Risk factors for breast cancer in a black population--the Barbados National Cancer Study

Reproductive Risk Factor Patterns in Caribbean Women With Breast Cancer Across 4 Generations

Importance

Breast cancer (BC) is commonly diagnosed among Caribbean women. Shifts in reproductive patterns modify the incidence of BC diagnosis and age at BC diagnosis in population-based studies; however, reproductive patterns in Caribbean women remain understudied.

Objective

To describe the temporal trends in reproductive patterns and age at BC diagnosis in Caribbean-born women.

Design, Setting, and Participants

A cross-sectional observational study-the Caribbean Women's Cancer Study-was conducted, with data on reproductive patterns known to affect BC risk collected in The Bahamas, Barbados, Cayman Islands, Dominica, Haiti, Jamaica, and Trinidad and Tobago. Participants were recruited prospectively. The sample included women born in Caribbean countries and diagnosed with invasive BC and/or ovarian cancer from June 1, 2010, to June 30, 2018, and was divided into 4 birth cohorts (born before 1950, 1950-1959, 1960-1969, and in or after 1970). Data were analyzed between August 1, 2023, and July 31, 2024.

Exposures

Receipt of a BC diagnosis and birth in a Caribbean country.

Main Outcomes and Measures

Change in reproductive patterns between birth cohorts, including age at BC diagnosis, family history of cancer, age at first pregnancy, number of pregnancies, number of full-term pregnancies, number of siblings, age at menarche and menopause, estrogen receptor status, and germline pathogenic/likely pathogenic variants.

Results

Of 1015 participants diagnosed with BC and ovarian cancer, 995 women (mean [SD] age, 46.6 [10.8] years; 605 [81.8%] Afro-Caribbean, 98 [13.2%] East Indian, 22 [3.0%] White, and 12 [1.6%] >1 race) received a diagnosis of invasive BC. Comparison from older to younger birth cohorts (presented in the order of born before 1950, 1950-1959, 1960-1969 and in or after 1970) showed an increased proportion of women experiencing menarche at age 12 years or younger (33.0% vs 47.3% vs 45.5% vs 57.9%; P < .001), women with no pregnancies (6.8% vs 6.8% vs 10.5% vs 22.8%; P < .001), and nulliparous women (8.6% vs 9.2% vs 13.9% vs 27.6%; P < .001). Younger age at BC diagnosis was observed in women experiencing menarche at age 12 years or younger (mean [SD], 45.0 [10.5] years) vs 15 years or older (mean [SD], 49.1 [11.2] years) and in nulliparous women (mean [SD], 42.1 [11.2] years) vs 3 or more full-term pregnancies (mean [SD], 49.9 [10.6] years; P < .001). For every year of first pregnancy delay, women had a 4% increased chance of being diagnosed with estrogen receptor-positive tumors (odds ratio, 1.04; 95% CI, 1.01-1.08; P = .02).

Conclusions and Relevance

In this cross-sectional study, between each 10-year birth cohort, women diagnosed with BC had a lower age at menarche, number of pregnancies, and number of full-term pregnancies. These findings suggest that interventions targeting other BC risk factors need to be implemented.

Reproductive factors and the risk of breast cancer among Nigerian women by age and oestrogen receptor status

PURPOSE OF THE STUDY

The aim of the study was to investigate the association between reproductive factors and breast cancer risk in Nigeria. This has not been widely investigated in sub-Saharan Africa.

METHODS

We conducted a hospital-based case-control study involving participants from five hospitals in Lagos and Abuja. Women were interviewed in-person between October 2016 and May 2017 using a semi-structured questionnaire. We collected data on parity, breastfeeding, age at first and last birth, age at menarche, oral contraceptive use and history of abortion. The data were analysed using multivariable logistic regression adjusting for relevant confounders.

RESULTS

Every additional 6 months of breastfeeding over a lifetime reduced breast cancer odds by: 7% (95% CI: 1%, 12%) in all women, 15% (95% CI: 5%, 24%) in women < 50 years, and 8% (95% CI: 0%, 12%, p for trend = 0.043) in oestrogen receptor negative (ER-) cases. Each additional 1-year delay before the first full-term pregnancy increased oestrogen receptor positive breast cancer odds by 9% (95% CI: 2%, 17%). Each additional 1-year delay before the last full-term pregnancy increased breast cancer odds by: 7% (95% CI: 2%, 12%) in all women, 12% (95% CI: 4%, 21%) in ER- breast cancer patients, and 14% (95% CI: 4%, 25%) in triple negative breast cancer patients. Other reproductive factors did not significantly increased breast cancer odds.

CONCLUSION

While advanced age at first and last full-term pregnancies increased breast cancer odds, breastfeeding reduced it. These associations varied by age and oestrogen receptor status. Improved breastfeeding practices and timely births should be promoted in Nigeria.

Breast Cancer in the Caribbean

Breast cancer (BC) is one of the leading causes of death among women globally. In the Caribbean, there is a higher mortality rate compared with North American and European countries which have higher incidence rates. We conducted a literature review to examine the BC dynamic in the Caribbean and determine the areas where further investigations are needed. The PubMed database was used for identifying relevant studies using a combination of specific keyword searches. All studies focusing on BC within the defined Caribbean population were selected for this review. A total of 117 papers were included. The data were organized and presented under the following headings and reported according to the country where available: BC incidence and mortality, patient demographics, clinicopathology, genetics, behavioral risks, diagnosis and treatment, and BC control. Our review uncovered major variability in the incidence, management, etiology, and mortality of BC among Caribbean countries. Low-resource countries are burdened by more advanced disease with expected poorer BC outcomes (i.e., shorter periods of disease-free survival). Countries with established national cancer registries seem to have a better approach to the management of BC. The introduction of cancer treatment programs in association with international nonprofit groups has shown tremendous improvement in quality, accessible cancer care for patients, particularly in low- and middle-income settings. BC research is relatively limited in the Caribbean, lacking in both scope and consistency. The unique Caribbean BC population of diverse ethnicities, environmental influence, immigrants, socioeconomic status, and sociocultural practices allows an optimal opportunity for epidemiological investigations that can provide deeper insights into the status of BC.

High triple-negative breast cancer prevalence and aggressive prognostic factors in Barbadian women with breast cancer

BACKGROUND

Women of African ancestry (WAA) are disproportionately affected by triple-negative breast cancer (TNBC), which remains one of the most clinically challenging breast cancer (BCa) subtypes. This study investigated the prevalence of TNBC and epidemiological trends for BCa in Barbados, a Caribbean island with a high percentage of African ancestry.

METHODS

Pathology reports for all BCa cases between 2007 and 2016 were collected from the sole hospital in Barbados and reviewed. The clinicopathological data collected included age, tumor grade, lymph node status, and hormone receptor status as determined by immunohistochemistry. BCa data for non-Hispanic white (NHW) and non-Hispanic black (NHB) American populations were accessed from the Surveillance, Epidemiology, and End Results database.

RESULTS

There were 1997 BCa cases in Barbados between 2007 and 2016 for an estimated incidence rate of 135.1 per 100,000 women in Barbados (standardized to the US population, where the standardized incidence rates for NHBs and NHWs were 141.4 and 152.6 per 100,000, respectively). Age-specific incidence rates in Barbados for this period were consistently higher in younger age groups (15-59 years) in comparison with NHWs and NHBs. Between 2010 and 2016 in Barbados, a TNBC prevalence of 25% was observed, whereas TNBC prevalences of 21% and 10% were observed in NHBs and NHWs, respectively.

CONCLUSIONS

The BCa incidence was higher in younger Barbadian women than NHWs and NHBs, and the TNBC prevalence was ~2.5 times higher than the prevalence in NHWs. This hints at a possible genetic predisposition and other socioeconomic factors that could explain the high TNBC prevalence and aggressive clinical course in WAA globally.

Stage at diagnosis and stage-specific survival of breast cancer in Latin America and the Caribbean: A systematic review and meta-analysis

BACKGROUND

Female breast cancer is the most common cancer in Latin American and Caribbean (LAC) countries and is the leading cause of cancer deaths. The high mortality-to-incidence ratio in the regions is associated with mainly the high proportion of advanced stage diagnosis, and also to inadequate access to health care. In this study we aimed to systematically review the proportion of advanced stage (III-IV) at diagnosis (pas) and the five-year stage-specific survival estimates of breast cancer in LAC countries.

METHODS

We searched MEDLINE, Embase, and LILACS (Latin American and Caribbean Health Science Literature) to identify studies, in any language, indexed before Nov 5, 2018. We also conducted manual search by reviewing citations of papers found. pas was summarized by random effects model meta-analysis, and meta-regression analysis to identify sources of variation. Stage-specific survival probabilities were described as provided by study authors, as it was not possible to conduct meta-analysis. PROSPERO CRD42017052493.

RESULTS

For pas we included 63 studies, 13 of which population-based, from 22 countries comprising 221,255 women diagnosed from 1966 to 2017. The distribution of patients by stage varied greatly in LAC (pas 40.8%, 95%CI 37.0% to 44.6%; I2 = 99%; p<0.0001). The heterogeneity was not explained by any variable included in the meta-regression. There was no difference in pas among the Caribbean (pas 43.0%, 95%CI 33.1% to 53.6%), Central America (pas 47.0%, 95%CI 40.4% to 53.8%) and South America (pas 37.7%, 95%CI 33.1% to 42.5%) regions. For 5-year stage-specific survival we included 37 studies, comprising 28,988 women from ten countries. Seven of these studies were included also for pas. Since we were unable to adjust for age, comparability between countries and regions was hampered, and as expected, the results varied widely from study to study.

CONCLUSIONS

LAC countries should look to address concerns with early detection and diagnosis of breast cancer, and wherever viable implement screening programs and to provide timely treatment.

Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry

Gene expression changes within the Hippo pathway were found to be associated with large tumor size and metastasis in breast cancer. The combined effect of genetic variants in genes of this pathway may have a causal role in breast cancer development. We examined 7086 SNPs that were not highly correlated (r2  < 0.8) in 35 Hippo pathway genes using data from the genome-wide association study of breast cancer from the Root Consortium, which includes 3686 participants of African ancestry from Nigeria, United States of America, and Barbados: 1657 cases (403 estrogen receptor-positive [ER+], 374 ER-) and 2029 controls. Gene-level analyses were conducted using improved AdaJoint test for large-scale genetic association studies adjusting for age, study site and the first four eigenvectors from the principal component analysis. SNP-level analyses were conducted with logistic regression. The Hippo pathway was significantly associated with risk of ER+ breast cancer (pathway-level P = 0.019), with WWC1 (Padj  = 0.04) being the leading gene. The pathway-level significance was lost without WWC1 (P = 0.12). rs147106204 in the WWC1 gene was the most statistically significant SNP after gene-level adjustment for multiple comparisons (OR = 0.53, 95%CI = 0.41-0.70, Padj  = 0.025). We found evidence of an association between genetic variations in the Hippo pathway and ER+ breast cancer. Moreover, WWC1 was identified as the most important genetic susceptibility locus highlighting the importance of genetic epidemiology studies of breast cancer in understudied populations.

Breast cancer screening in a resource poor country: Ultrasound versus mammography

BACKGROUND

Breast cancer is the commonest female cancer in Nigeria. Despite its increased awareness, affordability of available screening tools is a bane. Mammography, the goal standard for screening is costly and not widely available in terms of infrastructure, technical/personnel capabilities. Ultrasound is accessible and affordable.

OBJECTIVES

This study compared the use of ultrasound and mammography as breast cancer screening tools in women in South West Nigeria by characterizing and comparing the prevalent breast parenchyma, breast cancer features and the independent sensitivity of ultrasound and mammography.

METHODS

This cross sectional comparative descriptive study used both ultrasound and mammography as screening tools in 300 consenting women aged 30 to 60 years who attended a free breast cancer screening campaign in a tertiary hospital in Lagos. Categorical variables were presented in tables and Chi squares for associations P-value set at ± 0.1.

RESULTS

Mean age was 41.01 + 6.5years with majority in the 30 - 39 year age group 139 (55%). Fatty (BIRADS A and B) parenchyma predominated {ultrasound 237 (79%); mammography 233 (77.7%)} in all age groups. 7 (2.3%) were confirmed malignant by histology with (6) in the 30-39 age group and (1) in the 40-49 age group. Ultrasound detected all the confirmed cases 7(100%), whereas mammography detected 6 (85%). Sensitivity was higher using ultrasound (100%) than mammography (85.7%).

CONCLUSION

Ultrasound can be utilized as a first line of screening especially in remote/rural areas in developing world.

FUNDING

Part funding from Run for Cure governmental organization.

Non-communicable chronic diseases and timely breast cancer screening among women of the Eastern Caribbean Health Outcomes Research Network (ECHORN) Cohort Study

PURPOSE

The Caribbean population faces a growing burden of multiple non-communicable chronic diseases (NCDs). Breast cancer is the leading cause of cancer death for women in the Caribbean. Given the substantial burden of NCDs across the region, cancer prevention and control strategies may need to be specifically tailored for people with multiple co-morbidities. Preventive screening, such as timely mammography, is essential but may be either facilitated or hampered by chronic disease control. The main objective of this study is to examine the relationship between a chronic disease and timely breast cancer screening.

METHODS

We conducted a cross-sectional data analysis using baseline data from the Eastern Caribbean Health Outcomes Research Network (ECHORN) Cohort Study-ECS. Our independent variables were presence of chronic diseases (hypertension or diabetes), defined as having been told by a clinical provider. Our dependent variable was timely screening mammography, as defined by receipt of mammography within the past 2 years. We examined bivariate and multivariate associations of covariates and timely screening mammography.

RESULTS

In our sample (n = 841), 52% reported timely screening mammography. Among those with timely screening, 50.8% reported having hypertension, and 22.3% reported having diabetes. In our bivariate analyses, both diabetes and hypertension were associated with timely screening mammography. In partially adjusted models, we found that women with diabetes were significantly more likely to report timely screening mammography than women without diabetes. In our fully adjusted models, the association was no longer significant. Having a usual source of healthcare and a woman's island of residence were significantly associated with timely screening mammography (p < 0.05).

CONCLUSIONS

We found that half of eligible women received timely screening mammography. Diabetes and hypertension, though common, are not associated with timely screening mammography. Usual source of care remains an important factor to timely breast cancer screening.

Social determinants of breast cancer in the Caribbean: a systematic review

BACKGROUND

Breast cancer is the leading cause of cancer deaths among women in the Caribbean and accounts for >1 million disability adjusted life years. Little is known about the social inequalities of this disease in the Caribbean. In support of the Rio Political Declaration on addressing health inequities, this article presents a systematic review of evidence on the distribution, by social determinants, of breast cancer risk factors, frequency, and adverse outcomes in Caribbean women.

METHODS

MEDLINE, EMBASE, SciELO, CINAHL, CUMED, LILACS, and IBECS were searched for observational studies reporting associations between social determinants and breast cancer risk factors, frequency, or outcomes. Based on the PROGRESS-plus checklist, we considered 8 social determinant groups for 14 breast cancer endpoints, which totalled to 189 possible ways ('relationship groups') to explore the role of social determinants on breast cancer. Studies with >50 participants conducted in Caribbean territories between 2004 and 2014 were eligible for inclusion. The review was conducted according to STROBE and PRISMA guidelines and results were planned as a narrative synthesis, with meta-analysis if possible.

RESULTS

Thirty-four articles were included from 5,190 screened citations. From these included studies, 75 inequality relationships were reported examining 30 distinct relationship groups, leaving 84% of relationship groups unexplored. Most inequality relationships were reported for risk factors, particularly alcohol and overweight/obesity which generally showed a positive relationship with indicators of lower socioeconomic position. Evidence for breast cancer frequency and outcomes was scarce. Unmarried women tended to have a higher likelihood of being diagnosed with breast cancer when compared to married women. While no association was observed between breast cancer frequency and ethnicity, mortality from breast cancer was shown to be slightly higher among Asian-Indian compared to African-descent populations in Trinidad (OR 1.2, 95% CI 1.1-1.4) and Guyana (OR 1.3, 95% CI 1.0-1.6).

CONCLUSION

Study quantity, quality, and variability in outcomes and reporting limited the synthesis of evidence on the role of social determinants on breast cancer in the Caribbean. This report represents important current evidence on the region, and can guide future research priorities for better describing and understanding of Caribbean breast cancer inequalities.

Genetic variants in microRNA and microRNA biogenesis pathway genes and breast cancer risk among women of African ancestry

MicroRNAs (miRNA) regulate breast biology by binding to specific RNA sequences, leading to RNA degradation and inhibition of translation of their target genes. While germline genetic variations may disrupt some of these interactions between miRNAs and their targets, studies assessing the relationship between genetic variations in the miRNA network and breast cancer risk are still limited, particularly among women of African ancestry. We systematically put together a list of 822 and 10,468 genetic variants among primary miRNA sequences and 38 genes in the miRNA biogenesis pathway, respectively; and examined their association with breast cancer risk in the ROOT consortium which includes women of African ancestry. Findings were replicated in an independent consortium. Logistic regression was used to estimate the odds ratio (OR) and 95 % confidence intervals (CI). For overall breast cancer risk, three single-nucleotide polymorphisms (SNPs) in miRNA biogenesis genes DROSHA rs78393591 (OR = 0.69, 95 % CI: 0.55-0.88, P = 0.003), ESR1 rs523736 (OR = 0.88, 95 % CI: 0.82-0.95, P = 3.99 × 10(-4)), and ZCCHC11 rs114101502 (OR = 1.33, 95 % CI: 1.11-1.59, P = 0.002), and one SNP in primary miRNA sequence (rs116159732 in miR-6826, OR = 0.74, 95 % CI: 0.63-0.89, P = 0.001) were found to have significant associations in both discovery and validation phases. In a subgroup analysis, two SNPs were associated with risk of estrogen receptor (ER)-negative breast cancer, and three SNPs were associated with risk of ER-positive breast cancer. Several variants in miRNA and miRNA biogenesis pathway genes were associated with breast cancer risk. Risk associations varied by ER status, suggesting potential new mechanisms in etiology.

Does cancer risk increase with HbA1c, independent of diabetes?

Background:

The risks for several cancer types are increased in people with diabetes. Hyperglycaemia, hyperinsulinaemia, inflammation and altered hormonal concentrations are common characteristics between the two diseases and can all be linked to hyperglycaemia.

Methods:

Here, we use glycated haemoglobin (HbA_1c) as a biomarker for chronic hyperglycaemia. We explore whether cancer risk increases with HbA_1c, independent of diabetes, and, therefore, if risk is already increased below the diabetic HbA_1c range, by analysing data from current studies linking HbA_1c to risk of several cancer types.

Results:

The data reveal that chronic hyperglycaemia correlates with increased cancer risk for a number of cancers, except prostate cancer. Evidence is also provided that risk is already increased in the pre-diabetic and normal ranges for several cancers.

Conclusions:

These results merit urgent investigation into the risks and advantages of updating recommendations for stricter glycaemic control in diabetic and non-diabetic subjects, as this could help reduce the risk of cancer incidence and mortality.

Traditional dietary pattern of South America is linked to breast cancer: an ongoing case-control study in Argentina

INTRODUCTION

Several studies have shown the effect of dietary patterns on breast cancer risk, but none has been conducted in Argentina. The aim of this study was to extract dietary patterns from Food Frequency Questioner, to estimate their effect on breast cancer occurrence while taking into account aggregation factors (family history of breast cancer) and to explore the sensitivity of the estimates to changes in the assumptions.

METHODS

A principal component exploratory factor analysis was applied to identify dietary patterns, which were then included as covariates in a multilevel logistic regression. Family history of BC was considered as a clustering variable. A multiple probabilistic sensitivity analysis was also performed.

RESULTS

The study included 100 cases and 294 controls. Four dietary patterns were identified. Traditional (fat meats, bakery products, and vegetable oil and mayonnaise) (OR III tertile vs I 3.13, 95% CI 2.58-3.78), Rural (processed meat) (OR III tertile vs I 2.02, 95% CI 1.21-3.37) and Starchy (refined grains) (OR III tertile vs I 1.82, 95 % CI 1.18-2.79) dietary patterns were positively associated with BC risk, whereas the Prudent pattern (fruit and non-starchy vegetables) (OR III tertile vs I 0.56, 95% CI 0.41-0.77) showed a protective effect. For Traditional pattern, the median bias-adjusted ORs (3.52) were higher than the conventional (2.76).

CONCLUSIONS

While the Prudent pattern was associated with a reduced risk of BC, Traditional, Rural and Starchy patterns showed a promoting effect. Despite the threats to validity, the nature of associations was not strongly affected.

Risk factors of breast cancer: a systematic review and meta-analysis

The etiology of breast cancer might be explained by 2 mechanisms, namely, differentiation and proliferation of breast epithelial cells mediated by hormonal factors. We performed a systematic review and meta-analysis to update effects of risk factors for both mechanisms. MEDLINE and EMBASE were searched up to January 2011. Studies that assessed association between oral contraceptives (OC), hormonal replacement therapy (HRT), diabetes mellitus (DM), or breastfeeding and breast cancer were eligible. Relative risks with their confidence intervals (CIs) were extracted. A random-effects method was applied for pooling the effect size. The pooled odds ratios of OC, HRT, and DM were 1.10 (95% CI = 1.03-1.18), 1.23 (95% CI = 1.21-1.25), and 1.14 (95% CI = 1.09-1.19), respectively, whereas the pooled odds ratio of ever-breastfeeding was 0.72 (95% CI = 0.58-0.89). Our study suggests that OC, HRT, and DM might increase risks, whereas breastfeeding might lower risks of breast cancer.

Fine mapping of breast cancer genome-wide association studies loci in women of African ancestry identifies novel susceptibility markers

Numerous single nucleotide polymorphisms (SNPs) associated with breast cancer susceptibility have been identified by genome-wide association studies (GWAS). However, these SNPs were primarily discovered and validated in women of European and Asian ancestry. Because linkage disequilibrium is ancestry-dependent and heterogeneous among racial/ethnic populations, we evaluated common genetic variants at 22 GWAS-identified breast cancer susceptibility loci in a pooled sample of 1502 breast cancer cases and 1378 controls of African ancestry. None of the 22 GWAS index SNPs could be validated, challenging the direct generalizability of breast cancer risk variants identified in Caucasians or Asians to other populations. Novel breast cancer risk variants for women of African ancestry were identified in regions including 5p12 (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.11-1.76; P = 0.004), 5q11.2 (OR = 1.22, 95% CI = 1.09-1.36; P = 0.00053) and 10p15.1 (OR = 1.22, 95% CI = 1.08-1.38; P = 0.0015). We also found positive association signals in three regions (6q25.1, 10q26.13 and 16q12.1-q12.2) previously confirmed by fine mapping in women of African ancestry. In addition, polygenic model indicated that eight best markers in this study, compared with 22 GWAS-identified SNPs, could better predict breast cancer risk in women of African ancestry (per-allele OR = 1.21, 95% CI = 1.16-1.27; P = 9.7 × 10(-16)). Our results demonstrate that fine mapping is a powerful approach to better characterize the breast cancer risk alleles in diverse populations. Future studies and new GWAS in women of African ancestry hold promise to discover additional variants for breast cancer susceptibility with clinical implications throughout the African diaspora.

Recurrent BRCA1 and BRCA2 mutations in breast cancer patients of African ancestry

Recurrent mutations constituted nearly three quarters of all BRCA1 mutations and almost half of all BRCA2 mutations identified in the first cohort of the Nigerian Breast Cancer Study. To further characterize breast/ovarian cancer risks associated with BRCA1/BRCA2 mutations in the African diaspora, we genotyped recurrent mutations among Nigerian, African American, and Barbadian breast cancer patients. A replication cohort of 356 Nigerian breast cancer patients was genotyped for 12 recurrent BRCA1/2 mutant alleles (Y101X, 1742insG, 4241delTG, M1775R, 4359insC, C64Y, 1623delTTAAA, Q1090X, and 943ins10 from BRCA1, and 1538delAAGA, 2630del11, and 9045delGAAA from BRCA2) by means of SNaPshot followed by direct sequencing or by direct sequencing alone. In addition, 260 African Americans and 118 Barbadians were genotyped for six of the recurrent BRCA1 mutations by SNaPshot assay. Of all the BRCA1/2 recurrent mutations we identified in the first cohort, six were identified in 11 patients in the replication study. These mutation carriers constitute 3.1 % [95 % Confidence Interval (CI) 1.6-5.5 %] of the replication cohort. By comparison, 6.9 % (95 % CI 4.7-9.7 %) of the discovery cohort carried BRCA1/2 recurrent mutations. For the subset of recurrent mutations we tested in breast cancer cases from Barbados or the United States, only two 943ins10 carriers were identified in African Americans. Nigerian breast cancer patients from Ibadan carry a broad and unique spectrum of BRCA1/2 mutations. Our data suggest that BRCA1/2 mutation testing limited to recurrent mutations is not sufficient to understand the BRCA1/2-associated breast cancer risk in African populations in the diaspora. As the cost of Sanger sequencing is considerably reduced, deploying innovative technologies such as high throughput DNA sequencing of BRCA1/2 and other cancer susceptibility genes will be essential for identifying high-risk individuals and families to reduce the burden of aggressive early onset breast cancer in low-resource settings.

Body fat distribution and breast cancer risk: findings from the Nigerian breast cancer study

PURPOSE

The relationship between overall obesity and breast cancer risk has been well recognized, but the role of central obesity in breast cancer development is uncertain.

METHODS

Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 community controls were recruited into the Nigerian Breast Cancer Study at Ibadan, Nigeria. Logistic regressions were used to calculate multivariate odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, body mass index (BMI), and other known risk factors for breast cancer.

RESULTS

The OR for the highest quartile group of waist circumference relative to the lowest was 2.39 (95% CI, 1.59-3.60; P-trend < 0.001). Comparing women with waist/hip ratio (WHR) in the lowest quartile group, the OR for women in the highest quartile category was 2.15 (95% CI, 1.61-2.85; P-trend < 0.001). An inverse association was observed between hip circumference and breast cancer, with an OR of 0.36 for the highest quartile (95% CI, 0.24-0.55; P-trend < 0.001). The effects of these three measures existed in both pre- and postmenopausal women. Of note, we found a significant interaction between WHR and BMI (P-interaction = 0.016): the OR comparing the highest to the lowest WHR quartile was 2.81 (95% CI, 1.90-4.16) for women with BMI < 25 kg/m2 and 1.70 (95% CI, 1.11-2.61) for women with BMI ≥ 25 kg/m2.

CONCLUSIONS

These results suggest that central adiposity, measured by waist circumference and waist/hip ratio, was an important risk factor for breast cancer in Nigerian women, and the effect of central adiposity was strong in normal-weight women.

Evaluation of 19 susceptibility loci of breast cancer in women of African ancestry

Multiple breast cancer susceptibility loci have been identified in genome-wide association studies (GWAS) in populations of European and Asian ancestry using array chips optimized for populations of European ancestry. It is important to examine whether these loci are associated with breast cancer risk in women of African ancestry. We evaluated 25 single nucleotide polymorphisms (SNPs) at 19 loci in a pooled case-control study of breast cancer, which included 1509 cases and 1383 controls. Cases and controls were enrolled in Nigeria, Barbados and the USA; all women were of African ancestry. We found significant associations for three SNPs, which were in the same direction and of similar magnitude as those reported in previous fine-mapping studies in women of African ancestry. The allelic odds ratios were 1.24 [95% confidence interval (CI): 1.04-1.47; P = 0.018] for the rs2981578-G allele (10q26/FGFR2), 1.34 (95% CI: 1.10-1.63; P = 0.0035) for the rs9397435-G allele (6q25) and 1.12 (95% CI: 1.00-1.25; P = 0.04) for the rs3104793-C allele (16q12). Although a significant association was observed for an additional index SNP (rs3817198), it was in the opposite direction to prior GWAS studies. In conclusion, this study highlights the complexity of applying current GWAS findings across racial/ethnic groups, as none of GWAS-identified index SNPs could be replicated in women of African ancestry. Further fine-mapping studies in women of African ancestry will be needed to reveal additional and causal variants for breast cancer.

[Risk and protective factors for breast cancer: a systematic review]

This review aimed to investigate risk and protective factors for breast cancer and to analyze whether scientific evidence from the World Cancer Research Fund and American Institute for Cancer Research, published in 2007, was confirmed by new research. In May 2010 we reviewed cohort and case-control analytical studies from 2007 to 2010 in the PubMed, LILACS, and SciELO databases. We selected 27 articles (14 case-control and 13 cohort studies). Breastfeeding and physical activity were protective factors against breast cancer, and alcohol consumption was a risk factor. A direct proportional relationship was observed between larger waist circumference, weight throughout adulthood, and height and risk of breast cancer in postmenopausal women. The association between body fat and breast cancer is contradictory in both premenopausal and postmenopausal women. According to the accumulated evidence, breastfeeding and healthy lifestyle are the factors most strongly associated with breast cancer prevention.

Prostate cancer incidence and mortality in barbados, west indies

We describe prostate cancer incidence and mortality in Barbados, West Indies. We ascertained all histologically confirmed cases of prostate cancer during the period July 2002 to December 2008 and reviewed each death registration citing prostate cancer over a 14-year period commencing January 1995. There were 1101 new cases for an incidence rate of 160.4 (95% Confidence Interval: 151.0-170.2) per 100,000 standardized to the US population. Comparable rates in African-American and White American men were 248.2 (95% CI: 246.0-250.5) and 158.0 (95% CI: 157.5-158.6) per 100,000, respectively. Prostate cancer mortality rates in Barbados ranged from 63.2 to 101.6 per 100,000, compared to 51.1 to 78.8 per 100,000 among African Americans. Prostate cancer risks are lower in Caribbean-origin populations than previously believed, while mortality rates appeared to be higher than reported in African-American men. Studies in Caribbean populations may assist understanding of disparities among African-origin populations with shared heredity.

Body size and breast cancer in a black population--the Barbados National Cancer Study

OBJECTIVE

To evaluate the relationship between body size and incident breast cancer in an African-origin Caribbean population.

METHODS

This investigation is based on 222 incident breast cancer cases and 454 controls from the Barbados National Cancer Study (BNCS) in whom body size variables that included height, weight, body-mass index (BMI), waist and hip circumferences (WC, HC), and waist-hip ratio (WHR) were compared. Multivariate-adjusted logistic regression analyses were performed and the findings are presented as odds ratios (ORs) with 95% confidence intervals (CI).

RESULTS

Although 33% of cases and 39% of controls were obese (BMI > or = 30 kg/m(2)), BMI was not found to be a significant predictor of breast cancer in the multivariate analyses. Tall stature increased risk among women > or =50 years (OR = 2.16, 95% CI (1.02, 4.58)), and a dual effect with age was suggested for both WC and WHR (decreased risk for those aged < or =50 years; increased risk among those > or =50 years).

CONCLUSIONS

Body size appears to influence the risk of breast cancer in this population of African origin. The BNCS data suggest that a few, but not all body size factors play a role in breast cancer risk, and that age may affect these relationships.

Breast cancer incidence and mortality in a Caribbean population: comparisons with African-Americans

We describe breast cancer incidence and mortality in the predominantly African-origin population of Barbados, which shares an ancestral origin with African-Americans. Age-standardized incidence rates were calculated from histologically confirmed breast cancer cases identified during a 45-month period (July 2002-March 2006). Mortality rates were estimated from death registrations over 10-years starting January 1995. There were 396 incident cases of breast cancer for an incidence rate of 78.1 (95% confidence interval (CI) 70.5-86.3), standardized to the US population. Breast cancer incidence in African-Americans between 2000 and 2004 was 143.7 (142.0-145.5) per 100,000. Incidence peaked at 226.6 (174.5-289.4) per 100,000 among Barbadian women aged 50-54 years, and declined thereafter, a pattern in marked contrast to trends in African-American women, whose rates continued to increase to a peak of 483.5 per 100,000 in those aged 75-79 years. Incidence rate ratios comparing Barbadian and African-American women showed no statistically significant differences among women aged>or=55 years (p<or=0.001 at all older ages). The age-standardized mortality rate in Barbados was 32.9 (29.9-36.0) per 100,000; similar to reported US rates. The pattern of diverging breast cancer incidence between Barbadian and African-American women may suggest a greater contribution from genetic factors in younger women, and from environmental factors in older women. Studies in intermediate risk populations, such as Barbados, may assist the understanding of racial disparities in breast cancer.