肥胖与乳腺癌

 肥胖被证实是乳腺癌等恶性肿瘤的危险因素之一。大量流行病学资料显示肥胖与乳腺癌的发生发展密切相关,其发病机制可涉及雌激素、胰岛素、瘦素、脂联素、炎症因子等肥胖相关因子。因此,维持正常体重可能有助于乳腺癌的防治。     

脂肪因子与乳腺癌关系研究进展

 近年来,对肥胖与乳腺癌关系的研究不断深入,肥胖的乳腺癌患者比体质量正常患者的预后差,肥胖的乳腺癌患者体质量变化与其复发相关。在这一过程中脂肪因子的作用不容忽视。文章就脂肪因子对细胞增殖、血管新生及乳腺癌预后的影响等方面作一综述。     

肥胖与乳腺癌关系的研究进展

乳腺癌目前已成为全球女性最常见的恶性肿瘤之一,其发病率和死亡率在女性恶性肿瘤中位居第二。大量临床研究和流行病学资料已证实肥胖与乳腺癌的发生、发展密切相关,其发病机制可能涉及雌激素、胰岛素、胰岛素样生长因子-1（IGF-1）、瘦素、脂联素、炎症因子等多种肥胖相关因子。近年来的研究对肥胖促进乳腺癌发展的机制进行了深入分析,并进一步了解到肥胖对乳腺癌的诊断结果、肿瘤特点、治疗以及预后可产生重要影响。因此,控制体重可能是预防复发转移的积极措施,维持正常体重有助于乳腺癌的防治。     

肥胖与肿瘤

肥胖是乳腺癌、大肠癌等多种肿瘤发生的危险因素.研究表明,肥胖通过胰岛素和胰岛素样生长因子-1(IGF-1)、瘦素、脂肪细胞因子、性激素等多种因子影响癌症的发生和发展.研究肥胖与癌症发生发展中的作用及机制将为肿瘤的预防和治疗提供新的思路.     

肥胖影响乳腺癌的研究进展

摘 要：研究表明肥胖可能会影响乳腺癌的发病和预后,但是影响机制尚未明确。本文搜集整理了近年来肥胖与不同绝经状态、不同分子亚型乳腺癌之间发病和预后的关系研究。其中肥胖对绝经前和绝经后乳腺癌的影响是不同的,同时肥胖对不同分子亚型乳腺癌患者发病和预后的影响亦是不同的,并且肥胖合并糖尿病等其他疾病也导致乳腺癌的预后更差。本文对这些文献加以总结并搜集了一些肥胖对乳腺癌发病机制影响的相关研究,可对肥胖与乳腺癌之间关系的基础研究和临床工作提供更多的参考依据。     

脂联素及其受体在肥胖相关的乳腺癌中的作用

肥胖指脂肪组织在体内异常或过度的蓄积。它影响着女性常见的恶性肿瘤之一乳腺癌的发生、发展及治疗效果和预后。脂肪组织可产生多种细胞因子,其中脂联素在肥胖相关的乳腺癌中发挥着重要作用。流行病学研究表明,血浆或血清脂联素水平与肥胖相关的乳腺癌的关系受患者月经状态、乳腺癌家族史、体质指数等因素的影响。脂联素对乳腺癌的作用主要体现在阻止细胞增殖和促进细胞凋亡、参与肿瘤细胞的血管化、影响乳腺癌细胞的侵袭性等方面。进一步明确脂联素在肥胖相关的乳腺癌中的作用机制,有可能为乳腺癌的预防或治疗提供一个新的突破口。     

肥胖与乳腺癌关系的研究进展

乳腺癌是世界女性最常见的恶性肿瘤之一,每年新确诊的癌症病例中有1/10是女性乳腺癌,每年约有120万女性罹患乳腺癌,约50万人死于该病[1]。资料显示,全世界有9.8%的男性和13.8%的女性被认为是肥胖者[2]。肥胖已经成为全球的重大公共卫生问题,同时,流行病学资料显示肥胖能增加乳腺癌风险[3],因而肥胖与乳腺癌的关系日益受到学者们的重视。本文从肥胖人群中乳腺癌患者的临床及生物学机制等方面对肥胖与乳腺癌的研究进展作一综述。     

肥胖与乳腺癌预后的关系

目的 探讨肥胖对乳腺癌颈后的影响。方法 用身体指数(体重(公斤)/身高(米)判断病人的胖瘦,分成消瘦组、普通组、肥胖组,比较各组乳腺癌病人的分布及治疗后的5年生存率。结果 (1)512例乳腺癌病人中肥胖病人占67％。(2)消瘦组5年生存率是78.3％而肥胖组5年生存率是57.8％,两者差异显著(P<0.01)。结论 肥胖可以作为预示乳腺癌发病及判断乳腺癌病人预后的因素。     

代谢综合征与乳腺癌的关系

代谢综合征(metabolic syndrome,MS)是以肥胖和胰岛素抵抗为中心的多种代谢性危险因素在个体内集结的状态,主要组分包括肥胖、高血糖、高胰岛素血症、血脂异常和高血压等。研究表明代谢综合征不仅是心血管病的危险因素,还与乳腺癌的发生和预后相关。本文综述代谢综合征与乳腺癌患病风险的关系及其致乳腺癌的可能机制,为乳腺癌的预防、治疗及预后提供新的策略。     

脂肪细胞因子与乳腺癌

肥胖与绝经后乳腺癌的发病、晚期病变和预后明显相关,绝经后肥胖女性雌激素水乎的升高被认为是其主要的机制之一。脂肪细胞因子是白色脂肪细胞分泌的多种激素和细胞因子,研究发现其与乳腺癌细胞的增殖、浸润、转移和血管生成有关,提示其可能是肥胖与乳腺癌关系的生物学基础。     

Breast cancer prevention: present and future

Increased risk of breast cancer may result from modifiable factors such as endogenous hormone levels, obesity, HRT, and non-lactation, or non-modifiable factors such as genetic susceptibility or increasing age. Those factors that are easiest to modify may have a limited impact on the totality of breast cancer. The Gail model, based on known factors may be useful for estimating life-time risk in some individuals. Tamoxifen prevention still remains contentious. In the NSABP-P1 study, there was a 49% reduction in risk of breast cancer in women given tamoxifen but in the Italian and Royal Marsden trials, no effect on breast cancer incidence was detected, possibly because of the different case-mix in these studies. Raloxifene, tested in the MORE trial reduced the incidence of breast cancer by 65%. The effect was restricted to ER positive tumours: no reduction in ER negative cancers was seen. Life-style factors such as diet, obesity, exercise, and age of first full term pregnancy and number of pregnancies have a mild to moderate impact on risk and so may have little effect on the incidence of breast cancer. Reduction of alcohol intake could lead to a modest reduction in the risk of breast cancer but possibly adversely affect other diseases. So far, studies of retinoids have not shown a benefit in terms of breast cancer risk reduction. Fat reduction and GnRH analogues reduce mammographic density but have not yet been shown to affect risk.     

Review of anthropometric factors and breast cancer risk.

Epidemiological evidence implicating anthropometric risk factors in breast cancer aetiology is accumulating. For premenopausal women, breast cancer risk increases with increasing height, but decreases with higher weight or body mass index, and no association with increased central adiposity exists. For postmenopausal women, an increased risk of breast cancer is found with increasing levels of all the anthropometric variables including height, weight, body mass index, waist-hip ratio, waist circumference and weight gain. Weight loss appears to decrease risk, particularly if it occurs later in life. Breast size may be a risk factor for breast cancer, however, the current evidence is inconclusive. Several hypothesized biologic mechanisms exist to explain how anthropometric factors influence breast cancer risk. Obesity may increase levels of circulating endogenous sex hormones, insulin and insulin-like growth factors that all, in turn, increase breast cancer risk. Genetic predisposition to obesity and to specific body fat distributions are also implicated. With obesity, there are increased levels of fat tissue that can store toxins and can serve as a continuous source of carcinogens. Recommendations for future research on anthropometric factors and breast cancer are provided. Sufficient evidence exists to support strategies to avoid weight gain throughout life as a means of reducing postmenopausal breast cancer risk.     

Factors associated with perceived risk of breast cancer among women attending a screening program

Summary A person's perception of the risk of, or susceptibility to, developing a disease is believed to be an important determinant of health-related behavior, yet little is known about the determinants of perceived risk. Knowledge of these correlates may be useful in identifying and addressing barriers to performance of health behaviors such as mammography screening. Data collected from over 36,000 women participating in a breast cancer screening program in Texas were used to examine the associations between perceived risk of ever getting breast cancer and a number of demographic factors, health-related behaviors, and risk factors for breast cancer. There was a strong positive association between family history of breast cancer and risk perception (OR=11.3, CI=10.34–12.35). Women who reported other risk factors for breast cancer also reported higher perceived risk, but those associations were of lesser magnitude. Age was inversely associated with perceived risk, and black, but not Hispanic, women were more likely to perceive their risk as high compared with white women. Of the health-related behaviors for the early detection of breast cancer, only having had a prior mammogram was associated with perceived risk. Educational interventions to heighten women's awareness of breast cancer risk factors may increase perceived risk in high risk women and influence their decision to undergo screening mammography.     

Equol,Adiponectin, Insulin Levels and Risk of Breast Cancer

Breast cancer is one of the most frequently diagnosed cancers and the leading cause of cancer death among women. Soy isoflavones have been widely studied and among all isoflavones equol has been gaining interest with regard to its relationship with breast cancer risk. Obesity has been revealed as one of the breast cancer risk factors, known to be associated with high levels of circulating insulin and decreased levels of adiponectin. Hence there have been many studies investigating relationships between insulin and adiponectin levels and breast cancer risk. Additionally recent findings have suggested that insulin and adiponectin themselves may have influence on breast cancer development, independent of obesity. In the present review, we discuss the relationships between breast cancer risk and equol, insulin and adiponectin levels, which are three important factors in our ongoing hospital-based case-control study. Herein these factors are reviewed not only from the clinical viewpoint but also from possible chemical and biological points of view which may explain clinical observations.     

Association of Family History and Other risk factors with Breast Cancer Risk among Japanese Premenopausal and Postmenopausal Women

Objectives: To determine the impact of family history (FH) on anthropometric and reproductive risk factors for breast cancer, a case-referent study was conducted using data from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan. Methods: In total, 1584 breast cancer cases were included and 15,331 women, confirmed as free of cancer, were recruited as the referents. Odds ratios and 95% confidence intervals were determined by logistic regression analysis. Separate analyses were performed for premenopausal and postmenopausal women. Results: Height, weight, and current body mass index (BMI) were positively associated with postmenopausal breast cancer regardless of FH, while these anthropometric factors did not alter risk in premenopausal women. The impacts of height and weight on postmenopausal breast cancer were more pronounced among FH women. There was little association with reproductive risk factors for premenopausal or postmenopausal breast cancer in FH cases, in clear contrast to the non-FH cases. Conclusions: These findings suggest some differences in risk impact of common etiologic factors between familial breast cancer and sporadic cases that may give pointers to further analysis of host-specific factors. They imply that avoidance of obesity after menopause may reduce the risk of breast cancer, regardless of FH.     

Genes implicated in hereditary breast cancer syndromes

The medical histories of breast cancer-prone families have been described for over a century. The pattern of breast cancer occurrences in these families is most consistent with an autosomal dominant mode of inheritance. The location of a gene that could explain the pattern of transmission of the breast cancer trait in families averaging early (pre-menopausal) onset of breast cancer was reported in 1990. Since then, two genes have been identified: BRCA1 and BRCA2. Germ-line mutations in these two genes confer susceptibility to breast (female and male) and ovarian cancer, and account for a significant proportion of hereditary breast cancer in two cancer syndromes: site-specific breast cancer and the breast-ovarian cancer syndrome. Other hereditary syndromes that feature breast cancer are Li-Fraumeni syndrome, Cowden disease, and ataxia telangiectasia, whose carriers have been shown to harbor germ-line mutations in TP53, PTEN, and ATM, respectively. There may be other genetic factors that contribute to hereditary breast cancer, since not all families with multiple cases of breast cancer harbor germ-line BRCA1 or BRCA2 mutations. Host factors (such as lifestyle choices) and other genes may modulate risk of breast cancer in mutation carriers.     

Risk factors for breast cancer in East Asian women relative to women in the West

The incidence of breast cancer in women of East Asian ancestry (Chinese, Japanese and Korean) is lower than in women of European ancestry but is currently rising. This review explores potential reasons for this inter‐ethnic difference in incidence by profiling breast cancer risk factors reported for East Asian and Western women. Factors such as endogenous hormone exposure, lifestyle choices, diet and genetic predisposition are associated with breast cancer risk in both East Asian and Western women. However, the relative exposure to these risk factors may vary according to a woman's geographical ancestry and culture. For example, age at menarche and menopause, parity, breast‐feeding history, low fat and high soy consumption as well as the prevalence of high risk genetic alleles may vary with a woman's geographical ancestry and/or culture. Differences in exposure to these risk factors in East Asian and Western women are consistent with the inter‐ethnic differences in breast cancer incidence observed. Understanding the underlying factors contributing to differences in the profile of breast cancer across populations is important when considering screening and prevention programs for East Asian women resident in the East or the West.     

Risk factors for breast cancer in East Asian women relative to women in the West

The incidence of breast cancer in women of East Asian ancestry (Chinese, Japanese and Korean) is lower than in women of European ancestry but is currently rising. This review explores potential reasons for this inter-ethnic difference in incidence by profiling breast cancer risk factors reported for East Asian and Western women. Factors such as endogenous hormone exposure, lifestyle choices, diet and genetic predisposition are associated with breast cancer risk in both East Asian and Western women. However, the relative exposure to these risk factors may vary according to a woman's geographical ancestry and culture. For example, age at menarche and menopause, parity, breast-feeding history, low fat and high soy consumption as well as the prevalence of high risk genetic alleles may vary with a woman's geographical ancestry and/or culture. Differences in exposure to these risk factors in East Asian and Western women are consistent with the inter-ethnic differences in breast cancer incidence observed. Understanding the underlying factors contributing to differences in the profile of breast cancer across populations is important when considering screening and prevention programs for East Asian women resident in the East or the West.