Histological Features and Tissue Microarray Taxonomy of Nigerian Breast Cancer Reveal Predominance of the High-Grade Triple-Negative Phenotype

INTRODUCTION

Little is known about the biology, molecular profile and hence optimal treatment of African Nigerian breast cancer. The aim of this work, therefore, was to characterize the histology and molecular profile of Nigerian breast cancer.

METHODS

Breast carcinomas from women at 6 centres of similar tribal origin in Nigeria were reviewed and assembled into tissue microarrays (TMAs), and sections were stained for hormone receptors, i.e. estrogen receptor (ER)α, ERβ1, ERβ progesterone receptor (PR) and androgen receptor, cyclin D, HER2, Ki67 and cytokeratins (CKs), i.e. CK5/6 and CK14 (basal) and CK18 and 19 (luminal).

RESULTS

A total of 835 tumours were analysed. The mean age at diagnosis was 48.62 ± 12.41 years. The most common histological subtype was ductal NST (no-special-type) carcinoma (87.3%). Over 90% of the tumours were grade 2 or 3. The predominant molecular phenotype was the non-basal, triple-negative type (47.65%) followed by the HER2-positive group (19.6%). The percentage of ER-, PR- and HER2-positive tumours was 22.4, 18.9 and 18.8%, respectively.

CONCLUSION

Nigerian breast cancer predominantly has a high-grade, triple-negative profile. It occurs at a younger age and bears similarities at the molecular level to pre-menopausal breast cancer in white women, with remarkably lower levels of ERβ expression. The early presentation and histological and molecular phenotype may explain the poor prognosis, and tailoring treatment strategies to target this unique profile are required.

P3-04-01: Molecular Characterization of African Breast Cancer; Results from a Large Tissue Microarray Study

Introduction: Breast cancer in African women has been understudied for decades. Evidence derived mainly from studies on African-American women, supports that tumours of black women are biologically different and more aggressive than those occurring in the white population. Of the 4 main taxonomic groups of breast cancer, basal tumours are more represented in those women. In the present state of knowledge, very little is known about the biology and molecular profile of breast cancer in Africa. The aim of this study was to test the hypothesis that the molecular profile of African breast cancer is distinct from its Western counterpart. This was achieved by collecting a large cohort of breast carcinomas from an indigenous African population for phenotypical characterization and testing for expression of potential predictive and prognostic markers.

Methods: Breast tumours were collected via collaboration with five centres in Nigeria (the most populous country in Africa) and assembled into tissue microarrays (TMAs). All tumours were reviewed by a specialist breast pathologist following the Royal College of Pathologists (RCPath) guidelines to confirm diagnosis, type, grade and nodal status. Patients age, tumour size and clinical data, where available, were collected from the original pathology reports and case notes. Representative tumour areas were selected and marked for TMA construction. TMA sections were stained for a range of markers including hormone receptors (ERα, ERβ, PR, AR), cyclin D, HER2, Ki67, bcl2, basal (CK5/6, CK14) and luminal cytokeratins (CK18, 19).

Results: A total of 830 tumours were assembled into TMAs. The mean age at diagnosis was 47.69yrs with 58% of patients presenting under the age of 50. Only 8.5% of tumours were of grade 1. Most tumours (87%) were of ductal no special type, followed by lobular and metaplastic carcinomas. The majority of the tumours were ERα, PR and HER2 negative (77%, 80% and 81% respectively). The triple negative tumours were the predominant phenotype (55.6%). Luminal A type tumours comprised 24.3% followed by the HER2 positive (13.9%) and luminal B tumours (6.2%). The differences of all those parameters were statistically highly significant (p<0.001). Most tumours expressed ERß including 75% of those that were ERα/PR negative. A large proportion of the tumours (22%) were of the basal phenotype of which two thirds were also triple negative. Over half of the triple negative tumours were also node positive.

Hierarchal cluster analysis showed the basal tumours dendrogram to comprise two groups; one showing clustering of ***ERα/PR/HER2 and the second showing clustering of ERß with CK5 and CK14.

Conclusion: To our knowledge, this is largest and most comprehensive study of African breast cancer to date. Our data confirms the hypothesis that African breast cancer is biologically distinct and shows remarkable differences in histological type, grade, hormone receptors & HER2 status when compared with breast cancer in white women. The early age at presentation, predominance of high grade and triple negative, but not necessarily basal phenotype, may explain the poor prognosis and requires tailoring treatment strategies to target this unique profile.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-04-01.

The spectrum of malignant neoplasms in Ekiti State, south-west Nigeria

BACKGROUND

Geographic pathology is an accepted basis for unravelling trends of disease patterns. Proper documentation at the initial stage assists in establishing a foundation data. The authors are not aware of a documented pattern of malignant neoplasm in Ekiti State.

OBJECTIVE

The aim of this study is to update the available literature on malignant neoplasms and compare our findings with previous work done by other investigators.

METHODS

The estimates are based on a systematic retrospective survey of cancer cases identified in the Pathology Laboratories of Federal Medical Centre, Ido-Ekiti and University Teaching Hospital, Ado-Ekiti for the period; January 2002 to December 2009. The data recorded on each case were: source of information (histology or cytology), name, age, and sex, date of diagnosis and site of tumour. Tumour site and histology were coded according to the International Classification of Diseases, ICD-10 for presentation in tabular form.

RESULTS

A total of 498 cancers were recorded. There were 177 (35.5%) males with average age of 54.5 years and 321 (64.5%) females with average age of 48.6 years. The estimated Crude Incidence (CI) rates for all cancer sites are 14.7 for males and 27.4 for females, per 100,000 population. In males, the most frequent cancer is prostate cancer (37.9%) followed by cancer of the liver (10.7%) and NonHodgkin's Lymphoma, NHL (7.9%). In females, the most common cancer is that of the breast (49.3%) followed by the cervix (8.5%) and the ovary (5.32%). A total of 28 childhood cancers were registered (17 males, 11 females). The most frequent tumours were Burkitt's lymphoma (8 cases) and soft tissue sarcomas (3 cases).

CONCLUSION

This study shows that malignant neoplasms are not uncommon in Ekiti State. There is underreporting of cases as the crude incidence rates are low. This study will serve as baseline to more population-based studies in future.

Seroprevalence of hepatitis B surface antigenemia among health care workers in a Nigerian tertiary health institution

OBJECTIVE

The aim of this study was to determine the seroprevalence of Hepatitis B surface antigenaemia among the health care workers at the Federal Medical Centre, Ido-Ekiti, Nigeria.

DESIGN AND METHOD

The study was carried out on all the staff members in the employment of the Federal Medical Center, Ido Ekiti, Nigeria as at 30th April 2003. Data were collected by administering a set of questionnaire to every member of staff. Blood samples (3mls) were taken from the left cubital fossa of all the respondents and Hepatitis B surface antigen status determined using the agglutination kits manufactured by Biotech Laboratories USA.

RESULTS

A total of 420 staff members were screened. 168 (40%) were males while 252 (60%) were females. Only 18 were found to be positive for Hepatitis B surface antigen giving a prevalence of 4.3%. 9 (50%) of those that were positive for Hepatitis B surface antigen were ward maids/attendants, 6 (33%) were nurses, 2 (11%) were administrative staff and 1 (6%) was a health record staff.

CONCLUSION

Health care workers are at increased risk of having hepatitis B infection. Health education should be carried out routinely in our hospitals to raise the awareness level among the hospital staff and standard safety measures such as sharps policy should be adopted in the handling of blood products and sharps.

Schistosomiasis presenting as acute appendicitis

BACKGROUND

Schistosomiasis is a chronic granulomatous inflammation that affects many systems in the body including the gastrointestinal tract. This study was carried out by reviewing all cases of schistosomal appendicitis, and documents any association with acute appendicitis.

OBJECTIVE

To review all cases of schistosomal appendicitis and document any possible asspciation with acute appendicitis.

DESIGN

A retrospective study.

SETTING

Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria, 1991 to 2004.

SUBJECTS

Eight hundred and forty three specimen of appendicectomy were reviewed. Thirty five of them were diagnosed as schistosomal appendicitis.

RESULTS

The involvement of the vermiform appendix by schistosomiasis found in 35/843 (4.2%) cases of all the appendicectomy specimen received in our histopathology laboratory between 1991 and 2004 shows that 23 of the cases (65.7%) had histologically proven acute appendicitis while the remaining 12 cases (34.3%) were schistosomiasis without active inflammation. The appendiceal wall oviposition is associated with submucosal fibrosis, narrowing of the lumen and subsequent acute suppurative inflammation in 17 cases while there were active granulomas with tissue eosinophilia in six cases.

CONCLUSION

This finding has demonstrated that though the frequency of appendix involvement is low considering the endemicity of schistosomiasis in our environment, however acute appendicitis may be caused by schistosomiasis.

Sero-prevalence of HIV antibodies in tuberculosis patients in Ile-Ife, Nigeria

BACKGROUND

The acquired immunodeficiency syndrome (AIDS) is of major public health concern worldwide more so in sub-Saharan Africa where there is an upsurge in the incidence of the disease. Reports from developed countries have shown that a close link exists between the human immunodeficiency virus (HIV) and pulmonary tuberculosis. No such study has ever been carried out in Ile-Ife, Nigeria.

OBJECTIVE

The study was designed to determine the prevalence of HIV infection among randomly selected tuberculosis patients seen in a Nigerian chest clinic using third generation ELISA kits that detect HIV-1 and HIV-2 strains.

RESULTS

Of the 79 subjects with confirmed active tuberculosis, 12.7% tested positive for HIV antibodies compared with 2.0% of subjects without tuberculosis designated as the control group--a value that is statistically significant (p < 0.05). Farmers, artisans and students contributed a large proportion of the seropositive sera. Although the seroprevalence rate of 12.7% is low compared with the rates from eastern and southern African countries, this value was threefold higher than 5.2% value reported in metropolitan Lagos--suggesting concern about the spread of HIV in a semi-urban centre such as Ile-Ife.

CONCLUSION

This study suggests that a close link exists between active tuberculosis and HIV infection in Ile-Ife, Nigeria which underscores the urgent need to monitor tuberculosis patients as the increase in the rate of new cases may indicate the spread of HIV infection. The study also recommends that an aggressive public awareness programme be undertaken to enlighten communities about the risk of TB/HIV infection.