IMMUNOHISTOCHEMICAL PROFILE OF BREAST CARCINOMAS AT UNIVERSITY OF CALABAR TEACHING HOSPITAL

Abstract

Background: Breast cancer is the commonest cancer in the female. The disease is
heterogeneous and this has been demonstrated by DNA micro-arrays that assesses the
intrinsic gene expression profile. Immunohistochemistry of breast cancer hormone
receptor(ER and PR), Her2, EGFR, Cytokeratin5&6 and ki-67 are the major cornerstone for
the management of breast cancer as it acts as a reproducible surrogate in predicting the
biological behaviour of the cancer.
Aims and Objective: The study aimed to describe the immunohistochemical profiles of
breast carcinoma at University of Calabar Teaching Hospital (UCTH), Calabar and attempt a
molecular classification of breast cancer using oestrogen receptor(ER), progesterone
receptor(PR) and Human epidermal growth factor receptor2(Her2).
Method: This is a retrospective descriptive study of immunohistochemistry of breast
carcinoma in UCTH. The hospital and department medical records of cases diagnosed as
breast cancer that had their samples processed in the department of Histopathology of UCTH,
Calabar and had the immunohistochemistry for ER, PR and Her2 done on them were collated
and analysed. One hundred and forty seven(147) cases with relevant histopathologic and
clinical information sampled from a four year (2011-2014) breast cancer results were studied.
The relevant demographic and pathologic results were extracted from the records and
variables like sex, age, surgery type, and histopathologic features like histologic type,
tumour size, histologic grade, and receptor status: oestrogen receptor(ER), progesterone
receptor (PR) and Human epidermal growth factor receptor 2(Her2) were analysed. The
immunohistochemistry status (ER, PR and Her2) were used to do a molecular classification
of the breast carcinoma. The molecular subtypes were described with the histopathologic
variables listed above. The findings were presented in tables and charts and statistical
10

analysis for association between the variables and hormone receptor status and Her2 and
variables with molecular subtypes were tested. The findings were compared with local and
international studies on immunohistochemical profile and molecular classes of breast
carcinoma.
Result: One hundred and forty seven (147) cases of breast cancer samples that were
processed in the department of histopathology of University of Calabar Teaching Hospital
were analysed. The result showed that majority of the cases were premenopausal age group
78.23%. The mean age at diagnosis was 46.31+/-12.75 years old. The age ranged from 21-80
years old, the modal and median ages were 40 and 45 years respectively. Ninety eight percent
(98%) were female and 2.0% male. All the males had invasive ductal carcinoma not
otherwise specified that was Luminal A. The right breast was involved in 54.42%of cases,
left was 45.58% of cases and none had bilateral breast cancer. Mastectomy was the surgical
treatment for 63.95% and lumpectomy in 36.05% of cases.
Ninety nine percent (99%) were ductal carcinoma while lobular carcinoma was 1%. Invasive
ductal carcinoma not otherwise specified (92.52%) was the commonest histologic subtype
while special types was only a minor fraction of 3.40%. The majority (75.51%) has a tumour
size of 2-5cm and moderately differentiated grade 2 was the most common accounting for
48.57%. Sixty four percent (64%) were oestrogen receptor positive. Progesterone receptor
positive was 40.14% and Her2 positive was 21.09%. Luminal A (52.38%) molecular
subtypes was the commonest followed by Triple negative (26.53%), Luminal B (12.93%) and
Her2 positive (8.16%) in that order. The Luminal molecular subtype accounted for 65.31%.
Statistical analysis showed significant differences between breast cancer hormone receptor
status and age group and histologic grade but not for tumour size and histologic type.
Statistically significant difference between molecular subtype and age was also observed.

Conclusion: Breast cancer is commoner in the premenopausal women. A majority of the breast cancer are oestrogen receptor positive but progesterone receptor and Her2 receptor negative. There is a significant relationship between breast cancer and age at presentation. Invasive ductal carcinoma not otherwise specified is the commonest histologic subtype, the special type accounted for only a small fraction. The moderately differentiated breast cancer is the commonest. Breast cancer is commonest in female while the male breast cancer is just a fraction. The most common molecular subtype is Luminal A. Triple negative subtype account for 26.3%, is the commonest in young women less than 40 years and is also associated with large-sized tumour. The majority of the cancer has size 2-5cmER ONE