Clinicopathological features and molecular markers of breast cancer in Jos, Nigeria

Breast cancer in sub-Saharan Africa: The current state and uncertain future

Breast cancer is the commonest cause of global cancer-related deaths in women and a public health burden in sub-Saharan Africa (SSA). Although the disease incidence in SSA seems lower, mortality rates are disproportionately high in comparison to high-income countries. The global disease burden is growing, with SSA reporting the majority of cases; however, the dearth of information results in insufficient data which is barely representative of the actual disease burden in this population. Future incidence predictions assign the subregion with a majority of the cases and associated deaths. Breast cancer presents with racial and ethnic variations, and available evidence suggests geographical diversity and persistent risk factors that have barely been explored in SSA. Breast cancer is a complex genetic disease, but the genetic risk factors in the extant African population, which is the most genetically diverse population, is scant and of low quality. This review focuses on the burden, prevalence, detection, treatment, survival, biology, as well as risk factors, and reinforces the need for breast cancer-associated risk factor investigation and population-specific studies in SSA.

Collaborative Molecular Epidemiology Study of Metabolic Dysregulation, DNA Methylation, and Breast Cancer Risk Among Nigerian Women: MEND Study Objectives and Design

PURPOSE

To elucidate the role of metabolic dysregulation and associated DNA methylation changes on breast cancer risk and aggressive subtypes among Nigerian women. We describe the design and methods of a collaborative molecular epidemiology study of breast cancer in Nigerian hospitals.

METHODS

The Mechanisms for Novel and Established Risk Factors for Breast Cancer in Women of Nigerian Descent (MEND) study was designed as a matched case-control study of 350 patients, age 18 to 75 years, with newly diagnosed, treatment-naïve breast cancer and 350 age-matched healthy controls from surrounding geographic areas. Patients with breast cancer seen for initial diagnosis at four large tertiary hospitals in southwest Nigeria and one affiliated private hospital were recruited. Healthy female controls were selected from a cohort of 4,000 healthy women recruited as part of the Human Heredity and Health (H3) in Africa Chronic Kidney Disease Case-Control Study in Nigeria. Tumor and adjacent normal tissue, and blood and saliva samples were collected for molecular and epigenetic assays.

RESULTS

Although recruitment is ongoing, a total of 416 patients have been recruited to date, with tumor and blood samples obtained from at least 310 patients. Data on age-matched (± 6 months) controls have also been obtained and harmonized. Lipid assays for 350 pathologically verified cases and 350 age-matched controls is underway, and pathologic characterization of tumors (including immunohistochemistry for subtyping) is ongoing. Data on DNA methylation for tumors and adjacent normal tissue are expected by the end of the study period.

CONCLUSION

The MEND study will provide a unique, high-quality source of data to evaluate the contribution of metabolic dysregulation such as obesity, diabetes, hypertension, and metabolic syndrome to the biology of breast cancer among Nigerian women and foster collaborative studies relevant for women of African descent globally.

Characterization of hormonal receptors and human epidermal growth factor receptor-2 in tissues of women with breast cancer at Muhimbili National Hospital, Dar es salaam, Tanzania

Background

Breast cancer is a leading cause of morbidity and deaths among women worldwide. In Tanzania there is no published data on human epidermal growth receptor-2 (HER2/neu) expression in breast carcinoma. Hormonal receptors and HER2/neu status reportedly influence post-mastectomy adjuvant therapy and predict treatment outcome and prognosis. Here we evaluate hormonal receptors and HER-2 status in biopsies of women with breast cancer at Muhimbili National Hospital (MNH).

Methods

A cross-sectional study of female breast post-modified radical mastectomy (MRM)/incisional biopsies confirmed to be carcinoma at the Histopathology Unit (January–December 2013). Tissue blocks having poor morphology, without tumor, secondary tumors, cases outside the study period and male patients were excluded. Routine staining was done followed by immunohistochemistry for estrogen (ER), and progesterone (PgR) receptors and HER2. Data analyzed using Statistical Package for Social Sciences (SPSS).

Results

A total of 218 cases were confirmed to be carcinoma including 70 meeting inclusion criteria. Age at diagnosis ranged 18–75 years and mean age was 48.36 years. Majority (64.3%) were in the 36–55 years age-group. Histologically, most (88.6%) women had invasive ductal carcinoma including 43.1% of intermediate grade. A great majority (78%) were stage three. Due to logistical constrains, 75.7% (n = 53/70) cases where immunostained for hormones including 43.4% (ER+), 26.4% (PgR+), and 28% (ER+/PgR+). Furthermore, 65.7% (n = 46/70) cases were immunostained for HER-2 and 15.2% (n = 7/46) were positive, 45.6% were triple negative (ER-,PgR-,HER2-), 23.9% (ER+,PgR+,HER2-) or luminal B, 2.2% (ER+,PgR-,HER2+),13% (ER-,PgR-,HER2+) and 15% (ER+,PgR-,HER2-) with none being triple positive.

Conclusions

Hormonal receptors and HER2 expression at MNH appears to be comparable to previous Africans/African Americans reports but not with studies among Caucasians and the current proportion of triple negative breast carcinomas (TNBC) is higher than in a previous Tanzanian report and majority are luminal. HER2 over-expression is relatively common. It is strongly recommended that receptor status assessment be made routine for breast cancer patients at MNH.

Aggressive breast cancer in western Kenya has early onset, high proliferation, and immune cell infiltration

Background

Breast cancer incidence and mortality vary significantly among different nations and racial groups. African nations have the highest breast cancer mortality rates in the world, even though the incidence rates are below those of many nations. Differences in disease progression suggest that aggressive breast tumors may harbor a unique molecular signature to promote disease progression. However, few studies have investigated the pathology and clinical markers expressed in breast tissue from regional African patient populations.

Methods

We collected 68 malignant and 89 non-cancerous samples from Kenyan breast tissue. To characterize the tumors from these patients, we constructed tissue microarrays (TMAs) from these tissues. Sections from these TMAs were stained and analyzed using immunohistochemistry to detect clinical breast cancer markers, including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 receptor (HER2) status, Ki67, and immune cell markers.

Results

Thirty-three percent of the tumors were triple negative (ER-, PR-, HER2-), 59 % were ER+, and almost all tumors analyzed were HER2-. Seven percent of the breast cancer patients were male, and 30 % were <40 years old at diagnosis. Cancer tissue had increased immune cell infiltration with recruitment of CD163+ (M2 macrophage), CD25+ (regulatory T lymphocyte), and CD4+ (T helper) cells compared to non-cancer tissue.

Conclusions

We identified clinical biomarkers that may assist in identifying therapy strategies for breast cancer patients in western Kenya. Estrogen receptor status in particular should lead initial treatment strategies in these breast cancer patients. Increased CD25 expression suggests a need for additional treatment strategies designed to overcome immune suppression by CD25+ cells in order to promote the antitumor activity of CD8+ cytotoxic T cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2204-6) contains supplementary material, which is available to authorized users.

Epidemiologic and Clinical Profiles of Breast Diseases in Niger

This study aimed at characterizing epidemiologic and clinical profiles of breast diseases in Niger during the period of 2010–2013 at the National Hospital of Niamey. Medical records were abstracted for demographic, reproductive, clinical, and treatment information. A process map of patient navigation and barriers to seeking medical care was developed after interviewing 26 local health professionals who encounter and/or manage breast diseases. We identified 245 breast cancers and 122 other breast diseases. Mean age of breast cancer patients was 45.4 (±13.26 years) and that of breast diseases was 31(±12.5 years) with 1/3 of cancers under age 44. Infection-related diseases represented 24% of non-cancers. Male breast diseases represented 4.75% of diseases and 2.05% of cancers. Only 37.1% of cancers had histopathologic confirmation and 90% of cancer patients presented at advanced stages and mastectomy was performed for 66% of breast cancers. Patient and system barriers to care were common in diagnosing and treating breast diseases. Women in Niger have double burden of infectious breast diseases and emerging breast cancer. Younger age and late diagnosis are common features. Reducing barriers to access to care, down-staging of cancer, implementation of clinical guidelines for managing advanced cases are important needs for reducing breast cancer morbidity and mortality in Niger.

BRCA genetic screening in Middle Eastern and North African: mutational spectrum and founder BRCA1 mutation (c.798_799delTT) in North African

BACKGROUND

The contribution of BRCA1 mutations to both hereditary and sporadic breast and ovarian cancer (HBOC) has not yet been thoroughly investigated in MENA.

METHODS

To establish the knowledge about BRCA1 mutations and their correlation with the clinical aspect in diagnosed cases of HBOC in MENA populations. A systematic review of studies examining BRCA1 in BC women in Cyprus, Jordan, Egypt, Lebanon, Morocco, Algeria, and Tunisia was conducted.

RESULTS

Thirteen relevant references were identified, including ten studies which performed DNA sequencing of all BRCA1 exons. For the latter, 31 mutations were detected in 57 of the 547 patients ascertained. Familial history of BC was present in 388 (71%) patients, of whom 50 were mutation carriers. c.798_799delTT was identified in 11 North African families, accounting for 22% of total identified BRCA1 mutations, suggesting a founder allele. A broad spectrum of other mutations including c.68_69delAG, c.181T>G, c.5095C>T, and c.5266dupC, as well as sequence of unclassified variants and polymorphisms, was also detected.

CONCLUSION

The knowledge of genetic structure of BRCA1 in MENA should contribute to the assessment of the necessity of preventive programs for mutation carriers and clinical management. The high prevalence of BC and the presence of frequent mutations of the BRCA1 gene emphasize the need for improving screening programs and individual testing/counseling.

Breast cancer receptor status and stage at diagnosis in over 1,200 consecutive public hospital patients in Soweto, South Africa: a case series

Introduction

Estimates of the proportion of estrogen receptor negative (ERN) and triple-negative (TRN) breast cancer from sub-Saharan Africa are variable and include high values. Large studies of receptor status conducted on non-archival tissue are lacking from this region.

Methods

We identified 1218 consecutive women (91% black) diagnosed with invasive breast cancer from 2006–2012 at a public hospital in Soweto, South Africa. Immunohistochemistry based ER, progesterone receptor (PR) and human epidermal factor 2 (HER2) receptors were assessed at diagnosis on pre-treatment biopsy specimens. Mutually adjusted associations of receptor status with stage, age, and race were examined using risk ratios (RRs). ER status was compared with age-stratified US Surveillance Epidemiology and End Results program (SEER) data.

Results

35% (95% confidence interval (CI): 32–38) of tumors were ERN, 47% (45–52) PRN, 26% (23–29) HER2P and 21% (18–23) TRN. Later stage tumors were more likely to be ERN and PRN (RRs 1.9 (1.1-2.9) and 2.0 (1.3-3.1) for stage III vs. I) but were not strongly associated with HER2 status. Age was not strongly associated with ER or PR status, but older women were less likely to have HER2P tumors (RR, 0.95 (0.92-0.99) per 5 years). During the study, stage III + IV tumors decreased from 66% to 46%. In black women the percentage of ERN (37% (34–40)) and PRN tumors (48% (45–52)) was higher than in non-black patients (22% (14–31) and 34% (25–44), respectively, P = 0.004 and P = 0.02), which remained after age and stage adjustment. Age-specific ERN proportions in black South African women were similar to those of US black women, especially for women diagnosed over age 50.

Conclusion

Although a greater proportion of black than non-black South African women had ER-negative or TRN breast cancer, in all racial groups in this study breast cancer was predominantly ER-positive and was being diagnosed at earlier stages over time. These observations provide initial indications that late-stage aggressive breast cancers may not be an inherent feature of the breast cancer burden across Africa.

Receptor-defined subtypes of breast cancer in indigenous populations in Africa: a systematic review and meta-analysis

BACKGROUND

Breast cancer is the most common female cancer in Africa. Receptor-defined subtypes are a major determinant of treatment options and disease outcomes but there is considerable uncertainty regarding the frequency of poor prognosis estrogen receptor (ER) negative subtypes in Africa. We systematically reviewed publications reporting on the frequency of breast cancer receptor-defined subtypes in indigenous populations in Africa.

METHODS AND FINDINGS

Medline, Embase, and Global Health were searched for studies published between 1st January 1980 and 15th April 2014. Reported proportions of ER positive (ER+), progesterone receptor positive (PR+), and human epidermal growth factor receptor-2 positive (HER2+) disease were extracted and 95% CI calculated. Random effects meta-analyses were used to pool estimates. Fifty-four studies from North Africa (n=12,284 women with breast cancer) and 26 from sub-Saharan Africa (n=4,737) were eligible. There was marked between-study heterogeneity in the ER+ estimates in both regions (I2>90%), with the majority reporting proportions between 0.40 and 0.80 in North Africa and between 0.20 and 0.70 in sub-Saharan Africa. Similarly, large between-study heterogeneity was observed for PR+ and HER2+ estimates (I2>80%, in all instances). Meta-regression analyses showed that the proportion of ER+ disease was 10% (4%-17%) lower for studies based on archived tumor blocks rather than prospectively collected specimens, and 9% (2%-17%) lower for those with ≥ 40% versus those with <40% grade 3 tumors. For prospectively collected samples, the pooled proportions for ER+ and triple negative tumors were 0.59 (0.56-0.62) and 0.21 (0.17-0.25), respectively, regardless of region. Limitations of the study include the lack of standardized procedures across the various studies; the low methodological quality of many studies in terms of the representativeness of their case series and the quality of the procedures for collection, fixation, and receptor testing; and the possibility that women with breast cancer may have contributed to more than one study.

CONCLUSIONS

The published data from the more appropriate prospectively measured specimens are consistent with the majority of breast cancers in Africa being ER+. As no single subtype dominates in the continent availability of receptor testing should be a priority, especially for young women with early stage disease where appropriate receptor-specific treatment modalities offer the greatest potential for reducing years of life lost. Please see later in the article for the Editors' Summary.

Histopathological profile of breast cancer in an African population

BACKGROUND

Currently breast cancer (BRCA) still remain the most commonly diagnosed female cancer globally with a significant geographic, racial and ethnical variations in its incidence.

AIM

This article examines the frequency and histological types and grades of BRCA in a pioneer teaching Hospital in Delta State, Nigeria.

MATERIALS AND METHODS

H and E stained-slides of breast biopsies diagnosed at the Central Hospital, Warri from 2005 to 2011 were archived and studied. Request forms were scrutinized for clinical bio-data, diagnosis and histological sections were analyzed. Data obtained were analyzed using the Statistical Package for the Social Sciences version 17 statistical package (SPSS) Incorporated, Chicago, Illinois, USA, and value presented descriptively.

RESULTS

During this period, 905 breast lesions were seen. Out of this, 261 were BRCAs, of which 260 cases were females and one case was a male. The peak age incidence for BRCA and its variants was 40-49 years accounting for (n = 94/261; 36%). The mean age of BRCA was 46 years (6.2). Invasive carcinoma of no special type (NST) was the most commonly encountered histological group of breast carcinoma constituting (n = 203/261, 77.7%) with the high grade invasive ductal carcinoma as the leading diagnosis.

CONCLUSION

Majority of BRCAs encounter was invasive ductal carcinoma of NST with bulk of patients presenting in Stages III and IV.

Breast cancer in Sub-Saharan Africa: opportunities for prevention

Although breast cancer is a growing health problem in sub-Saharan Africa, reasons for its increased occurrence remain unclear. We reviewed the published literature to determine the magnitude of the increase in breast cancer, associated risk factors (including for breast cancer subtypes), and ways to reduce incidence and mortality. Some of the increased breast cancer occurrence likely reflects that women are living longer and adopting lifestyles that favor higher incidence rates. However, a greater proportion of breast cancers occur among premenopausal women as compared to elsewhere, which may reflect unique risk factors. Breast cancers diagnosed among African women reportedly include a disproportionate number of poor prognosis tumors, including hormone receptor negative, triple negative, and core basal phenotype tumors. However, it is unclear how lack of standardized methods for tissue collection, fixation, and classification contribute to these rates. Given appropriate classifications, it will be of interest to compare rates with other populations and to identify risk factors that relate to specific tumor subtypes. This includes not only risk factors that have been recognized in other populations but also some that may play unique roles among African women, such as genetic factors, microbiomata, xenoestrogens, hair relaxers, and skin lighteners. With limited opportunities for effective treatment, a focus is needed on identifying etiologic factors that may be amenable to intervention. It will also be essential to understand reasons why women delay seeking care after the onset of symptoms and for there to be educational campaigns about the importance of early detection.

Women's cultural perceptions and attitudes towards breast cancer: Northern Ghana

This study investigates problems confronting breast cancer awareness in Ghana by ascertaining how societal perceptions and attitudes influence women's awareness of breast cancer in the Kassena-Nankana district. Data were gathered through focus group interviews and documentary analysis of current practices within the region. The data were then thematically analysed following an inductive analytical framework. The study concludes that women's perceptions of and attitudes towards breast cancer and its treatment are influenced by a myriad of economic and socio-cultural factors, which practitioners need to take into account when planning public health initiatives. There are a number of economic challenges facing breast cancer education and awareness programmes due to a lack of adequate numbers of specialized health personnel and breast cancer screening facilities in the district. Additionally, socio-cultural factors such as the absence of biomedical terminology in the local language, gender inequality and the prevailing influence of traditional health practitioners further compound the situation. Knowledge, awareness and attitudes of women towards breast cancer can also be improved if husbands of married women and respective community compound heads are targeted by public health educationists to get actively involved in education and awareness campaigns. The need to incorporate indigenous languages in public health educational materials for breast cancer in remote communities of deprived districts of Ghana is also recommended.

Mastectomy for management of breast cancer in Ibadan, Nigeria

Background

Modified radical mastectomy remains the standard therapeutic surgical operation for breast cancer in most parts of the world. This retrospective study reviews mastectomy for management of breast cancer in a surgical oncology division over a ten year period.

Methods

We reviewed the case records of consecutive breast cancer patients who underwent mastectomy at the Surgical Oncology Division, University College Hospital (UCH) Ibadan between November 1999 and October 2009.

Results

Of the 1226 newly diagnosed breast cancer patients over the study period, 431 (35.2%) patients underwent mastectomy making an average of 43 mastectomies per year. Most patients were young women, premenopausal, had invasive ductal carcinoma and underwent modified radical mastectomy as the definitive surgical treatment. Prior to mastectomy, locally advanced tumors were down staged in about half of the patients that received neo-adjuvant combination chemotherapy. Surgical complication rate was low. The most frequent operative complication was seroma collection in six percent of patients. The average hospital stay was ten days and most patients were followed up at the surgical outpatients department for about two years post-surgery.

Conclusions

There was low rate of mastectomy in this cohort which could partly be attributable to late presentation of many patients with inoperable local or metastatic tumors necessitating only palliative or terminal care. Tumor down-staging with neo-adjuvant chemotherapy enhanced surgical loco-regional tumor control in some patients. The overall morbidity and the rates of postoperative events were minimal. Long-term post-operative out-patients follow-up was not achieved as many patients were lost to follow up after two years of mastectomy.

Clinical features and pattern of presentation of breast diseases in surgical outpatient clinic of a suburban tertiary hospital in South-west Nigeria

Objective:

To characterize the clinical features and pattern of presentation of breast diseases as observed in our practice.

Materials and Methods:

A prospective study of 121 consecutive patients with breast complaints presenting in our Surgical Outpatient Clinics. The relevant data were collected by two surgeons using the prescribed forms and was analyzed using Epi Info 2003, Mann-Whitney (test of two groups) Chi-squared and Fishers exact test was used to compare parameters of benign and malignant groups. P value <0.05 was considered as significant.

Results:

One hundred and nineteen patients were females, two were males. The age range was 14-70 years. Forty two (34.7%) patients were in the 21-30 year age group. The commonest symptoms were breast lump in 111 (91.7%) patients, and breast pain in 28 (23.1%) patients. Breast pain was a significant presenting complaint in patients with breast malignancy (P=.026). On clinical examination 103 (85.1%) patients had palpable lumps, and seven patients were normal. Forty four patients (36.3%) had malignant disease, seventy patients (57.8%) had benign breast diseases and seven were normal. Fifty nine of the 70 benign diseases were fibroadenoma. One hundred and three patients (85%) had appropriate therapy, while 18 patients (14.8%), including eight with malignant disease absconded.

Conclusion:

In the study, a breast lump was the commonest clinical feature of breast disease. Over 60% of these were benign. Breast pain was a statistically significant presentation in patients with malignant breast disease. One in seven of the patients absconded.

Global breast cancer: the lessons to bring home

Breast cancer is the most common cancer affecting women globally. This paper discusses the current progress in breast cancer in Western countries and focuses on important differences of this disease in low- and middle-income countries (LMCs). It introduces several arguments for applying caution before globalizing some of the US-adopted practices in the screening and management of the disease. Finally, it suggests that studies of breast cancer in LMCs might offer important insights for a more effective management of the problem both in developing as well as developed countries.

A nation-wide multicenter 10-year (1999-2008) retrospective clinical epidemiological study of female breast cancer in China

BACKGROUND

According to the very limited cancer registry, incidence and mortality rates for female breast cancer in China are regarded to be increasing especially in the metropolitan areas. Representative data on the breast cancer profile of Chinese women and its time trend over years are relatively rare. The aims of the current study are to illustrate the breast cancer profile of Chinese women in time span and to explore the current treatment approaches to female breast cancer.

METHODS

This was a hospital-based nation-wide and multi-center retrospective study of female primary breast cancer cases. China was divided into 7 regions according to the geographic distribution; from each region, one tertiary hospital was selected. With the exception of January and February, one month was randomly selected to represent each year from year 1999 to 2008 at every hospital. All inpatient cases within the selected month were reviewed and related information was collected based on the designed case report form (CRF). The Cancer Hospital/Institute, Chinese Academy of Medical Sciences (CICAMS) was the leading hospital in this study.

RESULTS

Four-thousand two-hundred and eleven cases were randomly selected from the total pool of 45,200 patients and were included in the analysis. The mean age at diagnosis was 48.7 years (s.d. = 10.5 yrs) and breast cancer peaked in age group 40-49 yrs (38.6%). The most common subtype was infiltrating ductal carcinoma (86.5%). Clinical stage I & II accounted for 60.6% of 4,211 patients. Three-thousand five-hundred and thirty-four cases had estrogen receptor (ER) and progestin receptor (PR) tests, among them, 47.9% were positive for both. Two-thousand eight-hundred and forty-nine cases had human epidermal growth factor receptor 2(HER-2) tests, 25.8% of them were HER-2 positive. Among all treatment options, surgery (96.9% (4,078/4,211)) was predominant, followed by chemotherapy (81.4% (3,428/4,211). Much less patients underwent radiotherapy (22.6% (952/4,211)) and endocrine therapy (38.0% (1,599/4,211)).

CONCLUSIONS

The younger age of breast cancer onset among Chinese women and more advanced tumor stages pose a great challenge. Adjuvant therapy, especially radiotherapy and endocrine therapy are of great unmet needs.

Systematic review of breast cancer biology in developing countries (part 1): Africa, the middle East, eastern europe, Mexico, the Caribbean and South america

There has been no systematic appraisal of ethnicity-based variations in breast cancer (BC) biology amongst women from developing countries. A qualitative systematic review was conducted of breast cancer size, stage, grade, histological type, extra-mammary involvement, hormone receptor status as well as patient demographics. This review includes patients from Africa, the Middle East, Eastern Europe, Mexico, the Caribbean and South America. BC in these regions present at an earlier age with large aggressive tumours. Distant metastases are frequently present at the time of diagnosis. African women have a higher frequency of triple negative tumours. Over half of Middle Eastern women have lymph node involvement at the time of diagnosis. Despite experiencing a lower incidence compared to the Ashkenazi Jewish population, Palestinian women have poorer five-year survival outcomes. The majority of women from Mexico and South America have stage two or three disease whilst over sixty percent of women from Eastern Europe have either stage one or stage two disease. The biological characteristics of BC in the Caribbean cannot be fully assessed due to a paucity of data from the region. BC amongst the developing world is characterised by an early peak age of onset with aggressive biological characteristics. Strategies that improve breast cancer awareness, address amenable risk factors and improve early detection are essential.

Interactions among genes, tumor biology and the environment in cancer health disparities: examining the evidence on a national and global scale

Cancer incidence and mortality rates show great variations across nations and between population groups. These variations are largely explained by differences in age distribution, diet and lifestyle, access to health care, cultural barriers and exposure to carcinogens and pathogens. Cancers caused by infections are significantly more common in developing than developed countries, and they overproportionally affect immigrant populations in the USA and other countries. The global pattern of cancer is not stagnant. Instead, it is dynamic because of fluctuations in the age distribution of populations, improvements in cancer prevention and early detection in affluent countries and rapid changes in diet and lifestyle in parts of the world. For example, increased smoking rates have caused tobacco-induced cancers to rise in various Asian countries, whereas reduced smoking rates have caused these cancers to plateau or even begin to decline in Western Europe and North America. Some population groups experience a disproportionally high cancer burden. In the USA and the Caribbean, cancer incidence and mortality rates are excessively high in populations of African ancestry when compared with other population groups. The causes of this disparity are multifaceted and may include tumor biological and genetic factors and their interaction with the environment. In this review, we will discuss the magnitude and causes of global cancer health disparities and will, with a focus on African-Americans and selected cancer sites, evaluate the evidence that genetic and tumor biological factors contribute to existing cancer incidence and outcome differences among population groups in the USA.

Breast cancer burden in central Sudan

Breast cancer is a worldwide disease resulting in many deaths. Although breast cancer incidence is lower in Sub-Saharan African countries than in developed countries, African women are more likely than women in the developed world to be diagnosed at later stages of the disease and, thus, are more likely to die from it. This is due to the lack of awareness by women, accessibility to screening methods, and availability of African-based research findings that would influence decision making at the governmental level. This descriptive study was undertaken to shed light on the type, stage and age distribution of breast cancer at diagnosis in women living in central Sudan encompassing al-Gezira, Blue Nile, White Nile, and Sennar States. Cases comprised 1255 women from central Sudan diagnosed with breast cancer and referred to and treated at Institute of Nuclear Medicine, Molecular Biology, and Oncology, from January 1999 to December 2006. Data revealed that 74% of the women were <50 years old or premenopausal. Invasive ductal carcinoma was the most common pathology (82%) and women presenting with stage III or higher tumors that had already metastasized, while ductal carcinoma in situ was the least prevalent (0.5%) finding. Estrogen and progesterone receptors expression were performed on a limited number of samples and the overwhelming majority of cases were observed to be negative for estrogen and progesterone receptors expression.

Pattern of presentation and survival of breast cancer in a teaching hospital in north Western Nigeria

OBJECTIVES

Developing countries are experiencing demographic and epidemiologic transition and the prevalence of non-communicable diseases especially cancers which is on the increase. Breast cancer is the most common and lethal malignancy in developing countries with varying presentation. This study aims to determine the pattern of presentation and survival of breast cancer patients in North Western Nigeria.

METHODS

A five-year retrospective review of breast cancer records from 2001-2005 was conducted. Relevant information was retrieved and analyzed using statistical package for social science software. Manchester stage III and IV were classified as advance disease. Survival analysis was carried out with survival defined as the time between the date of commencement of treatment and the date of last follow-up or death.

RESULTS

Most of the patients were in the 4th and 5th decades 58 (57.4%) with a mean age of 44.5±13 years. Majority of the patients were females 99 (96.1%). One of the four males had invasive lobular carcinoma while the others presented with invasive ductal carcinoma 3 (75.0%). Most of the patients were premenopausal 62 (62.6%) and were presented late with advanced breast cancer disease 64 (62.1%). The left breast was more affected 64 (62.1%), and the upper outer quadrant was mostly involved 48 (60.7%), followed by the areola, 43(41.7%) either singly or in combination. Invasive ductal carcinoma was detected in 85 (82.5%) cases and was the predominant histological finding. Survival rate beyond 30 months was observed in 24.5% of cases and 100% for advanced and early breast cancer respectively, (p=0.0001). The overall survival rate beyond 36 months was 70.4% and postmenopausal patients (70.6%) had better survival beyond 36 months than premenopausal (68.5%) patients (p=0.05).

CONCLUSION

The overall survival rate was low and patients with early breast cancer had better survival than those with advanced disease. Majority of the patients were young premenopausal women with advanced breast cancer.

Clinical and epidemiologic profile of breast cancer in Tanzania

PURPOSE

breast cancer is a highly heterogeneous disease globally. Public health prevention measures require an understanding of the burden of breast cancer and its risk factors. The purpose of this study was to describe the clinical, pathologic, and epidemiologic characteristics of breast cancer patients in Tanzania.

METHODS

data was abstracted from the medical records of all breast cancer patients attending Ocean Road Cancer Institute (ORCI) over a 2-year period from July 2007 to June 2009. Tumor tissue paraffin blocks were collected for all patients with available tissues for the determination of estrogen receptor (ER) and progesterone receptor (PR). Data for all patients was analyzed descriptively and by using unconditional logistic regression, by comparing early stage (ES), defined as stages I and II and late stage (LS), defined as stages III and IV patients to obtain odds ratios (ORs), 95% confidence intervals (CIs), and P-values.

RESULTS

among the 488 patients, stage was determined for 356~patients, 90.7% of whom presented in LS. Of the 57 tumor tissues, 49.1% were ER-/PR-. Patients with ulceration (OR = 4.97; 95% CI= 1.07, 23.04; p=0.04) and peau d'orange (OR= 6.78; 95{\%} CI $=$ 1.48, 31.17; p=0.01) were more likely to present in LS rather than ES. Male breast cancer accounted for 2.9% of all breast cancers and inflammatory breast cancer (IBC) comprised 4.3-5.5% of cases based on registered t4d diagnosis or the criteria of IBC signs, if t4d was not reported in the medical records.

CONCLUSION

most breast cancer patients in Tanzania are diagnosed at advanced disease stages with about half of the tumors being ER-/PR-. These data strongly support that reducing barriers to care, down-staging of disease at diagnosis, implementation of clinical guidelines for management of advanced cases, and palliative care are the four most essential factors that need to be addressed to reduce morbidity and mortality from breast cancer in Tanzania. Further research is needed to quantify the magnitude and molecular features of two relatively rare forms of breast cancer that may account for a greater proportion of the burden of breast cancer in Tanzania compared to the USA and Western Europe: male breast cancer and IBC.

Population differences in breast cancer: survey in indigenous African women reveals over-representation of triple-negative breast cancer

PURPOSE

Compared with white women, black women experience a disproportionate burden of aggressive breast cancer for reasons that remain unknown and understudied. In the first study of its kind, we determined the distribution of molecular subtypes of invasive breast tumors in indigenous black women in West Africa.

PATIENTS AND METHODS

The study comprised 507 patients diagnosed with breast cancer between 1996 and 2007 at six geographic regions in Nigeria and Senegal. Formalin-fixed and paraffin-embedded sections were constructed into tissue microarrays and immunostained with 15 antibodies. Five molecular subtypes were determined, and hierarchical cluster analysis was conducted to explore subgroups for unclassified cases.

RESULTS

The mean (+/- standard deviation) age of 378 patients in the first cohort was 44.8 +/- 11.8 years, with the majority of women presenting with large (4.4 +/- 2.0 cm) high-grade tumors (83%) in advanced stages (72% node positive). The proportions of estrogen receptor (ER) -positive, progesterone receptor-positive, and human epidermal growth factor receptor 2 (HER2) -positive tumors were 24%, 20%, and 17%, respectively. Triple negativity for these markers was predominant, including basal-like (27%) and unclassified subtype (28%). Other subtypes were luminal A (27%), luminal B (2%), and HER2 positive/ER negative (15%). The findings were replicated in the second cohort of 129 patients. The unclassified cases could be grouped into a bad prognosis branch, with expression of vascular endothelial growth factor, B-cell lymphoma extra-large protein, and Cyclin E, and a good prognosis branch, with expression of B-cell lymphoma protein 2 and Cyclin D1.

CONCLUSION

These findings underscore the urgent need for research into the etiology and treatment of the aggressive molecular subtypes that disproportionately affect young women in the African diaspora.

Adaptive variation regulates the expression of the human SGK1 gene in response to stress

The Serum and Glucocorticoid-regulated Kinase1 (SGK1) gene is a target of the glucocorticoid receptor (GR) and is central to the stress response in many human tissues. Because environmental stress varies across habitats, we hypothesized that natural selection shaped the geographic distribution of genetic variants regulating the level of SGK1 expression following GR activation. By combining population genetics and molecular biology methods, we identified a variant (rs9493857) with marked allele frequency differences between populations of African and European ancestry and with a strong correlation between allele frequency and latitude in worldwide population samples. This SNP is located in a GR-binding region upstream of SGK1 that was identified using a GR ChIP-chip. SNP rs9493857 also lies within a predicted binding site for Oct1, a transcription factor known to cooperate with the GR in the transactivation of target genes. Using ChIP assays, we show that both GR and Oct1 bind to this region and that the ancestral allele at rs9493857 binds the GR-Oct1 complex more efficiently than the derived allele. Finally, using a reporter gene assay, we demonstrate that the ancestral allele is associated with increased glucocorticoid-dependent gene expression when compared to the derived allele. Our results suggest a novel paradigm in which hormonal responsiveness is modulated by sequence variation in the regulatory regions of nuclear receptor target genes. Identifying such functional variants may shed light on the mechanisms underlying inter-individual variation in response to environmental stressors and to hormonal therapy, as well as in the susceptibility to hormone-dependent diseases.

Susceptibility to many common human diseases including hypertension, heart disease, and the metabolic syndrome is associated with increased neuroendocrine signaling in response to environmental stressors. A key component of the human stress response involves increased systemic glucocorticoid secretion that in turn leads to glucocorticoid receptor (GR) activation. As a result, a variety of GR-expressing cell types undergo gene expression changes, thereby providing an integrated physiological response to stress. The SGK1 gene is a well-established GR target that promotes cellular homeostasis in response to stress. Here, we use a combination of population genetics and molecular biology approaches to identify an SNP (rs9493857) in a distant SGK1 GR-binding region with unusually large differences in allele frequency between populations of European and African ancestry. Furthermore, rs9493857 shows a strong correlation between allele frequency and distance from the equator, a pattern consistent with a varying selective advantage across environments. Indeed, the ancestral allele at rs9493857 results in increased GR-binding and glucocorticoid-regulated gene expression, suggesting that an increased stress response (i.e., glucocorticoid responsiveness) was advantageous in ancestral human populations. We speculate that, in modern times, such variation could favor the negative effects of a heightened glucocorticoid response, potentially predisposing individuals to chronic diseases such as metabolic syndrome and hypertension.

BRCA1 mutations in Algerian breast cancer patients: high frequency in young, sporadic cases

Breast cancer rates and median age of onset differ between Western Europe and North Africa. In Western populations, 5 to 10 % of breast cancer cases can be attributed to major genetic factors such as BRCA1 and BRCA2, while this attribution is not yet well defined among Africans. To help determine the contribution of BRCA1 mutations to breast cancer in a North African population, we analysed genomic DNA from breast cancer cases ascertained in Algiers. Both familial cases (at least three breast cancers in the same familial branch, or two with one bilateral or diagnosed before age 40) and sporadic cases less than 38 years of age were studied. Complete sequencing plus quantitative analysis of the BRCA1 gene was performed. 9.8 % (5/51) of early-onset sporadic and 36.4 % (4/11) of familial cases were found to be associated with BRCA1 mutations. This is in contrast 10.3 % of French HBOC families exhibiting a BRCA1 mutation. One mutation, c.798_799delTT, was observed in two Algerian families and in two families from Tunisia, suggesting a North African founder allele. Algerian non-BRCA1 tumors were of significantly higher grade than French non-BRCA tumors, and the age at diagnosis for Algerian familial cases was much younger than that for French non-BRCA familial cases. In conclusion, we observed a much higher frequency of BRCA1 mutations among young breast cancer patients than observed in Europe, suggesting biological differences and that the inclusion criterea for analysis in Western Europe may not be applicable for the Northern African population.

Parity and breastfeeding are protective against breast cancer in Nigerian women

As the relation between reproductive factors and breast cancer risk has not been systematically studied in indigenous women of sub-Saharan Africa, we examined this in a case–control study in Nigeria. In-person interviews were conducted using structured questionnaires to collect detailed reproductive history in 819 breast cancer cases and 569 community controls between 1998 and 2006. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI). Compared with women with menarcheal age <17 years, the adjusted OR for women with menarcheal age ⩾17 years was 0.72 (95% CI: 0.54–0.95, P=0.02). Parity was negatively associated with risk (P-trend=0.02) but age at first live birth was not significant (P=0.16). Importantly, breast cancer risk decreased by 7% for every 12 months of breastfeeding (P-trend=0.005). It is worth noting that the distribution of reproductive risk factors changed significantly from early to late birth cohorts in the direction of increasing breast cancer incidence. Our findings also highlight the heterogeneity of breast cancer aetiology across populations, and indicate the need for further studies among indigenous sub-Saharan women.

Early onset of breast cancer in a group of British black women

Since there are no published data on breast cancer in British black women, we sought to determine whether, like African-American women, they present at a younger age with biologically distinct disease patterns. The method involved a retrospective review of breast cancer to compare age distributions and clinicopathological features between black women and white women in the UK, while controlling for socioeconomic status. All women presented with invasive breast cancer, between 1994 and 2005, to a single East London hospital. Black patients presented significantly younger (median age of 46 years), than white patients (median age of 67 years (P=0.001)). No significant differences between black and white population structures were identified. Black women had a higher frequency of grade 3 tumours, lymph node-positive disease, negative oestrogen receptor and progesterone receptor status and basal-like (triple negative status) tumours. There were no differences in stage at presentation; however, for tumours of ⩽2 cm, black patients had poorer survival than white patients (HR=2.90, 95% CI 0.98–8.60, P=0.05). Black women presented, on average, 21 years younger than white women. Tumours in younger women were considerably more aggressive in the black population, more likely to be basal-like, and among women with smaller tumours, black women were more than twice as likely to die of their disease. There were no disparities in socioeconomic status or treatment received. Our findings could have major implications for the biology of breast cancer and the detection and treatment of the disease in black women.