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BACKGROUND: In 2015, the second cycle of the CONCORD programme established global surveillance of cancer survival as a metric of the effectiveness of health systems and to inform global policy on cancer control. CONCORD-3 updates the worldwide surveillance of cancer survival to 2014. METHODS: CONCORD-3 includes individual records for 37·5 million patients diagnosed with cancer during the 15-year period 2000-14. Data were provided by 322 population-based cancer registries in 71 countries and territories, 47 of which provided data with 100% population coverage. The study includes 18 cancers or groups of cancers: oesophagus, stomach, colon, rectum, liver, pancreas, lung, breast (women), cervix, ovary, prostate, and melanoma of the skin in adults, and brain tumours, leukaemias, and lymphomas in both adults and children. Standardised quality control procedures were applied; errors were rectified by the registry concerned. We estimated 5-year net survival. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: For most cancers, 5-year net survival remains among the highest in the world in the USA and Canada, in Australia and New Zealand, and in Finland, Iceland, Norway, and Sweden. For many cancers, Denmark is closing the survival gap with the other Nordic countries. Survival trends are generally increasing, even for some of the more lethal cancers: in some countries, survival has increased by up to 5% for cancers of the liver, pancreas, and lung. For women diagnosed during 2010-14, 5-year survival for breast cancer is now 89·5% in Australia and 90·2% in the USA, but international differences remain very wide, with levels as low as 66·1% in India. For gastrointestinal cancers, the highest levels of 5-year survival are seen in southeast Asia: in South Korea for cancers of the stomach (68·9%), colon (71·8%), and rectum (71·1%); in Japan for oesophageal cancer (36·0%); and in Taiwan for liver cancer (27·9%). By contrast, in the same world region, survival is generally lower than elsewhere for melanoma of the skin (59·9% in South Korea, 52·1% in Taiwan, and 49·6% in China), and for both lymphoid malignancies (52·5%, 50·5%, and 38·3%) and myeloid malignancies (45·9%, 33·4%, and 24·8%). For children diagnosed during 2010-14, 5-year survival for acute lymphoblastic leukaemia ranged from 49·8% in Ecuador to 95·2% in Finland. 5-year survival from brain tumours in children is higher than for adults but the global range is very wide (from 28·9% in Brazil to nearly 80% in Sweden and Denmark). INTERPRETATION: The CONCORD programme enables timely comparisons of the overall effectiveness of health systems in providing care for 18 cancers that collectively represent 75% of all cancers diagnosed worldwide every year. It contributes to the evidence base for global policy on cancer control. Since 2017, the Organisation for Economic Co-operation and Development has used findings from the CONCORD programme as the official benchmark of cancer survival, among their indicators of the quality of health care in 48 countries worldwide. Governments must recognise population-based cancer registries as key policy tools that can be used to evaluate both the impact of cancer prevention strategies and the effectiveness of health systems for all patients diagnosed with cancer. FUNDING: American Cancer Society; Centers for Disease Control and Prevention; Swiss Re; Swiss Cancer Research foundation; Swiss Cancer League; Institut National du Cancer; La Ligue Contre le Cancer; Rossy Family Foundation; US National Cancer Institute; and the Susan G Komen Foundation.
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Neoplasias/mortalidade , Humanos , Neoplasias/patologia , Vigilância da População , Sistema de Registros , Taxa de SobrevidaRESUMO
BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems. FUNDING: Canadian Partnership Against Cancer (Toronto, Canada), Cancer Focus Northern Ireland (Belfast, UK), Cancer Institute New South Wales (Sydney, Australia), Cancer Research UK (London, UK), Centers for Disease Control and Prevention (Atlanta, GA, USA), Swiss Re (London, UK), Swiss Cancer Research foundation (Bern, Switzerland), Swiss Cancer League (Bern, Switzerland), and University of Kentucky (Lexington, KY, USA).
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Neoplasias/mortalidade , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Saúde Global , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Distribuição por Sexo , Análise de Sobrevida , Adulto JovemRESUMO
BACKGROUND: Men of African descent have the highest incidence and mortality rates of prostate cancer (PrCa) worldwide. Notably, PrCa is increasing in Africa with Nigerian men being mostly affected. Thus, it is important to understand risk factors for PrCa in Nigeria and build capacity for cancer research. The goals of this study were to determine the feasibility of conducting an epidemiological study of PrCa and to obtain preliminary data on risk factors for PrCa in Nigeria. METHODS: A case-control study (50 cases/50 controls) was conducted at the University College Hospital (UCH) in Ibadan, Nigeria, between October 2011 and December 2012. Men aged 40 to 80 years were approached for the study and asked to provide informed consent and complete the research protocol. Logistic regression models were used to examine associations between demographic, social and lifestyle characteristics and risk of PrCa. RESULTS: The participation rate among cases and controls was 98% and 93%, respectively. All participants completed a questionnaire and 99% (50 cases/49 controls) provided blood samples. Cases had a median serum diagnostic PSA of 73 ng/ml, and 38% had a Gleason score 8-10 tumor. Family history of PrCa was associated with a 4.9-fold increased risk of PrCa (95% CI 1.0 - 24.8). There were statistically significant inverse associations between PrCa and height, weight and waist circumference, but there was no association with body mass index (kg/m(2)). There were no associations between other socio-demographic and lifestyle characteristics and PrCa risk. CONCLUSION: This feasibility study demonstrated the ability to ascertain and recruit participants at UCH and collect epidemiological, clinical and biospecimen data. Our results highlighted the advanced clinical characteristics of PrCa in Nigerian men, and that family history of PrCa and some anthropometric factors were associated with PrCa risk in this population. However, larger studies are needed to better understand the epidemiological risk factors of PrCa in Nigeria.
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Neoplasias da Próstata/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Pesos e Medidas Corporais , Estudos de Casos e Controles , Estudos de Viabilidade , Predisposição Genética para Doença , Humanos , Incidência , Estilo de Vida , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Nigéria/epidemiologia , Antígeno Prostático Específico , Fatores de Risco , Fatores SocioeconômicosRESUMO
The low overall survival rates of patients with breast cancer in sub-Saharan Africa (SSA) are driven by regionally differing tumor biology, advanced tumor stages at diagnosis, and limited access to therapy. However, it is not known whether regional differences in the composition of the tumor microenvironment (TME) exist and affect patients' prognosis. In this international, multicentre cohort study, 1,237 formalin-fixed, paraffin-embedded breast cancer samples, including samples of the "African Breast Cancer-Disparities in Outcomes (ABC-DO) Study," were analyzed. The immune cell phenotypes, their spatial distribution in the TME, and immune escape mechanisms of breast cancer samples from SSA and Germany (n = 117) were investigated using histomorphology, conventional and multiplex IHC, and RNA expression analysis. The data revealed no regional differences in the number of tumor-infiltrating lymphocytes (TIL) in the 1,237 SSA breast cancer samples, while the distribution of TILs in different breast cancer IHC subtypes showed regional diversity, particularly when compared with German samples. Higher TIL densities were associated with better survival in the SSA cohort (n = 400), but regional differences concerning the predictive value of TILs existed. High numbers of CD163+ macrophages and CD3+CD8+ T cells accompanied by reduced cytotoxicity, altered IL10 and IFNγ levels and downregulation of MHC class I components were predominantly detected in breast cancer samples from Western SSA. Features of nonimmunogenic breast cancer phenotypes were associated with reduced patient survival (n = 131). We therefore conclude that regional diversity in the distribution of breast cancer subtypes, TME composition, and immune escape mechanisms should be considered for therapy decisions in SSA and the design of personalized therapies. See related Spotlight by Bergin et al., p. 705.
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Neoplasias , Microambiente Tumoral , Prognóstico , Estudos de Coortes , Linfócitos do Interstício Tumoral , Macrófagos , Neoplasias/patologiaRESUMO
Background: We recently developed a multi-ancestry polygenic risk score (PRS) that effectively stratifies prostate cancer risk across populations. In this study, we validated the performance of the PRS in the multi-ancestry Million Veteran Program and additional independent studies. Methods: Within each ancestry population, the association of PRS with prostate cancer risk was evaluated separately in each case-control study and then combined in a fixed-effects inverse-variance-weighted meta-analysis. We further assessed the effect modification by age and estimated the age-specific absolute risk of prostate cancer for each ancestry population. Results: The PRS was evaluated in 31,925 cases and 490,507 controls, including men from European (22,049 cases, 414,249 controls), African (8794 cases, 55,657 controls), and Hispanic (1082 cases, 20,601 controls) populations. Comparing men in the top decile (90-100% of the PRS) to the average 40-60% PRS category, the prostate cancer odds ratio (OR) was 3.8-fold in European ancestry men (95% CI = 3.62-3.96), 2.8-fold in African ancestry men (95% CI = 2.59-3.03), and 3.2-fold in Hispanic men (95% CI = 2.64-3.92). The PRS did not discriminate risk of aggressive versus nonaggressive prostate cancer. However, the OR diminished with advancing age (European ancestry men in the top decile: ≤55 years, OR = 7.11; 55-60 years, OR = 4.26; >70 years, OR = 2.79). Men in the top PRS decile reached 5% absolute prostate cancer risk ~10 years younger than men in the 40-60% PRS category. Conclusions: Our findings validate the multi-ancestry PRS as an effective prostate cancer risk stratification tool across populations. A clinical study of PRS is warranted to determine whether the PRS could be used for risk-stratified screening and early detection. Funding: This work was supported by the National Cancer Institute at the National Institutes of Health (grant numbers U19 CA214253 to C.A.H., U01 CA257328 to C.A.H., U19 CA148537 to C.A.H., R01 CA165862 to C.A.H., K99 CA246063 to B.F.D, and T32CA229110 to F.C), the Prostate Cancer Foundation (grants 21YOUN11 to B.F.D. and 20CHAS03 to C.A.H.), the Achievement Rewards for College Scientists Foundation Los Angeles Founder Chapter to B.F.D, and the Million Veteran Program-MVP017. This research has been conducted using the UK Biobank Resource under application number 42195. This research is based on data from the Million Veteran Program, Office of Research and Development, and the Veterans Health Administration. This publication does not represent the views of the Department of Veteran Affairs or the United States Government.
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Estudo de Associação Genômica Ampla , Neoplasias da Próstata , Fatores Etários , Estudos de Casos e Controles , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Herança Multifatorial , Neoplasias da Próstata/epidemiologia , Neoplasias da Próstata/genética , Fatores de Risco , Estados Unidos/epidemiologiaRESUMO
BACKGROUND: Prostate cancer is the leading cancer in men in sub-Saharan Africa (SSA) regarding incidence and mortality. Published data from a few registries in SSA suggest that the rates are still rising, but there is little comprehensive information on the time trends of prostate cancer incidence. METHODS: We analyzed registry data on 13,170 incident prostate cancer cases in men aged 40 years or above, from 12 population-based cancer registries in 11 SSA countries, with at least a 10-year time span of comparable data. RESULTS: We observed an increase in cumulative risks (CR) and age-standardized incidence rates (ASR) over time in all registries (statistically significant in all but one). The highest values of CR were found in Seychelles and Harare (Zimbabwe). The highest annual increase in the ASRs was seen in Seychelles and Eastern Cape (South Africa), whereas the lowest was seen in Mauritius. We mainly found a steady increase in incidence with age and during successive periods. CONCLUSIONS: This analysis reveals that prostate cancer incidence rates are rising in many populations in SSA-often very rapidly-which is in contrast to recent observations worldwide. We acknowledge that the reasons are multifactorial and largely remain unclear, but believe that they are primarily associated with improvements in health care systems, for example, a broader use of prostate-specific antigen testing. IMPACT: This study is the first to compare population-level data on time trends of prostate cancer incidence between multiple countries of SSA, presenting the different rates of increase in 11 of them.
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Neoplasias da Próstata/epidemiologia , África Subsaariana , Distribuição por Idade , Humanos , Masculino , Vigilância da População , Sistema de Registros , Fatores de RiscoRESUMO
The original version of this article unfortunately contained a mistake. In Table 2, the number 36 under "N" should be 96 and "Tumour size in cm (range)" should read "Tumour size in cm."
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PURPOSE: To determine the pattern and significance of tumour budding among colorectal carcinoma (CRC) Nigerian patients using the 2016 International Tumour Budding Consensus Conference (ITBCC) guidelines. METHODS: H&E-stained slides of resected CRC at the University College Hospital and a private laboratory, both in Ibadan, Nigeria, from January 2008 to December 2017 were reviewed. Patient age, gender, tumour size and location were obtained from the surgical pathology records. Tumours were graded and staged according to the 2010 WHO and the 2017 UICC protocols, respectively. Tumour budding was determined at × 20 objective lens magnification with a 20-mm eyepiece field number diameter. Descriptive, Mann-Whitney U and chi-square test statistics were applied using SPSS 20; p < 0.05 was considered significant. RESULTS: Ninety-six cases were included in this study. Fifty-one (53.1%) showed tumour budding. Tumour bud count was low (0-4) in 66 (68.8%), intermediate (5-9) in 12 (12.5%) and high (≥ 10) in 18 (18.8%) tumours. Four tumours had pT1 stage, 35 pT2, 37 pT3 and 20 pT4. Forty-three (44.8%) tumours were lymph node-positive, and 10 (10.4%) had metastasis. Patients' age and tumour size distribution were similar in the tumour budding and non-budding groups (52.4 ± 17.1/58.5 ± 13.9 years and 6.6 ± 2.9/6.6 ± 2.8 cm, respectively). There was significant association between tumour budding and tumour grade (p < 0.008), pT stage (p < 0.000), lymphovascular permeation (p < 0.000), perineural invasion (p < 0.003) and nodal status (p < 0.034), but not with gender (p = 0.588), metastasis (p = 0.327) and TNM group-stage (p = 0.062). CONCLUSION: Tumour budding frequency is high among our CRC patients and is associated with poorer prognostic factors.
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Adenocarcinoma Mucinoso/patologia , Neoplasias Colorretais/patologia , Guias de Prática Clínica como Assunto/normas , Adenocarcinoma Mucinoso/economia , Adenocarcinoma Mucinoso/cirurgia , Neoplasias Colorretais/economia , Neoplasias Colorretais/cirurgia , Países em Desenvolvimento , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Nigéria , Estudos RetrospectivosRESUMO
BACKGROUND: Colorectal cancer (CRC) is the fifth most common cancer in Africa, with significant differences in incidence, biology and clinical behavior from other populations. MATERIALS AND METHODS: We studied prevalence and clinicopathological features of microsatellite instability (MSI) and young onset CRC in 83 archival samples from the University of Ibadan, Nigeria. RESULTS: Nigerian cases of CRC were MSI-high in 43% and MSI-high CRC had significantly lower histological heterogeneity than microsatellite-stable CRC (20% vs. 55% respectively, p=0.046). Presence of signet ring cell differentiation (10-50% of tumor) was significantly higher in younger patients with CRC (<50 years) (odds ratio(OR)=5.93, 95% confidence interval(CI)=1.17-29.95, p=0.038). Poor differentiation (34%), invasive growth (96%), and high prevalence of mucinous (10%) and signet ring cell adenocarcinomas (4%) were among distinct features of Nigerian patients with CRC. CONCLUSION: MSI-high CRC is more common in West Africa and more detailed molecular and genetic analysis is warranted as CRC incidence and mortality continue to increase in the Sub-Saharan Africa.
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Adenocarcinoma Mucinoso/genética , População Negra/genética , Carcinoma de Células em Anel de Sinete/genética , Neoplasias Colorretais/genética , Instabilidade de Microssatélites , Adenocarcinoma Mucinoso/epidemiologia , Adenocarcinoma Mucinoso/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células em Anel de Sinete/epidemiologia , Carcinoma de Células em Anel de Sinete/patologia , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Nigéria/epidemiologia , Razão de Chances , Prevalência , Adulto JovemRESUMO
UNLABELLED: Prostate cancer is the second most frequently diagnosed cancer of men (913 000 new cases, 13.8% of the total) and the fifth most common cancer overall. Prostate cancer is the sixth leading cause of death from cancer in men (6.1% of the total).The incidence of prostate cancer in Nigerian men is believed to be on the increase and it had become the number one cancer in 1999, constituting 11% of all male cancers in the population served by the Ibadan cancer Registry. Studies from Ibadan and from other sites in Nigeria (Benin, Calabar, Kano, Lagos, Maiduguri, and Zaria) have shown an increasing incidence of prostate cancer accounting for anything between 6 and 12 % of total cancers in these centres and up to about 18% of prostatic neoplasms in some. Most patients present in late stage disease, and the mortality is high.It is uncertain whether there is a biophysical component to the increased incidence of prostate cancer in Nigerian and other West African men although a few studies point in this direction.It appears there is inadequate information regarding the incidence and mortality of prostate cancer, and that health care professionals do not routinely provide information regarding the importance of screening for prostate cancer before age 50 for high-risk populations.The Revised National health Policy for Nigeria (Sept 2004) has as its long term goal 'to provide the entire population with adequate access, not only to primary health care but also to secondary and tertiary services through a well functioning referral system' and also "Ensuring equitable distribution of human resources for healthcare delivery between urban and rural areas, including difficult terrain, such as mountainous, riverine and inaccessible areas of the country."At the moment however, Public expenditure on health is less than $8 per capita, compared to the $34 recommended internationally. Private expenditures are estimated to be over 70% of total health expenditure, most of this from out-of-pocket. Yet there is endemic poverty. The National Health Insurance scheme (NHIS) is presently severely limited in its allowances and certainly so for cancer care. CONCLUSIONS: The following recommendations are therefore made:* Establishment of community outreaches for education and screening.* Improved completeness of records to understand the real burden of disease and funding studies to explore biophysical components that may be important in racial differences for this disease.* Increased access by increasing numbers of specialists required for clinical assessment and management.* Increase laboratory diagnostic support* Improved availability of drugs for the treatment of prostate cancer cases.
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BACKGROUND: The relationship between circulating levels of angiotensinogen and hypertension in the epidemiologic setting has not been studied much. Recent findings related to the association between hypertension and polymorphisms of the angiotensinogen gene have generated new interest in this potential pathway to hypertension. OBJECTIVES: To examine environmental factors associated with levels of circulating angiotensinogen as determinants of hypertension in populations of African origin. METHODS: We recruited 1557 participants from communities in Nigeria (n = 611), Zimbabwe (n = 161), Jamaica (n = 476), and Maywood, Illinois, USA (n = 309). RESULTS: Mean angiotensinogen levels varied widely across groups (Nigeria 1381 ng/ml angiotensin I generated, Zimbabwe 1638 ng/ml angiotensin and I generated Jamaica 1801 ng/ml angiotensin I generated, and Maywood 2039 ng/ml angiotensin I generated). Average body mass index was highly correlated to angiotensinogen level across the population samples, accounting for 90 percent of the between-sample variation. At the individual level the correlation between body mass index and angiotensinogen level was substantially smaller, in the range 0.04-0.15, although the association attained statistical significance for all but one of the populations. Women had higher levels of angiotensinogen and mean levels in subjects of both sexes declined in late middle age. Hypertensives also had significantly higher levels of angiotensinogen and we noted correlations to blood pressure for two of the four populations. CONCLUSIONS: Obesity, sex and age would all appear to be important modifiers of circulating angiotensinogen levels. The variation in level across populations was substantially larger than that which has been found previously in association with known genetic polymorphisms within populations, suggesting the possibility that environmental effects are more important than had previously been recognised.(AU)
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Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Angiotensinogênio/sangue , Obesidade/sangue , Obesidade/etnologia , Fatores Etários , Illinois , Jamaica , Nigéria , Fatores Sexuais , Zimbábue , Obesidade/fisiopatologiaRESUMO
Within the context of an international collaborative study of the evolution of hypertension in the black disapora, we determined the allelic distribution of hypertension candidate genes for the renin-angiotensin system in three populations of African origin. The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) and the M235T and T174M variants of the angiotensinogen (AGT) gene were examined in individuals from Nigeria, Jamaica, and the United States. Large differences in the prevalence of hypertension were recorded in door-to-door surveys, ranging from 16 percent in Nigeria to 33 percent in the United States. The frequency of the D allele was similar in all groups (54 percent, 59 percent and 63 percent in Nigeria, Jamaica, and the United States, respectively). The 235T allele of the AGT gene was found in 81 percent of US and Jamaican blacks and 91 percent of Nigerians: very little variation was seen for the T174M marker. Despite larger differences in hypertension rates, genetic variation at the index loci among these groups was modest. Overall, the frequency of the ACE D allele was only slightly higher than that reported for European and Japanese populations, whereas the AGT 235T allele was twice as common. Compared with blacks in the western hemisphere. Nigerians had a higher frequency of the 235T allele, which is consistent with 25 percent European admixture in Jamaica and the United States. The results indicate the potential for etiolgic heterogeneity in genetic factors related to hypertension across the ethnic groups while suggested that environmental exposures most likely explain the gradient in risk in the comparison among black populations.(AU)
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Angiotensinogênio/genética , Hipertensão/genética , Peptidil Dipeptidase A/genética , Alelos , Negro ou Afro-Americano , Hipertensão/etnologia , Jamaica/etnologia , Nigéria/etnologia , Polimorfismo Genético , Estados Unidos/etnologiaRESUMO
The role of leptin in humans remains controversial. Leptin concentrations are highly correlated with body fat stores. We tested whether or not this relation was consistent across the range of body composition encompassing the lean as well as the obese. Individuals participating in community-based comparative research in Nigeria (n = 363), Jamaica (n = 372), and the United States (Maywood, IL; n = 699) had their plasma leptin concentrations and body compositions (with bioelectrical impedance analysis) measured. All participants identified themselves as being black. Body mass index (in KG/m2) ranged from across populations for both men and women in Nigeria, Jamaica, and the United States, respectively (men: 2.8, 3.9, and 6.8 microg/L; women: 10.3, 18.6, and 27.7 microg/L). An exponential function fit the relation between percentage body fat or total fat mass and leptin for men and women at each site. For women and men the exponential function with either percentage body fat or total fat mass was of the same shape, but increased by a constant in women, yielding higher leptin concentrations than in men at every level of body fat. On the basis of this broad distribution of body composition, the data suggest an exponential response of leptin to increase in body fat stores, consistent with the development of leptin resistance in individuals developing obesity. These findings likewise confirm that men and women exhibit different set points in terms of leptin production(AU)
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Adulto , Estudo Comparativo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas/metabolismo , Composição Corporal , Tecido Adiposo , Jamaica/etnologia , Nigéria/etnologia , Estados Unidos/etnologiaRESUMO
Body mass index (BMI) is the most commonly used measure of obesity. Recently, some investigators have advocated direct measurement of adiposity rather than use of the BMI. This study was undertaken to determine the ability of BMI to predict body fat levels in three populations of West Africa heritage living in different environments. A total of 1,054 black men and women were examined in Nigeria, Jamaica, and the United States during 1994 and 1995. A standardized protocol was used to measure height, weight, waist and hip circumferences, and blood pressure at all sites; percentage of body fat was estimated using bioelectrical impedance analysis. Percentage of body fat and BMI were highly correlated within site- and sex-specific groups, and the resulting r2 ranged from 0.61 to 0.85. The relation was quadratic in all groups except Nigerian men, in whom it was linear. The regression coefficients were similar across sites, yet the mean body fat levels differed significantly (p < 0.001) as estimated by the intercept, making intersite comparison difficult. Compared with BMI, percentage of body fat was not a better predictor of blood pressure or waist or hip circumference.(AU)