DETERMINATION OF TRIPLE NEGATIVE BREAST CANCERS AND THEIR SUBTYPES SEEN AT THE JOS UNIVERSITY TEACHING HOSPITAL, JOS, BETWEEN JANUARY 2010 AND DECEMBER 2012

Abstract

Introduction: Breast cancer is the most common invasive cancer in women worldwide. It also
leads as a cause of cancer deaths in this gender. The treatment of breast cancer has been
modified significant to conservative treatment owing to the presence of micro metastasis at
even earlier stages of the disease. These novel medical treatments are hinged on characterizing
breast cancer molecularly. Estrogen receptor (ER), Progesterone receptor (PR), and Human
epidermal growth factor 2 receptor (HER2) are the commonest immuno-markers used. Failure
of the cancer cells to stain positively for these three receptors, earns a breast cancer the triple
negative designation, an aggressive type of the cancer with the worst prognosis. Furthermore
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the basal subtype of triple negative breast cancer has worse clinical outlook than the non-basal
subtype. Characterizing this heterogeneous cancer would aid in choosing appropriate care for
individual patients in our locality. This is because African cases of the disease have been
associated with poorer survival.
Aims and Objectives: To determine the frequency of triple negative breast cancers (TNBC)
and their subtypes, at the Jos University Teaching Hospital, between January 2010 and
December 2012. And also to further determine the relationship of TNBC to age, gender,
histological type, and histological grade.
Materials and methods: Histologically diagnosed breast cancers at the Jos University
Teaching Hospital, between 2010 and 2012, were retrieved from the archives. Cases with
adequate biodata and with sufficient tissue block for immunohistochemistry made up the
samples for this study. Archival formalin fixed and paraffin embedded tissue blocks were
retrieved. H&E staining was done, to confirm the diagnosis of breast cancer.
Immunoperoxidase staining for ER, PR, & HER2 was carried out using the Avidin-Biotin method.
Samples with negative staining for these three antibodies were further stained with CK5/6, a
basal biomarker for triple negative breast cancers.
Results: Up to 4,137 histology samples were received at the Jos University Teaching Hospital
during the period of the study. Three hundred and sixty seven (367, 8.87%) of these were
breast samples. Ninety six (96) cases (26.16% of all breast biopsies, 2.32% of all histology
samples) were diagnosed as breast cancers. Up to 63(65.63%) cases of breast cancers met the
inclusion criteria. All 96 malignancies were female breast cancers. The age range was 28-74
years with mean age of 46.7+11.1 years. The median age was 46 years. Invasive ductal
carcinoma of no special type (NST) was the most common histological type of breast cancer,
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accounting for 54(85.7%) cases. Most of the carcinomas were grade 2, accounting for
29(46.0%) cases. Triple Negative Breast Cancers (TNBC) accounted for 26 (41.3%) cases,
which is lower than 37(58.7%) cases of non-Triple Negative Breast Cancers (nTNBC). Fifteen
(57.7%) of TNBC stained positively for CK 5/6, while 11(43.3%) were negative.
Conclusion: The relatively high percentage of TNBC, as well as greater number of basal
subtype of TNBC is indicative of poor prognosis. These molecular indicators are however not
found to be associated with age, histological type, or histological grade. Generalized approach
to treatment for our women with breast cancer therefore would not be helpful as individualized
targeted therapy or chemotherapy is indicated for an individual case of the disease.