk reduction, regardless of recency. While literature for the association between ET and CRC risk is heterogeneous, our analyses suggest only current use of ET is associated with a decreased CRC risk.     

Estrogen and estrogen-progestin replacement therapy and risk of postmenopausal breast cancer in Canada

Objective: To examine the association between hormone replacement therapy (HRT) use and breast cancer incidence and to determine whether the association differs according to type of regimen. Method: Data were collected in Ontario from 404 incident cases and 403 age frequency-matched controls, between 1995 and 1996, using a self-administered questionnaire. Results: Multivariate analyses revealed an elevated odds ratio among long-term (ten years) HRT users (odds ratio (OR) = 1.80, 95% confidence interval (CI) 1.06–3.06). Risk among long-term estrogen–progestin users was substantially higher (OR = 3.48, 95% CI 1.00–12.11) than risk among long-term users of estrogen alone (OR = 1.74, 95% CI 0.93–3.24). Among both estrogen and estrogen–progestin users, positive associations were not observed for durations of use less than ten years. Conclusion: These data suggest that long-term use of HRT increases the risk of breast cancer and that estrogen–progestin therapy may be more detrimental than estrogen use alone.     

An overview of menopausal oestrogen-progestin hormone therapy and breast cancer risk

Results from the Women's Health Initiative (WHI) trial support findings from observational studies that oestrogen-progestin therapy (EPT) use is associated with an increase in breast cancer risk. We conducted a meta-analysis using EPT-specific results from the Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) pooled analysis and studies published since that report to obtain an overview of EPT use and breast cancer risk. We also assessed risk by histologic subtype of breast cancer, by schedule of the progestin component of EPT, and by recency of use. We estimate that overall, EPT results in a 7.6% increase in breast cancer risk per year of use. The risk was statistically significantly lower in US studies than in European studies - 5.2 vs 7.9%. There was a significantly higher risk for continuous-combined than for sequential EPT use in Scandinavian studies where much higher total doses of progestin were used in continuous-combined than in sequential EPT. We observed no overall difference in risk for lobular vs ductal carcinoma but did observe a slightly higher risk for current vs past EPT use.     

激素受体与卵巢癌预后、发病机制及治疗的研究进展

卵巢癌作为恶性程度最高的妇科肿瘤,在肿瘤靶向治疗方面已取得了一定进展。激素疗法在乳腺癌治疗中的成功应用,使激素受体成为靶向治疗的首要研究方向。卵巢癌不同病理类型对激素的敏感性不同是激素疗法对卵巢癌治疗效果不同的根本原因。本文对卵巢癌激素受体的表达及其表达对预后的影响、发病机制的研究及临床治疗做综述。     

A prospective study of postmenopausal hormone use and ovarian cancer risk

The relationship between postmenopausal hormone use (PMH) and ovarian cancer risk is unclear, particularly for specific hormone formulations, but recent studies suggest that there is a positive association. We conducted a prospective observational study with 82,905 postmenopausal women, including 389 ovarian cancers, in the Nurses' Health Study from 1976 to 2002. Compared with never users of PMH, both current and past users of > or =5 years had a significantly elevated risk of ovarian cancer (RR=1.41, 95% confidence interval (CI) 1.07-1.86 and relative risk (RR)=1.52, 95% CI 1.01-2.27, respectively). Examined by hormone type in continuous years, use of unopposed estrogen was associated with a significant increase in the risk of epithelial ovarian cancer (P for trend <0.001; RR for 5-year increment of use=1.25, 95% CI 1.12-1.38). Use of estrogen plus progestin (RR for 5-year increment of use=1.04, 95% CI 0.82-1.32) was not significantly associated with ovarian cancer risk. Generally, results were similar for serous tumours (RR for 5-year increment of unopposed estrogen use=1.23, 95% CI 1.07-1.40) and slightly stronger for endometrioid tumours (RR for 5-year increment of unopposed estrogen use=1.53, 95% CI 1.20-1.94). Recency of use was not significantly associated with ovarian cancer risk, but statistical power was limited here.     

Polymorphisms in genes of the steroid receptor superfamily modify postmenopausal breast cancer risk associated with menopausal hormone therapy

Menopausal hormone therapy (HT) is associated with increased breast cancer risk among postmenopausal women. Nuclear receptors are involved in steroid hormone‐ and xenobiotic‐mediated signal transduction playing a crucial role in regulating gene expression. Therefore, variations within these genes may influence HT‐associated breast cancer risk. We investigated 3,149 postmenopausal breast cancer patients and 5,489 controls from 2 German population‐based case‐control studies. Thirty‐three polymorphisms selected on the basis of known or putative functional relevance located in ESR1, ESR2, PGR, PXR and AR were genotyped. Conditional logistic regression was used to assess multiplicative statistical interaction between polymorphisms and duration of estrogen–progestagen therapy and of estrogen monotherapy with regard to breast cancer risk assuming log‐additive and codominant modes of inheritance. We observed an increased risk for women carrying short AR_(CAG) alleles of <22 repeats associated with combined estrogen–progestagen therapy compared with those with long alleles (≥22 repeats) (p_interaction = 0.03). Additionally, risk associated with combination therapy use was significantly modified by 2 PXR polymorphisms with reduction of risk effects in carriers of the minor PXR_rs6785049_G and PXR_rs1054191_A alleles (p_interaction = 0.04 and 0.05, respectively). Variants in both ESR1 and ESR2 modified risk associated with estrogen monotherapy use. Higher risk were observed in homozygotes for the major ESR1_rs910416_T allele (p_interaction < 0.01) and in homozygotes for the minor ESR2_rs1271572_T, major ESR2_rs4986938_G and minor ESR2_rs928554_G alleles (p_interaction = 0.02, 0.05, 0.02, respectively). Risk effect modification by ESR1_rs910416 and AR_(CAG)n polymorphisms remained significant after correction for multiple testing. We conclude that genetic variants in nuclear receptor genes may modify HT‐associated postmenopausal breast cancer risk.     

Obesity, hormone therapy, estrogen metabolism and risk of postmenopausal breast cancer

Hormone therapy (HT) and body mass index (BMI) have been associated with postmenopausal breast cancer. Because estrogen metabolism may affect breast cancer risk and can be altered by weight and HT, it might play a role in the HT-BMI-breast cancer associations. We undertook a nested case-control study within the Observational Study of the Women's Health Initiative. Baseline levels of 2- and 16alpha-hydroxy estrone (2-OHE1 and 16alpha-OHE1) were measured in 200 women who developed breast cancer during follow-up and 200 healthy controls matched to cases by ethnicity, enrollment date, clinic site, type of HT and years since menopause. Wilcoxon nonparametric tests were used to compare estrogen metabolite levels between cases and controls. Conditional logistic regression was used to assess the relationship between BMI, estrogen metabolites and breast cancer risk. 16alpha-OHE1 levels were modestly but significantly higher in HT users among cases (median 356 pg/ml vs. 315 pg/ml) and controls (354 pg/ml vs. 298 pg/ml). 2-OHE1 levels were substantially and significantly higher in HT users among cases (369 pg/ml vs. 125 pg/ml) and controls (347 pg/ml vs. 134 pg/ml). For non-HT users only, greater BMI and higher 16alpha-OHE1 levels were individually and jointly associated with increased breast cancer risk (OR for women with high BMI and high 16alpha-OHE1 compared to those with low BMI and low 16alpha-OHE1 = 3.51, 95% CI = 1.34-9.16). No associations between BMI, estrogen metabolism and breast cancer risk were found for HT users. Estrogen metabolism differs according to both BMI and HT use, potentially explaining the interaction between BMI and HT in relation to breast cancer risk.     

Cigarette smoking and risk of epithelial ovarian cancer (Australia)

Objectives: We studied the association between cigarette smoking and ovarian cancer in a population-based case–control study. Methods: A total of 794 women with histologically confirmed epithelial ovarian cancer who were aged 18–79 years and resident in one of three Australian states were interviewed, together with 855 controls aged 18–79 years selected at random from the electoral roll from the same states. Information was obtained about cigarette smoking and other factors including age, parity, oral contraceptive use, and reproductive factors. We estimated the relative risk of ovarian cancer associated with cigarette smoking, accounting for histologic type, using multivariable logistic regression to adjust for confounding factors. Results: Women who had ever smoked cigarettes were more likely to develop ovarian cancer than women who had never smoked (adjusted odds ratio (OR) = 1.5; 95% confidence interval (CI) = 1.2–1.9). Risk was greater for ovarian cancers of borderline malignancy (OR = 2.4; 95% CI = 1.4–4.1) than for invasive tumors (OR = 1.7; 95% CI = 1.2–2.4) and the histologic subtype most strongly associated overall was the mucinous subtype among both current smokers (OR = 3.2; 95% CI = 1.8–5.7) and past smokers (OR = 2.3; 95% CI = 1.3–3.9). Conclusions: These data extend recent findings and suggest that cigarette smoking is a risk factor for ovarian cancer, especially mucinous and borderline mucinous types. From a public health viewpoint, this is one of the few reports of a potentially avoidable risk factor for ovarian cancer.     

Menopausal hormone therapy treatment options and ovarian cancer risk: A Swedish prospective population-based matched-cohort study

Although menopausal hormone therapy (MHT) seemingly increases the risk of ovarian cancer, evidence is insufficient whether the risk varies between various MHT formulations, regimens and administration modes. With the aim of filling these knowledge gaps, we investigated the effect of different MHT treatment options on the risk of ovarian cancer. This prospective Swedish population-based matched-cohort study included all women ≥40 years having used systemic MHT between 2005 and 2012 (288,950 ever-users), group-level matched (1:3) to 866,546 nonusers. MHT use was ascertained from the Swedish Prescribed Drug Registry and data was linked to several national health data registries. Multivariable conditional logistic regression provided odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for parity, and comorbidities. Current EP-MHT use was associated with a modestly increased risk of ovarian cancer (OR = 1.38, 95% CI 1.18–1.62), while no consistent risk was found among past users (OR = 1.00, 95% CI 0.84–1.18). Current continuous testosterone derived (OR = 1.50, 95% CI 1.15–1.96) regimens increased the risk whereas progesterone derived (OR = 1.48, 95% CI 1.00–2.21) regimens increased the risk marginally. Nonsignificant positive associations were observed for sequential regimens (OR = 1.87, 95% CI 0.70–5.08; OR = 1.54, 95% CI 0.96–2.47, respectively). An inverse relationship was observed for all E-MHT use (OR = 0.25, 95% CI 0.22–0.29), but this association might partly be explained by underreporting of oophorectomies or tubal ligations. Current cutaneous EP-MHT (OR = 1.28, 95% CI 0.81–2.02) suggested a possibly lower risk than oral MHT (OR = 1.48, 95% CI 1.25–1.75). In conclusion EP-MHT, notably continuous regimens, were associated with a modestly increased risk of ovarian cancer. The role of E-MHT requires further clarification.     

Direct comparisons of adjuvant endocrine therapy, chemotherapy, and chemoendocrine therapy for operable breast cancer patients stratified by estrogen receptor and menopausal status

Based on estrogen receptor (ER) and menopausal status, operable breast cancer (UICC stage I, II, III-a) patients were randomized for adjuvant endocrine therapy, chemotherapy, and chemoendocrine therapy, and the effects on the relapse-free survival (RFS) and overall survival (OS) were compared. Tamoxifen (TAM) 20 mg/day was administered orally for 2 years after mastectomy as an adjuvant endocrine therapy in postmenopausal patients. In premenopausal patients, oophorectomy (OVEX) was performed before TAM administration. In the chemotherapy arm (CHEM), patients were given 0.06 mg/kg of body weight of mitomycin C (MMC) intravenously, followed by an oral administration of cyclophosphamide (CPA) 100 mg/day in an administration of a 3-month period and a 3-month intermission. This 6-month schedule was repeated 4 times in 2 years. The chemoendocrine arm (CHEM + TAM) was composed of TAM with MMC + CPA chemotherapy. The patients were randomized according to ER and menopausal status. ER-positive patients were randomized to three arms: OVEX ± TAM, CHEM, and CHEM + TAM. For ER-negative patients there were two arms: CHEM and CHEM + TAM. 1579 patients entered the trial between September 1978 and December 1991, with median follow-up of 8.2 years. In ER-positive, premenopausal patients, there were no significant differences in RFS or OS among OVEX ± TAM, MMC + CPA, TAM + MMC + CPA arms. On the contrary, in ER-positive, postmenopausal patients, the chemoendocrine therapy showed a significantly higher RFS (p = 0.0400) and OS (p=0.0187) as compared with TAM to chemotherapy alone. There were no significant differences in RFS or OS by addition of TAM on the chemotherapy, in both pre- and post-menopausal ER-negative patients. It was concluded that in ER-positive premenopausal breast cancer, endocrine therapy alone may be equivalent in prolonging RFS and OS to chemotherapy or chemoendocrine therapy, and that ER-positive postmenopausal breast cancer may be better controlled with the combination of TAM and chemotherapy, as compared to TAM or chemotherapy alone. The importance of stratification of operable breast cancer by ER and menopausal status, as well as the direct comparisons of different treatments, were stressed.This revised version was published online in October 2005 with corrections to the Cover Date.     

Copy number variations of GSTT1 and GSTM1, colorectal cancer risk and possible effect modification of cigarette smoking and menopausal hormone therapy

Copy number variations (CNVs) of the glutathione-S-transferase θ-1 (GSTT1) and glutathione-S-transferase μ-1 (GSTM1) gene loci can lead to complete lack of enzyme and have been associated with colorectal cancer (CRC) risk. As GSTs are involved in the detoxification of xenobiotics, CNVs may modify CRC risk associated with smoking exposure and menopausal hormone therapy (MHT) use. We investigated CRC risk associated with GSTT1 and GSTM1 CNVs and their interaction with smoking in 1,796 cases and 1,806 age-, sex- and residence-matched controls from a German population-based case-control study (DACHS). The interaction with MHT was assessed in the subset of 684 postmenopausal female cases and 681 controls. Trimodular genotypes (0/0, 1/0 and 1/1) were determined with relative quantification based on multiplex real-time polymerase chain reaction. The associations with CRC risk as well as possible effect modifications were evaluated using conditional logistic regression analysis. CNVs of GSTT1 and GSTM1 were not significantly associated with CRC risk. Compared to the 1/1 genotype, odds ratios (ORs) for the 0/1 genotype and the 0/0 genotype were 0.89 [95% confidence interval (CI): 0.77-1.04] and 0.97 (95% CI: 0.80-1.18) for GSTT1, and 0.99 (95% CI: 0.78-1.27) and 1.03 (95% CI: 0.81-1.31) for GSTM1. Compared to the non-null genotype, ORs for the null-genotype were 1.04 (95% CI: 0.87-1.23) for GSTT1 and 1.03 (95% CI: 0.91-1.18) for GSTM1. No significant interaction with smoking and MHT use was observed. Our study does not provide evidence for a strong association between CRC risk and CNVs of GSTT1 or GSTM1 or for an effect modification of smoking or MHT use.     

Inverse associations of dietary fiber and menopausal hormone therapy with colorectal cancer risk in the Multiethnic Cohort Study

In the Multiethnic Cohort Study, we previously reported that dietary fiber intake was inversely associated with colorectal cancer risk in men only. In women, the inverse relationship was weaker and appeared to be confounded by menopausal hormone therapy (MHT). We re‐examined this observation with a greatly increased power. Using Cox proportional hazards models, we analyzed data from 187,674 participants with 4,692 cases identified during a mean follow‐up period of 16 years. In multivariable‐adjusted models, dietary fiber intake was inversely associated with colorectal cancer risk in both sexes: HR = 0.73, 95% CI: 0.61–0.89 for highest vs. lowest quintile, p_trend = 0.0020 in men and HR = 0.76, 95% CI: 0.62–0.91, p_trend = 0.0067 in women. Postmenopausal women who ever used MHT had a 19% lower risk of colorectal cancer (95% CI: 0.74–0.89) compared with MHT never users. In a joint analysis of dietary fiber and MHT, dietary fiber intake was associated with a lower colorectal cancer risk in MHT never users (HR = 0.75, 95% CI: 0.59–0.95, p_trend = 0.045), but did not appear to further decrease the colorectal cancer risk of MHT ever users (p_trend = 0.11). Our results support the overall protective roles of dietary fiber and MHT against colorectal cancer and suggest that dietary fiber may not lower risk further among women who ever used MHT. If confirmed, these results would suggest that MHT and dietary fiber may share overlapping mechanisms in protecting against colorectal cancer.     

siRNA在卵巢癌靶向治疗中的研究进展

小干扰RNA(siRNA)可以以高度精确的方式诱导基因沉默,因此可用作研究体内和体外单基因功能的工具,也可成为潜在的新靶向治疗药物.卵巢癌是目前最致命的妇科恶性肿瘤,治疗选择有限,需要改进的靶向疗法来对抗卵巢癌.近些年来,siRNA在卵巢癌靶向治疗中的研究越来越受到关注,本文将对siRNA在卵巢癌靶向治疗中的研究进展展...     

Sedentary behaviours and epithelial ovarian cancer risk

OBJECTIVE: To investigate the effects of sedentary behaviours on the risk of epithelial ovarian cancer. METHODS: A case-control study was conducted in China during 1999-2000. Cases were 254 patients with histologically confirmed epithelial ovary cancer. The 652 controls comprised 340 hospital visitors, 261 non-neoplasm hospital outpatients, and 51 women recruited from the community. The daily sitting duration in both occupational- and leisure-time was measured using a validated questionnaire. The risks of ovarian cancer were assessed using multivariate logistic regression analysis accounting for demographic characteristics, body mass index, familial factors, hormonal status, family ovarian cancer history, physical activity (as weekly metabolic equivalent tasks), and total energy intake. RESULTS: Prolonged sitting duration was associated with an increase in ovarian cancer risk. The odds ratios were, respectively, 1.96 (95% confidence interval (CI): 1.2-3.2) with a significant trend (p = 0.007), 3.39 (95% CI: 1.0-11.5), and 1.77 (95% CI: 1.0-3.1) for high level versus low level of sitting at work, sitting while watching television and total sitting duration. CONCLUSION: Sedentary behaviours were associated with an increase in epithelial ovarian cancer risk.     

妇科恶性肿瘤术后激素替代治疗的研究进展

激素替代治疗（menopausal hormone therapy,MHT）是缓解绝经后患者更年期症状的有效疗法,妇科恶性肿瘤术后患者使用MHT的安全性和有效性是临床上持续关注的重点问题。本文回顾近5年妇科恶性肿瘤术后MHT的相关临床研究,综合结果表明,早期子宫内膜癌（endometrial cancer,EC）术后行MHT不增加复发风险,且有利于提高生活质量。上皮性卵巢癌（ovarian cancer,OC）患者术后MHT对无病生存期和总生存期无不利影响,但不建议用于卵巢性索间质肿瘤等非上皮性卵巢肿瘤。宫颈鳞状细胞癌术后MHT相对安全,但关于宫颈腺癌、外阴癌、阴道癌患者术后使用MHT的研究较少,目前暂无确切结论。本综述旨在更新对妇科恶性肿瘤术后激素治疗的认识,为临床上合理选择MHT方案提供参考,以进一步提高患者生活质量。     

Effects of menopausal hormone therapy-based on the role of estrogens,progestogens, and their metabolites in proliferation of breast cancer cells

Menopausal hormone therapy (MHT) has been widely used for the clinical treatment of symptoms associated with menopause in women. However, the exact nature of the relationship between MHT and the increased risk of breast cancer has not been fully elucidated. The results of the Women’s Health Initiative’s randomized controlled clinical studies showed that estrogen monotherapy was associated with a lower incidence of breast cancer as compared to estrogen-progesterone combined therapy, with an elevated risk of breast cancer. The evidence currently available from randomized trials and observational studies is based on data from different populations, drug formulations, and routes of administration. Even though the risks of MHT and breast cancer have received a great deal of attention, information regarding the unpredictable toxicological risks of estrogen and progestogen metabolism needs to be further analyzed. Furthermore, the diversity and complexity of the metabolic pathways of estrogen and different progestogens as well as the association of the different estrogen and progestogen metabolites with the increased risk of breast cancer need to be adequately studied. Therefore, this review aimed to describe the biological effects of estrogen, progesterone, and their metabolites on the proliferation of breast cancer cells, based on relevant basic research and clinical trials, to improve our understanding of the biological functions of estrogen and progestogen as well as the safety of MHT.